NC0000272_Species Study_20201201

CANTON MILL
BALANCED AND INDIGENOUS SPECIES STUDY
FOR THE PIGEON RIVER
(CLEAN WATER ACT SECTION 316(a) DEMONSTRATION)
Prepared for:
Blue Ridge Paper Products Inc.
dba Evergreen Packaging, Canton Office
Canton, North Carolina
Prepared by:
Dr. J. Larry Wilson, Principal Investigator
University of Tennessee, Knoxville
Department of Forestry, Wildlife and Fisheries
224 Plant Sciences Building
Knoxville, TN 37996
Dr. Charles C. Coutant
120 Miramar Circle
Oak Ridge, TN 37830
Dr. John Tyner
Biosystems Engineering Department
University of Tennessee, Knoxville
Knoxville, TN 37996
January 2014

TABLE OF CONTENTS
TABLE OF CONTENTS.................................................................................................... ii
EXECUTIVESUMMARY................................................................................................
1
1. INTRODUCTION....................................................................................................
13
I.I. PURPOSE.........................................................................................................13
I.I.I. Regulatory Background..............................................................................
13
1.1.2. Need for a Variance....................................................................................
14
1.1.3. Proposed Alternative Temperature Limitation ...........................................
15
1.1.4. Study and Demonstration............................................................................
15
1.2. WHAT DOES §316(a) REQUIRE?..................................................................
16
1.2.1. Background.................................................................................................16
1.2.2. Decision Criteria.........................................................................................
18
1.2.2.1 Statute..................................................................................................
18
1.2.2.2 Federal Regulations.............................................................................
18
1.2.2.3 EPA Guidance.....................................................................................
19
1.3. MILL OPERATION.........................................................................................
22
1.3.1. Mill History.................................................................................................
27
1.3.2. Changes Since 2005 Study..........................................................................
28
1.3.3. Permit History.............................................................................................
28
1.4. PIGEON RIVER ECOSYSTEM......................................................................
29
1.4.1. Pigeon River Watershed.............................................................................
29
1.4.2. Ecoregion Classification.............................................................................
30
1.4.3. History of Degradation and Recovery........................................................
32
1.4.4. Changes in the River Since 2005 Study ......................................................
33
1.5. CHANGES IN SCIENTIFIC METHODS AND TECHNICAL KNOWLEDGE
SINCE2005 STUDY....................................................................................................
34
1.5.1. Thermal.......................................................................................................34
1.5.1.1 Thermal Plume Measurements and Model ..........................................
34
1.5.2. Biological....................................................................................................34
1.5.2.1 Reference Locations............................................................................
34
1.5.2.2 Reintroductions....................................................................................35
1.5.2.3 Larval Fish Drift..................................................................................
35
1.5.2.4 Crayfish...............................................................................................
36
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1.5.2.5 Freshwater Mussels............................................................................. 37
1.5.2.6 Fish...................................................................................................... 39
1.5.2.7 Salamanders.........................................................................................39
2. SUMMARY OF THE 2012-2013 STUDIES........................................................... 41
2.1. GENERAL DESCRIPTION............................................................................. 41
2.2. THERMAL STUDIES (Appendix A).............................................................. 41
2.2.1. Data Collections.......................................................................................... 41
2.2.2. Measured Temperatures.............................................................................. 43
2.2.3. Longitudinal Thermal Model...................................................................... 44
2.2.4. Thermal Plume Model................................................................................ 44
2.3. BIOLOGICAL STUDIES (Appendix B).......................................................... 44
2.3.1. Data Collections.......................................................................................... 44
2.3.2.
Results.........................................................................................................47
3. BALANCED INDIGENOUS POPULATIONS IN THE PIGEON RIVER
(BIOTHERMAL ASSESSMENT)...................................................................................
48
3.1. ASSESSMENT ELEMENTS...........................................................................
49
3.1.1.
Characterization of the Receiving Water Body and Community Exposure
49
3.1.2.
Biotic Categories.........................................................................................
49
3.1.3.
Representative Important Species...............................................................
51
3.1.4.
Indicators of Appreciable Harm..................................................................
52
3.1.5.
Interaction of Heat with Other Pollutants ...................................................
52
3.1.6.
Protection of the Balanced Indigenous Community ...................................
52
3.2. INDICATORS OF APPRECIABLE HARM ...................................................
53
3.2.1.
Trophic Levels (Biotic categories)..............................................................
53
3.2.2.
Diversity......................................................................................................53
3.2.3.
Sustainability (Capability to sustain itself through cyclical seasonal
changes)
....................................................................................................................
56
3.2.4.
Food -chain Species Presence......................................................................
56
3.2.5.
Lack of Domination by Pollution -tolerant Species .....................................
57
3.2.6.
Indigenous Species Increase or Decrease ...................................................
58
3.2.7.
Threatened or Endangered Species Status ..................................................
58
3.2.8.
Critical Function Zones...............................................................................
58
3.2.9.
Habitat Exclusion........................................................................................
58
3.2.10.
Thermal Effects on "Unique or Rare Habitat" ........................................
59
3.2.11.
Habitat Former Alterations......................................................................
59

3.2.12.
Nuisance Species Abundance..................................................................
59
3.2.13.
Zone of Passage.......................................................................................
60
3.2.14.
Change in Commercial or Sport Fisheries ..............................................
60
3.2.15.
Magnitude and Duration of Thermal Effects ..........................................
60
3.2.16.
Sub -lethal or Indirect Impacts.................................................................
61
3.2.17.
Interaction of Thermal Discharge with Other Pollutants ........................
61
3.2.18.
Reference Area Comparisons..................................................................
63
3.2.19.
Trends Over Time...................................................................................
67
3.3. REPRESENTATIVE IMPORTANT SPECIES (RIS).....................................
69
3.3.1.
Central Stoneroller, Camposttoma anomalum............................................
70
3.3.2.
Shiners, as a Group.....................................................................................
71
3.3.3.
Northern Hogsucker, Hypentelium nigricans.............................................
72
3.3.4.
Black Redhorse, Moxostoma duquesnei.....................................................
73
3.3.5.
Rock Bass, Ambloplites rupestris...............................................................
74
3.3.6.
Redbreast Sunfish, Lepomis auritis............................................................
75
3.3.7.
Smallmouth Bass, Micropterus dolomeiu...................................................
76
3.3.8.
Darters, as a Group, Etheostoma spp..........................................................
77
3.3.9.
River Chub, Nocomis micropogon..............................................................
80
3.3.10.
Mottled Sculpin, Cottus bairdi................................................................
80
3.3.11.
Banded Sculpin, Cottus carolinae...........................................................
81
3.3.12.
Common Cate, Cyprinus carpio.............................................................
81
3.3.13.
RIS Summary..........................................................................................
82
3.4. OTHER SPECIES OF INTEREST...................................................................
83
3.4.1.
Freshwater Mussels.....................................................................................
83
3.4.1.1.
Appalachian Elktoe, Alasmidonta raveneliana....................................
83
3.4.1.2
Wavy -rayed Lampmussel Lampsilis fasciola......................................
85
3.4.1.3
Asiatic Clam, Corbicula fluminea.......................................................
86
3.4.1.4
Other Mussel Species in the Region ....................................................
88
3.4.2.
Crayfish.......................................................................................................88
3.4.3.
Salamanders................................................................................................
90
3.4.4.
Aquatic Plant, Podostemum ceratophyllum................................................
91
3.5. COMMUNITY BALANCE..............................................................................
92
3.6. WORST CASE ASSESSMENT.......................................................................
92
4. MASTER RATIONALE.............................................................................................
94

5. REFERENCES............................................................................................................ 97
APPENDIX A. Pigeon River Temperature Study and Model: 2005-2013
APPENDIX B. A Study of the Aquatic Resources and Water Quality of the Pigeon River
(Pigeon River Biological Study: 2012-2013)
APPENDIX C. Pigeon River Fish Re -introductions in North Carolina. Progress Report
2006-2013
APPENDIX D. Analysis of Fish Kill of September 2007
APPENDIX E. Relevant Statutes and Regulations
APPENDIX F. April 2012 316(a) Study Plan (Approved)
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EXECUTIVE SUMMARY
Blue Ridge Paper Products Inc., d/b/a Evergreen Packaging ("Evergreen") is
submitting this report in accordance with Section A. 12. of National Pollutant Discharge
Elimination System Permit NC 0000272 (the "NPDES Permit", or "Permit"). The report
is being submitted more than 180 days prior to the expiration of the Permit as part of a
partial settlement agreement (the "Settlement Agreement") in Cocke County, Tennessee et
al. v. North Carolina Department of Environment and Natural Resources, Division of
Water Quality and Blue Ridge Paper Products Inc., 10 EHR 4341 and Cocke County,
Tenn., et al. v. Environmental Management Commission acting by and through its
NPDES Committee and Blue Ridge Paper Products Inc., 10 EHR 4982 (the "Contested
Cases").
The report requests continuation of alternative thermal effluent limitations
(variance from otherwise applicable limitations) contained in the NPDES Permit, as
modified by the Settlement Agreement. The extant Permit, with thermal variance, was
issued by the North Carolina Department of Environment and Natural Resources (NC
DENR) on May 26, 2010 effective July 1, 2010, based on thermal and biological studies
performed in 2005. The permit was subsequently modified by the Settlement Agreement,
effective June 1, 2012. The current and requested limitations are: a maximum monthly
average temperature rise above upstream ambient of 8.5C at Fiberville Bridge
(immediately downstream of Evergreen's Canton Mill) ("Canton Mill" or "Mill") with a
maximum weekly average of 32°C (summer) and 29°C (winter).
This report summarizes the legal, physical and biological information that
supports Evergreen's variance request as part of its 2013 NPDES permit renewal
application. Such a variance (alternative effluent limitation) is allowed under Section
316(a) of the Public Law 92-500 (Federal Water Pollution Control Act Amendments of
1972) and its reauthorizations, generally known as the "Clean Water Act" (CWA).
Approval of a thermal variance is governed by federal regulations (40 CFR 125 known as
"Subpart H") and counterpart in NC regulations (North Carolina Administrative Code
15A NCAC 2B.0208(b)).
Section 316(a) of the federal CWA permits the owner or operator of a point -
source thermal discharge to demonstrate that otherwise applicable effluent limitations on
the thermal discharge are more stringent than necessary to assure the protection and
propagation of a balanced, indigenous population (BIP) of shellfish, fish and wildlife in
and on the receiving water body. The "otherwise applicable" limitations are water -
quality based limits (water temperature standards) or national standards for best available
technology (which have not been promulgated for thermal discharges). A variance under
§316(a) of the CWA is granted under interagency guidance issued by the U.S.
Environmental Protection Agency (EPA; EPA and NRC 1977). The attributes of a
"balanced indigenous population" or community have been defined by the federal
regulations (Subpart H), EPA guidelines, and subsequent opinions by the EPA
Administrator and other regulatory bodies. As specified in the federal regulations, a
balanced indigenous community for purposes of a 316(a) demonstration is one that has
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diversity, the capacity to sustain itself through cyclical seasonal changes, contains the
necessary food chain species, and is not dominated by pollution -tolerant species.
Additional decision criteria have been added over the historical implementation of
§316(a).
The current May, 2010, NPDES permit includes a requirement that a temperature
and biological study be conducted and completed by January 2014 to allow for review of
the 316(a) alternative thermal limits (Part I A. (12.)). Evergreen and its predecessors
have performed biological studies of the Pigeon River periodically since 1987 to satisfy
permit and regulatory requirements. The most recent previous study was in 2005 (Wilson
and Coutant 2006). Evergreen contracted with the University of Tennessee, Knoxville
(UTK) to conduct studies of the Pigeon River and reference areas in 2012-2013 to
evaluate its thermal and biological conditions prior to submittal of a renewal application.
The studies included temperature measurements in the river including the thermal mixing
zone, development and validation of a longitudinal temperature model for the Pigeon
River downstream of the Mill, development of a thermal mixing -zone model, biological
surveys to confirm the existence of a balanced indigenous community under the thermal
limitations of the current variance, and the §316(a) Demonstration that includes an
integrative assessment of the thermal and biological aspects and a "Master Rationale" in
support of the current alternative effluent limitation. A final Study Plan was submitted to
NC DENR's Division of Water Quality (DWQ) on 12 April 2012 (Evergreen Packaging
2012; Appendix F), which was approved on April 24, 2012. Studies have been
coordinated with the North Carolina Department of Environment and Natural Resources
("NC DENR"), with all appropriate certifications obtained and study methods approved.
This Demonstration, supported by its detailed appendices:
• Describes the requirements of a CWA §316(a) Demonstration;
• Provides a history of operations and thermal variances at the Canton Mill;
• Summarizes the 2012-2013 thermal and biological studies of the Pigeon River
downstream of the Mill and similar reference streams in and outside the Pigeon River
watershed, with full thermal and biological reports appended;
• Provides a record of improvement in the biological community of the Pigeon River
since 1984 under a sequence of thermal variances;
• Reports a biological assessment that explicitly evaluates decision criteria in the
federal regulations (Subpart H), EPA/NRC guidance, and historical and recent opinions
by the EPA Administrator or delegate (including the Environmental Appeals Board's
2006 decision in regard to the Brayton Point Power Plant); and
• Integrates thermal and biological information in a Master Rationale in support of a
BIP in the Pigeon River in the vicinity and downstream of the Mill's thermal discharge
under the current and proposed alternative effluent limitation.
Evergreen's Canton Mill is located on the Pigeon River, a major tributary of the
French Broad River, at Canton, North Carolina. The Mill and its thermally affected reach
of river from the Mill to Waterville Reservoir are located within the "Broad Basins" sub-
region of the Level III "Blue Ridge" ecoregion, which is ecologically distinct from
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mountainous regions both upstream and downstream (Section 1.4.2). Waterville
Reservoir, with headwaters at about Pigeon River Mile ("PRM") 42 (depending on lake
elevation) and its lake -like thermal budget, effectively ends the thermal influence of the
Canton Mill. In its early years, the Mill's thermal and chemical effluents caused
significant ecological impacts to the river. Since about 1960, the Mill has worked steadily
to reduce the quantity and improve the quality of its wastewater discharges (Section
1.3.1). A Mill modernization in the early 1990s led to major improvements in the river's
biological conditions. The river habitat is largely restored from earlier impacts, as
documented in river studies for NPDES permits in 1995, 2001, and 2005. For biological
species having difficulty recolonizing the affected river reach, an interagency program of
reintroductions has been largely successful in Tennessee and North Carolina (Appendix
C).
Temperature
Understanding of the temperatures of the Pigeon River has improved through
studies in 2005 and 2012-2013 (Section 2.1 and Appendix A). Intensive data collections
in 2005 and 2012-2013 using miniature recording thermographs at numerous stations in
summer and winter have provided extensive data sets for both 3-dimensional
instantaneous modeling of the thermal plume just below the outfall and 1-dimensional
modeling of the river downstream of the outfall from 2005 to 2013. The winter and
summer thermograph data collections were utilized to calibrate the thermal longitudinal
model. Validation was completed by comparing the resulting output of the model to a
six -year record of daily temperatures collected by Mill personnel. Detailed manual
surveys of the zone of initial thermal mixing in 2012 have defined the distribution of
warmed water as it mixes with the cooler water from upstream at different river flows. A
numerical thermal plume model, CORMIX, was used to simulate the thermal plume
mixing between the Mill outfall and Fiberville Bridge. This information informs
biological decision criteria important for a 316(a) Demonstration.
The weekly average temperatures (Sunday -Saturday) for July -September for years
2005-2013 did not exceed the seasonal permit limit of 32°C (maximum was 30.3°C).
Likewise, they never exceeded the seasonal limit of 29°C from October to June
(maximum 27.3°C).
The thermal plume from the outfall mixes rapidly across the majority of the river
during low Pigeon River flow rates, with a small remaining temperature difference
(-0.5°C) from side to side at the Fiberville Bridge. During medium Pigeon River flow
rates, the thermal plume mixes into the Pigeon River more slowly, and the remaining
differential temperature is larger from side to side at Fiberville. And during high flow
rates, it appears that the far right side of the Pigeon River, opposite of the outfall, remains
at near ambient temperatures at the Fiberville Bridge. Temperatures in the zone of
discharge mixing that are high enough to block aquatic life movements would occur
rarely, only at times of very low river flow rate and warm ambient temperatures. Median
mixed river temperature increases due to Mill thermal loading (at PRM 63.3) were shown
by modeling to be 3.1, 2.5 and 1.5°C at Fiberville Bridge (PRM 63.0), above Clyde
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(PRM 59.0) and HEPCO USGS gage above the Waterville Reservoir (PRM 45.3),
respectively. With the Mill's discharge flow rate and heat flux moderately constant over
time, variations in river temperature in the immediate mixing zone and in the river to
Waterville Reservoir are largely due to seasonal ambient water temperatures and the river
flow rate, as illustrated in Appendix A.
Biology
Biological sampling studies of aquatic trophic levels were conducted in the
Pigeon River in July, August and September, 2012, following protocols of the
Environmental Sciences Section of the North Carolina Department of Environment and
Natural Resources (NC DENR ESS) to determine: (1) the current quality of these
communities near Evergreen's Canton Mill, and (2) whether thermal inputs from the Mill
disrupt or prevent balanced indigenous communities of these organisms at all trophic
levels. The sampling period was approximately two weeks longer than the sampling
effort conducted in 2005. The summer period has been chosen for periodic sampling
since the 1980s because stream temperatures are typically the warmest and there are
likely the most severe, if any, biological impacts. In 2012, water temperatures in July,
August, and September were similar to those collected at the same sites in 2005 although
there were slight variations depending on when temperatures were taken.
The study covered an approximate 60-mile reach of the Pigeon River extending
from the confluence of the forks of the Pigeon River (PRM 69.5) upstream of the Mill in
Canton, North Carolina, to PRM 10.3 near Newport, Tennessee. Nine thermally
influenced mainstem sampling stations were established within this reach from the Mill
to Waterville Reservoir. Four tributary locations and three Tennessee locations (not
influenced by the thermal discharge) were sampled as well. The thermally influenced
stations were compared to six reference stations: one each in the East and West Forks of
the Pigeon River, two locations between the confluence and the Mill (one of which was
sampled in 2005), and two sites in the nearby Swannanoa River. The sample sites were
as near as possible to the sites sampled in 2005 (Wilson 2006), except for three new sites
upstream of the Mill and the Swannanoa River sites. The original HEPCO site (PRM
42.6) was eliminated in 2012 due to limited suitable substrate and difficulty in sampling,
and replaced by a more suitable riverine site near the USGS gauging station at PRM 45.3.
In general, most of the sampling efforts were conducted within the general proximity of
previous sampling locations. The only modification was an increased area upstream of
the original PRM 64.5 site (to PRM 64.9); this portion of the river offered substantially
more substrate (riffles, runs) for fish and invertebrate collections.
Fish samples were collected by boat, backpack and pram electrofishing, and seine
hauls where suitable habitat existed. Benthic samples were collected from specific
habitat using qualitative techniques developed by the state of North Carolina and the
Tennessee Valley Authority (TVA).
Overall, the 2012 Biological Assessment found a diverse and healthy aquatic
community present in the Pigeon River below the Canton Mill. Measures of biological
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health in the river during 2012 continue to maintain or improve from the previous
biological assessments conducted in 1995, 2000, and 2005.
Fish
Fish collections from all sampling methods produced a total of 4188 fish (3485
from mainstem and upstream tributary sample locations, and 703 from mainstem
tributaries below the Mill) distributed among 56 species. There were also three hybrids
types (bluegill x green sunfish, bluegill x redbreast, green sunfish x redbreast) collected
which accounted for six of the total number count. The additional number of species
observed since 2005 is an indicator that the mainstem fish community as a whole
continues to increase its diversity and maintain stability. Fish collected throughout the
river were deemed in good health and the condition of fish downstream of the Mill was
generally comparable to that of fish upstream of the Mill.
Upstream of the Mill, the most commonly collected species were, in order of
abundance, greenfin darter (157), stoneroller (90), rock bass (56), river chub (43),
mottled sculpin (41), Tuckasegee darter (29), and redbreast sunfish (27). Downstream of
the Mill, the most commonly collected species in the mainstem, including both North
Carolina and Tennessee portions of the river, were the redbreast sunfish (537), central
stoneroller (289), smallmouth bass (242), whitetail shiner (175), and rock bass (117).
Several species were found only in the Tennessee portion of the river, including some
associated with reservoir habitats; these included the walleye, channel catfish, white
crappie, white bass, and freshwater drum.
When comparing total numbers of fish taxa collected in the North Carolina
portion of the river below the Canton Mill to Waterville Reservoir (eight sites in 2005
and nine sites in 2012, PRM 63.0 — PRM 42.6), there were 29 taxa collected in 2005 and
37 taxa in 2012. This represents a 28% increase in the number of species inhabiting the
river below the Mill. In 2005, the PRM 42.6 site had nine species of fish; that site was
not sampled in 2012 due to the influence of Waterville Reservoir. In 2012, the PRM 45.3
site replaced PRM 42.6, and there were also nine fish taxa collected there. Five of the
nine species (rock bass, redbreast sunfish, smallmouth bass, whitetail shiner, and northern
hogsucker) were common to both sites and collected in 2005 and 2012.
When examining the 2012 fish assemblage, there were eight pollution intolerant
fish species, four tolerant species, 29 intermediate species, and four species not rated by
the NC DENR (NC DENR 2001). The pollution intolerant rock bass and smallmouth
bass were collected at all mainstem stations (both upstream and downstream of the Mill),
whereas the intolerant rainbow trout occurred only at one station in the Tennessee portion
of the river. Of the tolerant species, seventeen common carp were collected in the
mainstem of the river downstream of the Mill from PRM 63.0 to PRM 10.3, and white
suckers were collected at three sites in North Carolina. Only six green sunfish were
collected, one at PRM 69.5 and five at PRM 10.3 in Tennessee.
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Redbreast sunfish was the most common tolerant species, occurring at all stations
except the most upstream site in Tennessee (PRM 24.7). When comparing the catch of
rock bass relative to redbreast sunfish collections from the North Carolina portion of the
river below the Mill, the ratio of rock bass to redbreast has improved from of 1:10.2 in
2005 to 1:5.6 in 2012; this represents a 45% improvement in numbers of the intolerant
rock bass relative to its non -indigenous competitor, redbreast sunfish.
The species richness value (11) at Fiberville (PRM 63.0), the warmest station
sampled, was somewhat less than the 16 species collected upstream of the Mill. Fish
collected at two stations immediately downstream of Fiberville, PRM 61.0 and 59.0,
produced species richness values of 14 and 17, respectively. The numbers of fish species
collected at 5 of 6 remaining downstream sample stations in the North Carolina portion of
the river were greater in 2012 than in 2005.
A principal components analysis (PCA) was conducted on a matrix of abundances
of all fish species sampled at all Pigeon River sites (including East Fork and West Fork
reference sites) and the Swannanoa River reference sites. The purpose of the PCA was to
assess how similar each of the sample sites were to each other with respect to fish
abundances (in this case total number of each species), and to assess how similar sites
were from 2005 to 2012. The PCA of the fish community indicated that there was a
gradient in fish species composition that produced three distinct groups of sites that were
similar to each other: (1) all six reference sites, including two tributaries and two
mainstem sites on the Pigeon River upstream of the Mill, and both Swannanoa River
sites, (2) all thermally influenced mainstem sites downstream from the Mill to Waterville
Reservoir, and (3) three TN sites downstream from the hydropower facility. Statistical
analyses indicated no significant differences in species diversity among the three groups.
Assessment of relative weight (Wr) values for the more abundant sport fish found
at most of the study stations indicated that: (1) the condition of rock bass, smallmouth
bass, redbreast sunfish, and bluegill from the Pigeon River is comparable to the condition
of these species from other areas in the Southeast, and (2) the condition of these species
downstream of the Canton Mill in the thermally affected portion of the river as well as
the downstream portion of the river in Tennessee were considered to be in good
condition. Mean Wr scores for rock bass (93) and redbreast sunfish (99) below the Mill
were comparable to those upstream of the Mill, and higher than mean Wr values from the
same species (rock bass, 81; redbreast, 90) from the Swannanoa River reference sites.
Overall, the results suggested no significant adverse impacts from the Mill's
thermal discharge. In summary, the 2012 fish community below the Mill has not
changed dramatically since 2005, although it has increased the species diversity and also
improved measurably in several ways: (1) the species richness from 44 species in 2005 to
51 species in 2012, an improvement of 16% since 2005, (2) darter species, which were
essentially absent downstream of the Mill in 1995, increased in number from 4 in 2005 to
5 in 2012, and were found in all nine downstream North Carolina sites, (3) the catch of
smallmouth bass increased almost ten -fold from 26 individuals in 2005 to 201 in 2012,

and (4) the ratio of rock bass relative to redbreast sunfish was 1:5.6 in 2012 and 1:10.2 in
2005, which represented a 45% increase in the less tolerant species (rock bass).
Macroinvertebrates
Macro -invertebrate sampling from throughout the study area (tributaries included)
yielded a total of 315 taxa. This number of individual taxa is up approximately 23%
from the 257 taxa collected in 2005. The numbers of the pollution -intolerant
Ephemeroptera-Plecoptera-Trichoptera complex (EPT) collected in 2012 (N=125,
including 117 genera and 8 families) increased approximately 24% from the 95 EPT taxa
collected in 2005. `EPT" is an abbreviation for Ephemeroptera + Plecoptera +
Trichoptera, insect groups that are generally intolerant of many kinds of pollution. All
three groups increased in number of taxa, with mayflies increasing by 15, stoneflies by 1,
and caddisflies by 6 taxa. The increases reflected in the 2012 collections may be in part
to an increase in the number of mainstem collection sites (14 instead of 11), and the
addition of three tributary stations (EFPR 3.5, WFPR 3.6, and Crabtree Creek). The total
number of EPT taxa collected in 2012 from the benthic community at PRM 64.5-64.9
upstream of the Mill (N=22) decreased from the numbers collected in 2005 (29) and 2000
(35). It should be noted that the decrease in taxa numbers occurred even though the
sampling area was increased somewhat to include more suitable substrate. Possible
reasons for the decrease noted include a severe drought in 2007-08, especially in North
Carolina, and a noticeable increase in agricultural operations upstream of the sites.
Turbidity levels in tributaries and at two sampling sites immediately above and below the
Mill were noticeably higher after rain events.
Even though the total number of EPT taxa collected in 2012 throughout the study
area decreased from the numbers in 2005, there was a slight increase in the number of
EPT taxa collected at the station (PRM 63.0) immediately downstream of the Mill (16
taxa in 2012, and 15 taxa in 2005). When comparing total invertebrate taxa collected in
the North Carolina portion of the river below the Mill to Waterville Reservoir (PRM 63.0
— PRM 42.6), there were 107 taxa collected in 2005 and 149 taxa in 2012, which is an
increase of 39%. The 2012 number does not include the five additional taxa found at
PRM 57.7, a new site added for the 2012 study. Taxa richness in the tributary streams
sampled in 2005 (Fines, Richland, and Jonathan's Creeks) was essentially the same in
2012 (88) as in 2005 (87) and 2000 (86).
The North Carolina Biotic Index ("NCBI"), a localized adaptation of the Index of
Biotic Integrity used nationally, scores ranged from 4.16 (Good) at PRM 64.5
immediately above the Canton Mill to 4.39 (Good) at PRM 24.7 in the Tennessee reach;
all Tennessee reach stations received the `Good' rating. The scores at NC stations
downstream from the Mill ranged from 6.70 (Fair) at PRM 63.0 to 4.69 (Good) at PRM
45.3, the farthest downstream site in that portion of the river. Four of the eight NC
stations rated a `Good -Fair' or `Good' score in 2012 compared to six of eight stations in
2005; the severe drought in 2007-08 is thought to have had a significant impact of macro -
invertebrate populations which may have influenced the NCBI scores.
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Mussels
The presence or absence of freshwater mussels at all Pigeon River mainstem
sample sites was documented. There were no mussels observed at any of the sampling
sites during 2012. These results are in line with NC DENR survey data in recent years
which have not documented any naturally -occurring mussels in the Pigeon River. High
water levels during the spring of 2013 prevented access for mussel surveys in areas other
than designated sites, and especially areas where mussel reintroductions have occurred.
Reintroductions of 10 native mussel species have been done, beginning with nine species
in TN at three sites (PRM 17.3, PRM 13.3, and PRM 8.3) in 2000-12; the other species
has been re -introduced at PRM 65.5 and PRM 55.3 in the NC portion of the river since
2010. All re -introduction sites in both North Carolina and Tennessee mainstem portions
of the Pigeon River were chosen to maximize survival and growth.
A recent research study involving UTK personnel investigated mussel survival
and growth reared in silos in Pigeon River mainstem locations both above and below the
Mill (Rooney, 2010). Results indicated that mortality rates among mussels at above -Mill
and below -Mill sites were not significantly different; however, growth rates of mussels
held in downstream silos were significantly greater than for those held at upstream sites.
Highest growth rates were observed at a site located approximately 18 km downstream
from the Mill. Several influences may have impacted growth rates, such as elevated
water temperature due to heated Mill effluent, as well as agricultural runoff with elevated
levels of nutrients. This 2010 study documented definitive proof that mussels could
survive and grow in the river below the Mill, and also provided the impetus for NC
DENR to begin their mussel reintroduction program in the NC portion of the river.
Assessment of survival at other life stages is also needed before the full extent of
potential for reintroduction of mussels to the studied reach of the Pigeon River is known.
WILDLIFE
Several wildlife species were observed along the mainstem, tributary, and
reference waterways during instream fish and invertebrate sampling events. The majority
of wildlife contact was with avian species which are usually associated with aquatic
habitat. The complete list and number of locations at which they were observed are as
follows: (1) Great blue heron — 3 sites, (2) Belted kingfisher — 2 sites, (3) Northern water
snake — 2 sites, (4) Green heron — 1 site, (5) Blue winged teal — 1 site, (6) Black -crowned
night heron, (7) Queen snake — 1 site, (8) Soft-shell turtle — 1 site, (9) Bald eagle — 1 site,
(10) Osprey — 1 site, (11) Beaver — 1 site.
Two recent research studies involving other riverine / stream wildlife included
surveys of salamanders and crayfish in the Pigeon River mainstem and tributaries. The
2009 salamander study (Maxwell, 2009) documented the presence of five of eight
salamander species (that historically existed in NC streams) in three of five study sites: in
the Pigeon River above the Mill, Jonathan's Creek, and Big Creek. No salamanders were
found in the NC mainstem portion of the Pigeon River; water quality and suitable
substrate were cited as possible contributors to the lack of salamanders there. The

crayfish study (Dunn, 2010) identified eight species in the Pigeon River system: they
were collected in the river above the Mill, in all nine Pigeon River tributaries, and in the
mainstem in the TN portion of the river. No crayfish were found in the NC mainstem
below the Mill; the study cited the drought of 2007-08 as a possible contributor to the
lack of crayfish there. The drought may have caused crayfish to seek refugia in
tributaries to escape higher levels of salinity (2X) and conductivity (lOX) in the
mainstem which were due to lower water flows which concentrated the Mill discharge
effluents.
Periphyton/Plankton
The field surveys indicated periphyton as present at all sampling stations with
little correlation of abundance with proximity to the Mill. The two lowest periphyton
concentrations were found at PRM 55.5, Hyder Mountain Bridge (NC), and PRM 24.7,
Waterville at Brown's Bridge (TN). Fiberville (PRM 63.0) below the paper Mill had
abundant periphyton.
The potamoplankton, i.e., unattached phytoplankton and zooplankton, was not
sampled because of low abundance, and their sporadic appearance was dictated by river
flows. Any sampling or collection of these groups at any given site could not be
replicated because they were transient and continuously moving downstream. There was
no indication that this biotic subcategory was present in ecologically significant amounts,
as is typical of small rivers and streams.
Macrophytes
Podostemum (hornleaf riverweed) was found in three of four reference stations
upstream of the Mill, both stations in the reference Swannanoa River, and two of three
stations in the Pigeon River in Tennessee, but not in the thermally affected reach between
the Mill and Waterville Reservoir. The species was not examined in previous 316(a)
studies, so there is no available history of change. The low dispersal ability, due to clonal
reproduction and poor seed production combined with the Pigeon River's stresses of
flooding in 2004 and drought in 2007-2008, may be limiting its ability to recolonize the
thermally affected reach after a history of pollution. Temperature does not appear to be a
limiting factor except in the reach nearest the Mill, where temperatures in summer can
exceed the reported upper limit of 30' C reported in the literature.
Overall, the 2012 Biological Assessment found a diverse and healthy aquatic
community present in the Pigeon River below the Canton Mill. Measures of biological
health in the river during 2012 continue to maintain or improve from the previous
biological assessments conducted in 1995, 2000, and 2005. Major improvements
include:
- The ratio of rock bass relative to redbreast sunfish was 1:5.6 in 2012 and 1:10.2 in
2005, which represented a 45% increase in the less tolerant species (rock bass).
Sl'

- Fish species richness increased from 44 species in 2005 to 56 species in 2012, an
improvement of 27% since 2005.
- The catch of intolerant smallmouth bass increased almost ten -fold from 26
individuals in 2005 to 201 in 2012.
- In 2005, only one intolerant fish species (rock bass) was collected in the thermally
influenced reach of the river below the Mill; in 2012, rock bass and two additional
intolerant species (smallmouth bass, greenfin darter) were found in the same
reach.
- Similarity analyses indicated there was a gradient in fish species composition that
produced three distinct groups of sites that were similar to each other. Statistical
analyses including all three biodiversity indices indicated no significant
differences in species diversity when comparing 2005 to 2012 numbers.
- Relative weight (WO values for the more abundant sport fish found at most of the
thermally affected study stations indicated body condition comparable to other
sites in the Southeast and comparable to or better than at reference sites.
- The numbers of the pollution -intolerant Ephemeroptera-Plecoptera-Trichoptera
complex collected in 2012 increased approximately 24% from the numbers taxa
collected in 2005.
- The number of macro -invertebrate taxa is up approximately 23% in the mainstem
from 257 taxa in 2005 to 315 taxa in 2012.
- Ten native mussel species have been re -introduced into the Pigeon River system.
A recent study indicated that mortality rates among above- and below- Mill sites
were not significantly different; however, growth rates of mussels held in the
downstream sites were greater than for those held at upstream sites.
Master Rationale
The Master Rationale, in accord with the EPA Guidance Manual (EPA 1977),
concludes that the thermal discharge of the Canton Mill has provided for the protection
and propagation of a balanced indigenous community of shellfish, fish and wildlife in the
Pigeon River downstream of the Mill's thermal effluent. The rationale is based on
evaluation of decision criteria in federal regulations implementing §316(a), the 1977 EPA
guidance, indicators of appreciable harm derived from historical decisions, and two
features stressed by the 2006 Brayton Point Environmental Appeals Board decision: 1)
whether the community of the thermally affected zone is what it would be without the
thermal discharge, based on comparison with reference locations, and 2) whether there is
a trend of decline or improvement in the community.
Each assessment element indicated a community that is "balanced" and similar to
what would have been there without the thermal discharge. All trophic levels of the
aquatic community (biotic categories) were present and examined in the study. Diversity
was high, although slightly less (but not statistically significant) from reference stations.
The community successfully sustains itself through cyclical seasonal changes. Abundant
food chain species are present. There is no domination by pollution tolerant species
except at the site closest to the thermal discharge in the warmest months (algae and
chironomids). Indigenous species are increasing over time relative to pollution tolerant
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ones. Aquatic organisms are successfully reproducing, as demonstrated by many young
specimens. Freshwater mussels are the only T&E listed species; the federally and state
listed Appalachian elktoe is found upstream of the Mill, but not downstream and is
planned for reintroduction following successful survival and growth of the state species
of concern, the wavy -rayed lampmussell, in the thermally affected reach. There are no
critical function zones for aquatic life in the zone of initial mixing other than a zone of
passage, which has been demonstrated to occur through detailed measurements and
plume modeling. The thermal discharge and zone of initial mixing cause minimal habitat
exclusion in the warmest months in the 0.3 PRM between the outfall and Fiberville
Bridge. There are no unique or rare habitats affected by the heated effluent. A habitat
former, the hornleaf riverweed was not found at sampling stations in the thermally
affected reach but is also sporadic in reference areas; the macroinvertebrate occupants of
its habitat are nonetheless abundant in the thermally affected reach. Trends in the aquatic
community are toward progressive improvement since studies began in 1988. Nuisance
species are not present or abundant when they occur. There are no commercial fisheries
in the Pigeon River, but the indigenous sports fish, smallmouth bass and rock bass, have
increased, especially relative to the non-native redbreast sunfish. The magnitude and
duration of any definable thermal effects (e.g., warm -water periphyton and chiromomids
in the mixing zone) are generally low and of short duration during the warmest times of
year. The high species diversity, abundance of aquatic organisms, lack of abnormalities
in fish, good relative weights of fish all indicate low sub -lethal or indirect impacts.
Detailed evaluation of other pollutants in the Pigeon River (including permitted
discharges) indicated a low likelihood that there would be detrimental interaction with the
added heat and warmer temperatures.
Reference area comparisons were favorable. Evaluation of the thermal and
biological data for nine thermally affected sites compared to six reference sites in the
Pigeon River watershed upstream of the Mill and the adjacent Swannanoa River showed
general and statistical similarity although there were some differences attributable to
historical pollution and geographic isolation that limits recolonization. Water
temperatures throughout the thermally affected reach were within the habitable zone for
aquatic life. The community in the zone of thermal mixing 0.3 PRM from the discharge
where temperatures were highest was the least similar to reference stations. Ongoing
reintroductions of fish and freshwater mussels are repopulating the thermally affected
reach with indigenous species. Other indigenous species (crayfish, salamanders) are
potential targets for additional reintroductions.
The trend of biological improvement of the thermally affected reach continued
from previous studies in 1988, 1995, 2000, and 2005. Species numbers of fish and
invertebrates have been increasing. The percentage of pollution intolerant species has
increased, such as the EPT group of macroinvertebrates and fish such as smallmouth bass
and rock bass, while relative numbers of pollution tolerant and non -indigenous species
has decreased, such as common carp and redbreast sunfish. Reintroductions of presumed
native species that have not recolonized on their own after years of absence have
generally been successful.
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The detailed studies and analyses presented in this Demonstration support
the conclusion that the existing permit limitations on the thermal discharge are
appropriate for fostering a balanced and progressively improving biological
community in the Pigeon River. Therefore, Evergreen/Blue Ridge proposes the
alternative thermal limitation as written in the 2010 Permit, following revision by
the Settlement Agreement:
The Weekly Average instream temperature measured at a point 0.4 miles
downstream of the discharge location shall not exceed 32°C during the months
of July, August, and September and shall not exceed 29°C during the months of
October through June. The monthly average instream temperature measured
at this location shall not exceed the monthly average instream temperature of
the upstream monitoring location by more than 8.5°C.
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1. INTRODUCTION
1.1. PURPOSE
Blue Ridge Paper Products Inc., doing business as (dba) Evergreen Packaging,
Canton Office ("Evergreen") is requesting the continuation of alternative thermal effluent
limitations (variance from otherwise applicable limitations) contained in its 2010
National Pollutant Discharge Elimination System (NPDES) Permit for its Canton Mill on
the Pigeon River, as modified by the Settlement Agreement (Section 1.3.3).
1.1.1. Regulatory Background
The extant Permit, with thermal variance, was issued by NC DENR on May 26,
2010, effective July 1, 2010 (NPDES No. NC0000272) based on thermal and biological
studies performed in 2005. The permit was subsequently modified by the Settlement
Agreement effective June 1, 2012. The current alternative thermal limitations are:
The Weekly Average instream temperature measured at a point 0.4 miles
downstream of the discharge location shall not exceed 32°C during the months of
July, August, and September and shall not exceed 29°C during the months of
October through June. The monthly average instream temperature measured at
this location shall not exceed the monthly average instream temperature of the
upstream monitoring location by more than 8.5°C. This value can be adjusted
based on the results of thermal modeling [See Special Condition A.(12.)
Temperature Variance Review Special Condition].
The current NPDES permit includes a requirement that a temperature and
biological study be conducted and completed by January 2014 to allow for review of the
316(a) alternative thermal limits (Part I A. (12.)). It states:
Blue Ridge Paper shall complete an analysis of temperature, including thermal
modeling and shall submit a balanced and indigenous species study, no later than
180 days prior to permit expiration date. As part of this analysis, Blue Ridge
Paper shall submit a complete temperature variance report documenting the need
for a continued temperature variance. The temperature delta of 8.5 deg C can be
adjusted based on results of the BIP [Balanced Indigenous Population] thermal
modeling.
The study shall be performed in accordance with the Division of Water Quality
approved plan. The temperature analysis and the balanced and indigenous study
plan shall conform to the specifications outlined in 40 CFR 125 Subpart H and
the EPA's Draft 316(a) Guidance Manual, dated 1977. The EPA shall be
provided an opportunity to review the plan prior to commencement of the study.
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1.1.2. Need for a Variance
A variance is needed by Evergreen for the Canton Mill because the normal
methods for regulating water temperature, state water temperature standards or Best
Available Technology for the industry are more stringent than necessary to protect and
propagate the Balanced Indigenous Community of the Pigeon River.
The Pigeon River from the Canton Water Supply Intake to the North Carolina -
Tennessee state line is designated Class C [15A NCAC 2B .0304]. It has had this
classification since 1974 (NC DWQ).
The North Carolina water temperature standard for Class C fresh waters is [15A
NCAC 02B.211(3)0)]:
(j) Temperature: not to exceed 2.8 degrees C (5.04 degrees F) above the
natural water temperature, and in no case to exceed 29 degrees C (84.2 degrees
F) for mountain and upper piedmont waters and 32 degrees C (89.6 degrees F)
for lower piedmont and coastal plain waters. The temperature for trout waters
shall not be increased by more than 0.5 degrees C (0.9 degrees F) due to the
discharge of heated liquids, but in no case to exceed 20 degrees C (68 degrees F).
Data presented in Appendix A ("temperature variance report"), demonstrate that the
general temperature standard is not met in the Pigeon River downstream of the Canton
Mill.
Further, CWA § 301 requires that thermal discharges be limited consistent with
levels achievable using the "best available technology economically achievable" (BAT)
[33U.S.C. § 131l(b)(2)(A); 33 U.S.C. § 1311(b)(2)(F)]. EPA's plans to establish closed -
cycle cooling (cooling towers) as BAT for steam -electric power industry thermal
discharges (the most common thermal effluents) were not promulgated due to lengthy
debate and litigation, so the agency sets technology -based permit limits for thermal
discharges based on Best Professional Judgment (BPJ) in a facility -specific application of
the BAT standard [33 U.S.C. § 1342(a)(1)(B) and 40 CFR § 125.3(c)(2)]. EPA has
consistently considered closed -cycle cooling as the BAT standard in its BPJ
determinations because it generally reduces heat discharge to water by —95%, with the
heat being transferred to the air instead.
Section 316(a) of the CWA allows for the selection of alternative thermal effluent
limitations (variance) based on a demonstration that a balanced indigenous population
(community) is maintained without meeting water temperature standards or BAT.
Evergreen has chosen to prepare a Demonstration, consistent with the 2010 Permit
requirements for renewing a variance, that shows that the aquatic community of the river
under the current operating Permit conditions meets the criteria for a Balanced
Indigenous Population (community) as it is defined by the statute, federal regulations,
EPA guidance, and opinions by the EPA Administrator or delegate (including a 2006
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decision by the Environmental Appeals Board regarding the Brayton Point Power Plant;
EAB 2006).
1.1.3. Proposed Alternative Temperature Limitation
The proposed alternative thermal limitation is as written in the 2010 Permit,
following revision by the Settlement Agreement (Section 1.1.1):
The Weekly Average instream temperature measured at a point 0.4 miles
downstream of the discharge location shall not exceed 32°C during the months of
July, August, and September and shall not exceed 29°C during the months of
October through June. The monthly average instream temperature measured at
this location shall not exceed the monthly average instream temperature of the
upstream monitoring location by more than 8.5°C.
1.1.4. Study and Demonstration
To comply with study provisions of the 2010 Permit, Evergreen contracted with
the University of Tennessee, Knoxville (UTK) to conduct studies of the Pigeon River and
reference areas in 2012-2013 to evaluate the river's thermal and biological conditions
prior to submittal of a renewal application. In accord with federal regulations (Subpart
H; 40 CFR 125.72(b)), a final Study Plan was submitted to NC DENR's Division of
Water Quality (DWQ) on 12 April 2012 (Evergreen Packaging 2012; Appendix F),
which was approved on April 24, 2012 (EPA reviewed the plan and provided no
comment). Studies have been coordinated with NC DENR, with all appropriate
certifications obtained and study methods approved. The studies included:
• Temperature measurements in the river including the thermal mixing zone, and in a
reference river comparable to the reach of the Pigeon River influenced by the Mill
(Appendix A);
• Development and validation of a longitudinal temperature model for the Pigeon
River downstream of the Mill (Appendix A);
• Biological surveys of periphyton, macrophytes, macroinvertebrates, and fish as well
as incidental observations of wildlife to demonstrate the existence of a balanced
indigenous community under the thermal limitations of the current permit (Appendix B);
and
• The §316(a) Demonstration report that includes an integrative assessment of the
thermal and biological aspects and a "Master Rationale" in support of the current
alternative effluent limitation based on decision criteria from the statute, federal
regulations, and historical and recent decisions by the Environmental Protection Agency
(EPA) Administrator or delegate.
This Demonstration, supported by its detailed appendices:
• Describes the requirements of a CWA §316(a) Demonstration;
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• Describes the environmental setting of the Pigeon River in relation to the Canton
Mill;
• Provides a history of operations and thermal variances at the Canton Mill;
• Summarizes the 2005 thermal and biological studies of the Pigeon River
downstream of the Mill and similar reference streams in and outside the Pigeon River
watershed, with full reports appended;
• Provides a record of improvement in the biological community of the Pigeon River
since 1984 under a sequence of thermal variances;
• Reports a biological assessment that explicitly evaluates decision criteria in the
federal regulations (Subpart H), EPA/NRC guidance, and historical and recent opinions
by the EPA Administrator or delegate (including the Environmental Appeals Board's
2006 decision in regard to the Brayton Point Power Plant); and
• Integrates thermal and biological information in a Master Rationale in support of a
BIP in the Pigeon River in the vicinity and downstream of the Mill's thermal discharge
under the current and proposed alternative effluent limitation.
1.2. WHAT DOES §316(a) REQUIRE?
This Demonstration for the Canton Mill is a Type III demonstration that is
weighed toward retrospective thermal and biological studies, under a study plan approved
by the NCDEP. It adheres to decision criteria in the statute, federal regulations, EPA
guidance, and opinions of the EPA Administrator or delegate.
1.2.1. Background
Heat (and its measure, temperature) was determined to be a "pollutant" in early
federal water -pollution control legislation and is embodied in the current Clean Water
Act (CWA) [§ 502(6). 33 U.S.C. § 1362(6)]. Heat added to water bodies can raise water
temperatures (depending on the amount of heat and the conditions in the receiving
waters), which can have effects on the physiology, behavior and reproduction of
organisms, and can cause shifts in the species make-up of the community of organisms
(NAS/NAE 1973; Majewski and Miller 1979; IAEA 1980; Langford 1990).
While thermal discharges can cause environmental changes, the cumulative
information from research and environmental assessments of thermal discharges in the
1960s and early 1970s demonstrated that waste heat discharges differed from other
pollutants in that heat is neither persistent in the environment nor does it accumulate in
aquatic food chains to become a threat to the health of fish, shellfish, wildlife, or humans,
as is the case for many toxic substances. Based on such information, the U.S. Congress
included a variance option in §316(a) of the CWA as an exception to the general rule that
permits limits be based on technology- or water quality -based standards, whichever are
more stringent [33 U.S.C. § 1326(a)].
Section 316(a) of the Clean Water Act (CWA) permits the owner or operator of a
point -source discharge to demonstrate that otherwise applicable effluent limitations on
the thermal discharge are more stringent than necessary to assure the protection and
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propagation of a balanced, indigenous population (BIP) of shellfish, fish, and wildlife in
and on the receiving water body. The term "population" in the Act is equivalent to
"community" in the ecological sense (BIC; 40 CFR 125.71(c)). Among the types of
effluent limitations for a given thermal discharge that may be determined to be
unnecessarily stringent under a Section 316(a) variance request are water quality based
effluent limitations such as discharge temperature standards, discharge zones, flow limits,
or receiving water body temperatures, as well as technology -based or industry -based
limitations. The applicable NC statute and the otherwise applicable thermal limitations
are given in Appendix E.
A variance under CWA §316(a) is granted under interagency guidance issued by
EPA (EPA 1977). This guidance provides for several types of Demonstration:
• Type I, a retrospective, non -predictive demonstration for existing facilities showing
that there has been no prior appreciable harm from the discharge;
• Type II, a predictive demonstration, using a selected group of Representative
Important Species (RIS) and Biotic Categories to show, based on thermal effects
literature (laboratory and field), that the effects of a proposed discharge are minimal; and
• Type III, a hybrid of types I and II, in which a combination of species' thermal
effects information, retrospective analyses of the aquatic community, and physical and
engineering considerations are used through a "Master Rationale" or showing of Low
Potential Impact. Type III studies require written concurrence of the EPA or other
permitting agency, generally based on an approved study plan.
In recent practice, most §316(a) Demonstrations have been Type III, in which a
variety of physical (thermal, hydraulic, engineering) and biological (e.g., RIS, community
composition, habitats, and trends in the community over time) have been used to
demonstrate a BIC. As variances have been granted and years of physical and biological
studies have been conducted at functioning thermal discharges, the Demonstrations have
tended more and more toward Type III with strong emphasis on the retrospective
characteristics of Type I. This Demonstration for the Canton Mill is a Type III
demonstration weighed toward retrospective thermal and biological studies, under a study
plan approved by the NCDEP.
Renewal applications such as this one generally include specific consideration of
any changes in conditions from the previously granted variance. Criteria commonly used
to evaluate a §316(a) Permit renewal, as opposed to a new Demonstration, are:
• Whether the nature of the thermal discharge has changed from the previous
Application;
• Whether the nature of the aquatic community has changed from the previous
Application;
• Whether the best scientific methods to assess the effects of the thermal discharge
have changed from the previous Application;
• Whether the technical knowledge of stresses caused by the thermal discharge has
changed;and
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• Whether the requirements of the current NPDES Permit have assured the
protection and propagation of a balanced indigenous population.
Nonetheless, the 2010 Permit mandates that a full thermal and "balanced and indigenous"
study be performed to serve as a basis for consideration of a renewal (Section 1.1.1).
1.2.2. Decision Criteria
Decision criteria for whether a Demonstration successfully justifies a variance are
spelled out in increasing detail in the statute, federal regulations (40 CFR 125, "Subpart
H"), EPA guidance (EPA and NRC 1977), and successive legal and administrative
opinions by the EPA Administrator or delegate. Current criteria are especially guided by
the opinion of the Environmental Appeals Board in the matter of the Brayton Point Power
Plant (EAB 2006).
1.2.2.1 Statute
The CWA authorizes alternative effluent limits on the control of the thermal
component of a discharge, so long as the limits will "assure the protection and
propagation of a balanced, indigenous population of shellfish, fish, and wildlife" (BIP) in
and on the receiving body of water. (The term "population" was used but the intent was
the ecological community, as clarified in the federal regulations, thus Balanced
Indigenous Community-BIC- is often used). The statute does not define "protection and
propagation", a BIP or the extent of a water body to be considered.
The statute clearly places the burden of proof on the applicant to demonstrate a
BIP, recognizes that there are different ways to regulate thermal discharges, requires
consideration of all components of the ecosystem, and considers the interaction of
heat/temperature with other pollutants.
1.2.2.2 Federal Regulations
The federal regulations implementing §316(a) are found in 40 CFR 125.71
through 125.73, titled "Subpart H—Criteria for Determining Alternative Effluent
Limitations Under Section 316(a) of the Act". Subpart H notably defines a BIP as
typically having four characteristics:
i. "diversity,"
ii. "the capacity to sustain itself through cyclical seasonal changes,"
iii. "presence of necessary food chain species," and
iv. "lack of domination by pollution tolerant species."
Although `indigenous" usually means native to a water body, the subpart states
that such a community "may include historically non-native species introduced in
connection with a program of management." Also, the community may include "species
whose presence or abundance results from substantial, irreversible environmental
modifications." Although debated, it is also interpreted to mean non-native species that

have extended their riverine ranges naturally through the aggregate of essentially
irreversible environmental modifications. The section notes, however, that normally,
"such a community will not include species whose presence or abundance is attributable
to the introduction of pollutants that will be eliminated" by pollution controls in other
sections of the Act or "attributable to alternative effluent limitations imposed" through
§316(a). That is, prior habitation by a pollution -tolerant community is not considered
"indigenous".
Subpart H formally introduced the notion of Representative Important Species
(RIS) as species that "are representative, in terms of their biological needs, of a balanced,
indigenous community of shellfish, fish and wildlife in the body of water into which a
discharge of heat is made." These may be the sole focus of analyses for predictive
demonstrations for new facilities, whereas they are focal species, but not the only ones,
for retrospective demonstrations.
A second section of the code (125.72) prescribes procedures that are to be
followed in applying for a §316(a) variance, including preparation of a study plan and use
of EPA guidance. The third section of the code (125.73) gives criteria and standards for
determining alternative effluent limitations, including that the alternative thermal
limitation must be protective of the BIP, all relevant information can be used, and
demonstration of absence of prior harm (or the demonstration could show that "despite
the occurrence of such previous harm, the desired alternative limitation... will
nevertheless assure the protection and propagation" of the BIP/BIC).
Subpart H is clearly the definitive regulatory document for stating what is
required of a §316(a) demonstration. Nonetheless, this federal regulation has been
expanded upon through guidance documents, litigation, and common practice.
1.2.2.3 EPA Guidance
The federal EPA has provided guidance for implementing §316(a). The most
extensive was a 1977 guidance manual that was developed in conjunction with the U.S.
Nuclear Regulatory Commission, when both agencies had some responsibility for
thermal discharges (EPA and NRC 1977). This technical guidance document was never
formally finalized, but remains a general guide for conducting §316(a) demonstrations.
A 1992 EPA review of thermal discharge regulation provided guidance largely for EPA
itself (EPA 1992). Important legal precedents have shaped EPA reviews of
demonstrations, although no specific updated guidance was issued. Nonetheless, a recent
(2006) decision by the Environmental Appeals Board in the matter of the Brayton Point
Power Plant located in EPA Region 1 (New England) has stimulated a major new
philosophy for §316(a) demonstrations (EAB 2006). This philosophy has been
implemented largely through EPA Regional reviews of new permit applications and
renewals.
EPA's 1977 guidance made important recommendations for organization and
content of a Demonstration. It recommended:
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• Organization of a Demonstration by "biotic categories" (phytoplankton,
zooplankton, habitat formers, shellfish/macroinvertebrates, fish, and other vertebrate
animals;
• A rationale for selecting RIS;
• Identification of "resource value zones," those zones near a thermal discharge
supporting "critical values", such as reproduction, growth, and migration;
• Definition of dominant species; and
• Inclusion of a "Master Rationale" that summarized all the detailed analyses of a
Demonstration into the case for protection of the BIPBIC by the proposed alternative
thermal limitations.
The guidance manual attempts to inform dischargers seeking a §316(a) variance
by providing decision criteria. Throughout the document there are suggested decision
criteria that could be explicitly addressed in a demonstration. Although useful, these
criteria have been expanded upon in subsequent years of practice, litigation, and changing
agency perspectives (see below).
Many perceived uncertainties and ambiguities in the statute, regulations, and
guidance have been contested in legal proceedings. This contesting was particularly
active in the late 1970s following the first rounds of attempts to satisfy the requirements
of § 316(a). Some decisions simply reiterated portions of the regulations and guidance,
whereas others injected more specific evaluation criteria. Two recent (2006 and 2011)
decisions are especially pertinent to current §316(a) demonstrations. Arguments by the
Environmental Appeals Board (EAB 2006) regarding denial of the alternative thermal
limitations proposed for the Brayton Point Power Plant introduced or emphasized
important considerations of reference areas and community trends. EPA Region 1's
(2011) denial of the demonstration for the Merrimack Station has served as a vehicle for
detailing EPA's current views and their legal bases (this proceeding is still underway, so
the judgment is not final).
EPA has narrowed the definition of what constitutes a balanced indigenous
community for purposes of a §316(a) demonstration after several decades of settling into
a common understanding and the issuance of many variances by state agencies (with
EPA approval). The primary emphasis has changed from demonstrating that the extant
community of mostly indigenous species has the characteristics of diversity, stability,
adequate food chains, and non -domination by pollution tolerant organisms (as prescribed
in the federal regulations' Subpart H). EPA's current interpretation, based on the
Brayton Point case, requires that the community should approximate the biotic
community that would have been there without the thermal discharge and other sources
of pollution (EAB 2006, page 557, where it is stated: that a BIP "can be the indigenous
population that existed prior to the impacts of pollutants, not solely the current population
of organisms.").
The EPA Region 4 (Southeast) objection letter for the draft Blue Ridge permit
based on the 2005 studies (February 22, 2010 letter from James B. Giattina, EPA Region
-20-

4, to Coleen H. Sullins, NC DENR) conformed to this new interpretation and stated that:
"To the question of how a permittee should identify a BIP in an area that has been
altered by impacts from an existing thermal discharge the Brayton Point E.A.D. points
out that it may be appropriate to use a nearby water body unaffected by the existing
thermal discharge as a reference area. Examination of an appropriate reference area
may be applicable in this [Blue Ridge Paper Products Canton Mill] case. "
The EPA Region 4 objection letter provided NC DENR (and thus Evergreen)
guidance for interpretation of the elements of a "balanced, indigenous community" that
are stated in Subpart H [40 CFR 125.71(c)]. The verbatim interpretations (except as
annotated in brackets) are given below (taken from the objection letter):
"A population typically characterized by diversity at all trophic levels" means
that all of the major trophic levels present in the unaffected portion of the water
body should be present in the heat affected portions. EPA recognizes that
community structure differences will occur, however, the number of species
represented in each trophic level in the unaffected portions should be reasonably
similar in the heat -affected portions of the water body. Sampling and analysis of
fish and invertebrate communities should be done such that the major trophic
levels are identified and represented by reasonably similar species distributions.
Also, the study plan should be expanded [beyond that historically done in 316(a)
studies] to include some observations of wildlife (i.e., waterfowl, mammals,
amphibians, etc.) both upstream and immediately downstream of the discharge
point that may be impacted by the thermal discharge.
2. "The capacity to sustain itself through cyclic seasonal changes" means that any
additional thermal stress will not cause significant community instability during
times of natural extremes in environmental conditions. Community data should
be collected during normal seasonal extremes as well as during optimal seasonal
conditions. Data should be compared between heat affected and unaffected
portions of the receiving water body to account for normal community changes
corresponding with a change in season.
3. "Presence of necessary food chain species" means that the necessary food webs
remain intact so that communities will be sustaining. We believe that exhaustive
food web studies are not necessary provided that invertebrate, fish and wildlife
communities are otherwise healthy, i.e., represented by sufficiently high species
diversity and abundance (appropriate for that portion of the receiving water
body) for the identified trophic levels and sustaining through normal seasonal
changes.
4. "Non -domination of pollution -tolerant species" means that in the case of a
thermal effluent, community assemblages in heat affected portions of the lake
dominated by heat tolerant species do not constitute a BIP. EPA recognizes that
because all species have varying levels of thermal tolerance, communities in the
heat affected portions of the water body may possess altered assemblages in terms
-21-

of species present and abundance. All community data should be collected,
analyzed and presented to clearly demonstrate that affected communities have not
shifted to primarily heat tolerant assemblages.
5. "Indigenous" has been further clarified in the regulations: "Such a community
may include historically non-native species introduced in connection with a
program of wildlife management and species whose presence or abundance
results from substantial, irreversible environmental modifications. Normally,
however, such a community will not include species whose presence is
attributable to the introduction of pollutants that will be eliminated by compliance
by all sources with section 301(b)(2) of the Act, and may not include species
whose presence or abundance id attributable to alternative effluent limitations
imposed pursuant to section 316(a). " [from 40 CFR 125.71(c)] EPA recognizes
that non -indigenous species are present in most aquatic systems in the United
States. All community data should be analyzed and presented to demonstrate that
community assemblages in the heat affected portions of the receiving water body
are not significantly different from non -affected communities with regard to the
number of non -indigenous species in the assemblages. [considering reference
stations]
Decision criteria resulting from key administrative and judicial precedents and
developed through experience include (in addition to those in Subpart H):
• Effects on all trophic levels;
• Effects on thermally influenced habitat, including mixing zones;
• Effects on "resource value areas" or "critical function zones";
• Indigenous species increase or decrease;
• Effects on threatened or endangered species (T&E);
• Life -cycle analysis of thermal effects on RIS, T&E, and other prominent species;
• Minimal habitat exclusion;
• Effects on unique or rare habitat;
• Alterations of habitat formers;
• Trends in the aquatic community;
• Nuisance species abundance;
• Provision of a zone of passage for migrants;
• Change in commercial or sport fisheries;
• Magnitude, frequency, duration and reversibility of any identifiable effects;
• Sublethal or indirect effects;
• Interactions with other pollutants; and
• Similarity of thermally affected area with reference areas without thermal discharge.
1.3. MILL OPERATION
Evergreen's Canton Mill is located at River Mile 63.4 on the Pigeon River at
Canton, Haywood County, North Carolina (Figure 1). The Pigeon River is a major
tributary of the French Broad River that arises in Haywood Co., North Carolina and flows
-22-

northward to its confluence with the French Broad River and Douglas Reservoir near
Newport, Tennessee (Figure 2). The Class C river drains an approximately 130 mil
watershed. The Mill withdraws water for papermaking processes from a low -head
impoundment on the Mill site and is permitted to discharge a monthly average of 29.9
million gallons per day (MGD) into the river. The discharge consists of treated industrial
waste, treated domestic waste from the Town of Canton, stormwater and landfill leachate.
River flows average 325 cfs annually at Canton and 677 cfs at HEPCO USGS gauge,
with a summer 7Q10 of 52 cfs at Canton and 120 cfs at HEPCO, a winter 7Q10 of 63 cfs
at Canton and 183 at HEPCO, and a 30Q2 of 89.9 cfs at Canton (NC DENR 2009). A
Google Earth image from Appendix A shows the Mill and the general discharge area
(PRM 63.0), including an upstream set of low -head dams to facilitate water withdrawal
by the Mill and railroad and highway bridges that serve as landmarks for monitoring of
the thermal effluent (Figure 3). The immediate mixing zone for the thermal effluent is
shown in another Google Earth image of the reach between the outfall (PRM 63.3) and
the Fiberville Bridge (PRM 63.0) (Figure 4). Additional Google Earth images in
Appendix A trace the Pigeon River from the Mill to upper Waterville Reservoir (PRM
45.1; HEPCO Gage) and in Tennessee from Waterville (PRM 25.2) to Bluffton (PRM
19.3).
-23-

Newport qg Fields (PRM 10.3)
Tennessee
Flow Direction
Buffton (PRM 19.3)
Hartford
North Carolina
■ Hydropower Facility (NC)
Ilb Stream Monitoring Location
Browns Bridge (PRM 24 1+
Cos by C reek
;gCreek
ines Creek
Hydropower Waterville
Tunnel Lake
Jonathan USGS (PRM 45.3) Upstream Clyde
Creek Ferguson Bridge (PRM
(PRM 48.2) 59.0)Thickety
Goff Course (PRM 52.3 (PRM 61.0)
Fiberville
Waynesville W1NfP bPRM fi3.0)
(PRM 54.5) Creek
Creek Canton
Jonathan Creek
Charles t. Bridge Above Mill
Hyder Mountain Bridge Clyde (PRM 57.7} `PRM fi4.5 - fi4.9}
(PRM 55.5) Below Confluence (PRM 69.5)
VV Fork Pigeon
Richland Creek River (WFPR 3.6) E Fork Pigeon
(EFPR 3.5)
W Fork Pige River
(WFPR 6.6}
Lake Logan
East Fork Pigeon
West Fork Pigeon
Figure 1. The Pigeon River from the headwaters almost to the confluence
with the French Broad River near Newport, Tennessee (upper red star), showing the
location of the Mill at Canton (lower red star; the thermal discharge is at PRM
63.3), the Waterville hydropower facility, state line between North Carolina and
Tennessee, major tributaries, and monitoring locations for biological studies.
-24-

TENNESSEE$
Jghngq City
Knoxville
GFM o *Asheville
NORTH
AROLINA
.�halE$x�aoga
FOR I A
Figure 2. Pigeon River watershed (light green) in southwestern North Carolina and
eastern Tennessee within the larger Tennessee River watershed (yellow outline).
Nearby principal cities are shown. Source: Wikipedia.
-25-

E
��. �� �
Figure 3. Google Earth image from above the Canton Mill (PRM 64.55) to the
thermal discharge (PRM 63.0). Low -head dams at left of center (white spillways)
impound water for the Mill's water intake.
low
Mill O
RR Bridge
M
Figure 4. Google Earth image of the 570-m reach between the thermal discharge
outfall (PRM 63.3) and Fiberville Bridge (PRM 63.0). The effluent plume is visible
as a discoloration. River flow 11.86 m3/s, effluent flow 1.2 m3/s.
-26-

1.3.1. Mill History
The Canton Mill was established in 1908 to produce pulp for the Champion paper
mill in Hamilton, Ohio. Throughout most of its history, the Mill was owned and operated
by Champion International Corporation. Blue Ridge Paper Products Inc. acquired
ownership of the Mill in May 1999 from Champion. In 2007, the Mill was purchased by
Evergreen Packaging, a subsidiary of the Rank Group (New Zealand). Evergreen
Packaging is headquartered in Memphis, Tennessee. The Canton Mill employs about
1200 people in Haywood County, North Carolina. An additional 300 are employed at
Evergreen's facility in Waynesville, North Carolina where paperboard is coated.
In its early years, the Mill's minimally treated discharge caused significant
ecological impacts to the river. Since about 1960, the Mill has worked to reduce the
quantity and improve the quality of its wastewater discharges. Beginning in 1990, the
Mill did a major modernization (the "Canton Modernization Project" or "CMP") at a cost
of 330 million dollars. Use of elemental chlorine was eliminated and significant changes
were made to process lines. A cooling tower was added to allow hot water from the Mill
to be reused and cooled, allowing a reduction in permitted volume of water (from 48.5
MGD to 29.9 MGD) and temperature of the thermal discharge. Oxygen delignification
and full-scale bleach filtrate recycle for pine bleach and caustic extraction stage filtrate
recycle on hardwood were initiated. These changes significantly reduced the amount and
temperature of treated wastewater released to the Pigeon River (35% reduction in heated
effluent flows, 90% reduction in stream color downstream of the Mill, 80% reduction in
BOD, and a 75% reduction in Total Suspended Solids by 2000 (EA 2001)).
The Canton Mill is now an integrated, elemental -chlorine -free (ECF) bleached
kraft pulp and paper mill with oxygen delignification and bleach filtrate recycle.
Processes at the Mill include a pine bleach line, hardwood bleach line, paperboard line
and fine paper production line. Hardwood and pine chips are transported to the site via
rail or truck and processed into pulp for paper and paperboard production. The Mill's
wastewater, along with the Town of Canton's sanitary wastewater, is treated in
Evergreen's Wastewater Treatment Plant. The treatment plant consists of a grit chamber,
bar screens, lift pumps, polymer addition, pH control (CO2 injection or H2SO4 backup),
splitter box, 3 primary clarifiers, nutrient feed, aeration basins, 3 secondary clarifiers,
residual belt presses, effluent flow measurement, cascade aeration with oxygen injection,
and oxygen injection facilities. Solids are deposited into a dedicated lined landfill. Coal
ash (from energy production) is placed into a double -lined landfill, equipped with
leachate collection. Leachate is treated in the wastewater treatment system.
The modernization project led to significant improvements in biological
conditions in the river. The river habitat is well recovered and restored from most
impacts prior to Mill modernization. By the mid-1980s, aquatic life in the river was
consistent with the expectations of a Class C stream in North Carolina (EA 1988). By the
mid 1990s, further improvements were documented based on greater faunal diversity,
improved biotic index scores, and reduced numbers of pollution -tolerant organisms (EA
-27-

1996). Further improvements were noted in the 2005 studies (Wilson and Coutant 2006)
and have been documented in the current study (Appendix B).
1.3.2. Changes Since 2005 Study
There were no significant process or operating changes affecting the thermal
discharge at the Canton Mill during the interim between the previous study (2005) and
the present one. Although some process changes were made, the result was insignificant
for parameters of the thermal discharge (Appendix A).
A significant regional drought in 2007-2008 reduced stream flows in the Pigeon
River to record lows and raised ambient river temperatures, which resulted in a one -day
kill of fish in the river immediately downstream of the discharge. Although the Mill's
discharge remained essentially constant, declining flows to below the 7Q10 at the
discharge location caused abnormally high river temperatures. A short period of lethally
high temperatures in the zone of mixing and several meters downstream was the likely
cause (Appendix D). Permit limits effective at the time were not violated, however. The
extended drought likely affected other aspects of the biological community (Appendix
B).
1.3.3. Permit History
The first NPDES permit for the Canton Mill was issued in December 1973 by the
U.S. EPA, Region 4. This permit had limits on effluent temperature but no in -stream
monitoring or temperature limits. The original NPDES permit temperature limits appear
to come from a previous 1969 state of North Carolina wastewater permit. However,
some form of a "temperature variance" for the Mill precedes the NPDES permitting
program.
North Carolina issued its first NPDES permit for the Canton Mill in 1985. It
included a §316(a) thermal variance with in -stream temperature limits of 32°C (summer),
29°C (winter) and a temperature rise above ambient (monthly average) of 13.9°C or less
at the Fiberville Bridge monitoring location 0.4 mi downstream from the discharge.
Following the 1985 permit issued by North Carolina, there were subsequent NPDES
permits issued in 1989 (by EPA), 1997 (by NC), 2001 (by NC) and 2010 (by NC).
Temperature and biological studies consistent with §316(a) guidance for a thermal
variance were initiated as requirements in the 1997 permit. The 1985 and 1989 permits
had no language requiring temperature and biological studies. Nonetheless, Champion
commissioned a biological study in 1987 that found indigenous species in the Pigeon
River both upstream and downstream of the Mill (EA 1988). Thermal and biological
studies were again conducted in 1995 following Mill modernization, which demonstrated
continual improvement (EA 1996). Temperature and biological studies were conducted
in 2000 pursuant to the 1997 permit special conditions (EA 2001) and in 2005 pursuant to
the 2001 permit. Permits through the 2001 permit retained the monthly average

maximum temperatures of 32°C (summer) and 29°C (winter) and a maximum
temperature rise above ambient of <13.9°C (monthly average).
The current permit following the 2005 studies and Demonstration (Wilson and
Coutant 2006) was issued in May 2010 with an effective date of July 1, 2010. Cocke
County, Tennessee and certain environmental groups challenged the Permit in the
Contested Cases. The Settlement Agreement reached on April 24, 2012, stipulated that
the summer and winter maximum temperatures be weekly averages rather than monthly
(NC DOJ 2012). The Settlement Agreement also stipulated certain details of the BIP
study and submittal of the study report by January 1, 2014.
1.4. PIGEON RIVER ECOSYSTEM
1.4.1. Pigeon River Watershed
The Pigeon River is a major tributary of the French Broad River that arises in the
southern Appalachian mountains of Haywood Co., North Carolina and flows northward
to its confluence with the French Broad River and Douglas Reservoir near Newport,
Tennessee (Figure 2). The river drains an approximately 130 mil watershed. The river
begins with trout -quality water in the mountains of North Carolina, originating in the
Pisgah National Forest. Land in the watershed above Canton is primarily forested with
agricultural and residential development. These developments expanded greatly between
2005 and 2012, with once fallow land converted to intensive agriculture. The river flows
steeply in a rocky channel past small towns in a largely rural landscape above Canton,
and then passes through a low -gradient and less rocky, more silty zone near Clyde, NC,
more typical of a Piedmont stream, (Table 1.1). The river then enters a high -gradient and
boulder -strewn gorge and enters Tennessee near Waterville, NC. From there, the river
gradient declines through the city of Newport, TN, to its confluence with the French
Broad River in the upper reach of Douglas Reservoir. The lower several miles of the
river are essentially reservoir backwaters. The thermally -affected reach between the Mill
and Waterville Reservoir is shown in Google Earth images in Appendix A.
Extensive information related to recent water quality in the Pigeon River and its
tributaries is included in the French Broad River Basin Water Quality Plan 2011
(http://portal.ncdenr.org/c/document library/get file?uuid=c72c7ebe-4000-4141-b777-
e5a09e5e665e&groupid=38364). Sediment is identified as a major source of stress to the
aquatic environment. Altered hydrology and naturally severe conditions such as droughts
and floods are reported to have severe impacts on aquatic life.
In 1929, the Carolina Power and Light Co. (now Duke Progress Energy)
impounded about 5 miles of the river in the gorge with Walters Dam at River Mile 38.
This formed a 340-acre (surface) Waterville Reservoir, which diverted water through a
6.2-mile-long water -conduit tunnel to a downstream powerhouse at the North Carolina -
Tennessee state line. This diversion left a 12-mile reach of river bypassed and mostly dry
of Pigeon River water at all but the highest Pigeon River flows. Local inflows maintain
the bypassed reach as a small tributary downstream of the powerhouse.
-29-

Table 1.1. Average changes in elevation (feet per mile) for defined zones of the
mainstem Pigeon River, North Carolina and Tennessee, beginning at the headwaters.
General landmarks are noted.
Zone
River Miles
Gradient
A
69-66
5.33
B
66-65 (near Canton)
5.0
C
62-60 (below Mill)
4.0
D
59-45 (near Clyde)
1.07
E
43-41.5 (Waterville Res.)
0
F 3
9-26 (gorge, bypass)
19.9
G
26-14 (below powerhouse)
6.33
H
9-7
4.5
The river, for most of its length, consists of a series of pools and runs, punctuated
by shallow riffle areas of moderate gradient. The substrate in much of the river is
dominated by cobble, gravel, and sand with interspersed larger boulders and bedrock.
Silt is more prevalent in the low -gradient reach near Clyde. A habitat survey included in
Appendix B further describes the variety of habitats that influence the aquatic species
found there.
River flow rates are volatile with modifications of riverine habitats occurring
from year to year. The highly variable flows are affected by both droughts (as in 2007-
2008) and floods caused by passing tropical storms (as in 2004). The flow rate is
typically lowest in summer with August or September having the lowest median monthly
flows at Canton (2.29 and 2.72 m3s-1, respectively in 2005-2013). The mean hourly flow
rate at the Canton USGS station from 2005-2013 was 7.4 m3s-1 with a high of 326 and a
low of 1.05 (Appendix A, Table 2). All recorded flow rates of less than 1.56 m3s-1
occurred from July through November. The river becomes noticeably turbid during times
of heavy rainfall due to runoff from agricultural lands.
Within the watershed, the reach of river that is thermally affected by the Canton
Mill extends from the discharge at Canton (River Mile 63.4) to the headwaters of
Waterville Reservoir, which is located near River Mile 42, depending on lake elevation
(see Google Earth images in Appendix A). Most of this reach is in the low -gradient zone.
Waterville Reservoir, with its lake -like thermal budget, negates any thermal influence of
the Mill on the river beyond that point.
1.4.2. Ecoregion Classification
Ecoregions denote areas of general similarity in ecosystems and in the type,
quality, and quantity of environmental resources. They were developed nationwide in a
cooperative effort between the USEPA, USDA-NCRS, and the state agencies (in this
case, NC DENR and TN DEC) to serve as a spatial framework for the research,
assessment, management and monitoring of ecosystems and ecosystem components. The
-30-

environmental features used include geology, physiography, vegetation, climate, soils,
land use, wildlife, and hydrology. Geographic areas are classified in a numbered
hierarchy of Regions and Subregions based on these environmental characteristics. The
relative importance of each characteristic varies from one ecological region to another
regardless of the hierarchical level. The ecoregions of North Carolina were compiled at a
scale of 1:250,000.
The Pigeon River watershed lies within two Level III ecoregions ("Blue Ridge"
and "Ridge and Valley") and contains six Level IV subecoregions. In North Carolina, the
Pigeon River is entirely within the Level III "Blue Ridge" ecoregion (designated 66 on
EPA ecoregions maps), which contains four Level IV subecoregions
(ftp://ftp.epa.gov/wed/ecoregions/nc/nc—eco p .pdf . The extreme headwaters (<3 mi)
lie in subecoregion "High Mountains" (66i). For approximately 15 miles downstream to
the confluence with the East Fork (PRM 69.5), the Pigeon River lies in the "Southern
Crystalline Ridges and Mountains" subregion (66d). At that point, it enters a clearly
distinct subregion, "Broad Basins" (66j), which persists for approximately 20 miles until
about the confluence with Fines Creek (PRM 42.7). There, it enters the "Southern
Metasedimentary Mountains" subecoregion (66g), which persists approximately 13 miles
to the Tennessee border (PRM 24). The Evergreen Mill in Canton and its thermally
affected reach of river to Waterville Reservoir is located within the "Broad Basins"
subregion, which is ecologically distinct from the mountainous regions both upstream
and downstream.
In Tennessee, the Pigeon River lies within two Level III ecoregions, ("Blue Ridge
Mountains" and "Ridge and Valley" (ftp://ftp.epa.gov/wed/ecore�,ions/tn/tn eco lg_pdf).
From the state border to approximately Hartford, TN, the river continues to flow through
the "Southern Metasedimentary Mountains" subecoregion (66g) of the "Blue Ridge
Mountains" ecoregion, which it left in North Carolina. It then passes through a thin
sliver of the "Southern Sedimentary Ridges" subregion (66e) through a gap in the
mountains and enters the valley portion of the "Ridge and Valley" ecoregion. The
Pigeon River valley is almost equally divided between the "Southern
Limestone/Dolomite Valleys and Low Rolling Hills" subregion and the "Southern Shale
Valleys" subregion before entering the French Broad River at the upper end of Douglas
Lake.
Particularly significant for evaluation of the thermal discharge from Evergreen's
Mill at Canton, North Carolina is the location of the Mill in the "Broad Basins"
ecoregion. This is a subregion consisting of low river gradients, agricultural lands
extending away from the river, and urban development (Canton and Clyde). It is not
surprising that the aquatic life would differ from the reaches in the mountainous
subregions of the basin. The Pigeon through the Broad Basins subregion would not be
characterized as a "mountain stream."
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1.4.3. History of Degradation and Recovery
There were no formal studies of the biology of the Pigeon River downstream of
Canton prior to the 201h century's major modifications by human activities. However,
one can presume a typical balanced aquatic community of invertebrates and small fish
that characterize undeveloped small rivers in the Appalachian Mountains today. Many
reaches likely contained smallmouth bass, rock bass, sunfish species, and a variety of
darters, shiners and other small fish species. Invertebrate fauna likely included an
assortment of larvae of mayflies, stoneflies and caddis flies as well as crayfish and
freshwater mussels. The principal impact on the aquatic system was probably from
unrestrained logging in the mountains, which would have introduced silt and increased
turbidity during rainstorms.
The lower Pigeon River in North Carolina was greatly altered in the early 201h
century. In 1906, Canton, North Carolina was chosen as a site for the pulp and paper
Mill. In early years, as much as 95% of the river flow was diverted into industrial
processes of the Mill. Most of this water was returned to the river with a heavy load of
waste and color from bleached kraft paper production. In 1929, Walters Dam was built at
River Mile 28 to form Waterville Reservoir with water diverted to an electrical
powerhouse at the Tennessee state line, thus forming a12-mile bypass reach that was
mostly left dry except during high water.
Between the Mill and the hydropower project, much of the Pigeon River was
made biologically depauperate except for pollution -tolerant microbes and some tolerant
invertebrates. Some species found refuge in larger tributaries. The color and pollution,
chemical and organic, continued through Waterville Reservoir into Tennessee and
Douglas Lake.
There was a major turn -around in the quality of water and the aquatic community
of the Pigeon River below the Canton Mill as a result of public awareness, pollution -
control activities and regulatory actions, and the Mill's modernization program beginning
in the 1980s. As described in successive study reports supporting applications for a
thermal variance for NPDES permits, the biota had improved measurably (EA 1988,
1996, 2001; Wilson and Coutant 2006). For example, the Index of Biological Integrity
(IBI; a much used index of biological diversity) had improved an average of 38% and
fish species richness had improved an average of 81 % from 1987 to 1995. Fish species
richness (a measure of diversity) at Fiberville (PRM 63.0), where river temperatures are
highest, improved from 8 species in 1987, to 12 in 1995, 19 in 2000, and 15 in 2005, but
declined to 11 in 2012 likely due to documented habitat changes (Appendix B). A wide
variety of sizes and life stages of most fish and invertebrates in the late summer
collections indicated successful reproduction. In studies conducted independently of the
company, the health of fish downstream of the Mill was shown to become comparable to
that of fish upstream of the Mill, based on the Health Assessment Index (Goede and
Barton 1990; Adams et al 1993). There was substantial improvement in the total taxa
richness of invertebrates, especially of the pollution -intolerant mayflies, stoneflies and
caddisflies while species of pollution -tolerant snails and aquatic worms declined in
-32-

density. For the most part, the aquatic community downstream of the Mill became more
similar to the community in a reference station located upstream of the Mill.
Although depauperate in the mid 20t' century, the Pigeon River downstream of
the Mill now shows the ecosystem characteristics listed in the federal regulations
(Subpart H), which defines a Balanced Indigenous Population/Community (BIP) as
typically having four characteristics: "diversity," "the capacity to sustain itself through
cyclical seasonal changes," "presence of necessary food chain species," and "lack of
domination by pollution tolerant species." As shown in the 2006 §316(a) Demonstration
and the current Demonstration, additional decision criteria for demonstrating a BIP also
have been met.
Nonetheless, certain aquatic species expected in similar rivers had not recolonized
the once -polluted reaches, which stimulated formation of an interagency working group
to foster selected reintroductions (Appendix Q. Biologists recognized that many of these
expected species were unable to re -colonize the once -polluted reaches because of
geographic isolation. The downstream Walters Dam and bypass reach blocks natural
dispersal in an upstream direction while low -head dams and small impoundments
upstream of the discharge may reduce successful downstream passage of some species.
Small, bottom -dwelling fish species such as darters, which do not disperse widely, have
been slow to move into the reach. Freshwater mussels apparently did not return
naturally, based on limited specialized sampling for them. Evergreen/Blue Ridge and
others have supported a successful reintroduction program for many of these species.
Reintroductions by the interagency group and others (e.g., Western Carolina University)
have raised the diversity, especially of pollution -intolerant species. Reintroductions have
occurred in both the Tennessee and North Carolina portions of the Pigeon River.
1.4.4. Changes in the River Since 2005 Study
Recovery from severe flooding in 2004 may have occurred. Numbers of many
biological components of the ecosystem likely have increased since the 2005 study. In
2004, the year prior to the 2005 study, the watershed experienced severe flooding from
two tropical storm systems. The floods significantly altered aquatic habitats,
macroinvertebrates and fish in the watershed as well as adjacent watersheds (NC DENR
2005). As discussed in the 2005 study report (Wilson and Coutant 2006), the 2005
sampling noted that in many cases the numbers of individuals in many species was lower
than prior to the flooding (EA 2001), although diversity remained generally high. A
general recovery in numbers would be expected since the flooding.
Severe regional drought in the summers of 2007 and 2008 may, however, have
negatively impacted the aquatic community of the Pigeon River through low flows and
elevated temperatures, which may have reduced recovery from floods. River flows were
exceptionally low during the warmest periods of these years. Maxwell (2009) noted that
according to the U.S. Geological Survey (USGS 2008), August 2007 had the lowest
recorded monthly flows since 1932 at the Pigeon River near Canton, North Carolina,
measuring station with a mean discharge rate of 61.6 cubic feet per second (cfs).
-33-

Average flow for the month of August is 198 cfs. The drought continued and June and
July of 2008 had the lowest recorded flows at the same station, with mean discharge rates
of 82.8 and 57.7 cfs, respectively. Normal flows for June and July are 260 and 193 cfs.
A brief fish kill downstream of the Mill in September 2007 was reported although live
fish were observed in the vicinity of the event a day later (see full discussion of the fish
kill and the regional drought in Appendix D).
Habitat scores for sampling sites changed somewhat since the 2005 study
(Appendix B). Scores in the thermally affected reach at the three sites closest to the Mill
decreased between 2005 and 2012 (PRM 63 from 40 to 35; PRM 61 from 79 to 63; PRM
59 from 80 to 71). There was no consistent increase or decrease at other sites. These
decreased habitat scores may explain changes in biological composition at these three
locations (section 2.3).
1.5. CHANGES IN SCIENTIFIC METHODS AND TECHNICAL
KNOWLEDGE SINCE 2005 STUDY
Some methods were changed for the 2012-2013 study from those used in the 2005
study. There were expanded thermal surveys and reference stations were added for both
thermal and biological studies. New technical knowledge about the Pigeon River has
been gained through several academic theses and studies or activities by agencies. These
are briefly described below. More detailed information from these studies and species'
information from the general literature are included in species summaries and analyses in
Section 3.
1.5.1. Thermal
1.5.1.1 Thermal Plume Measurements and Model
The 2012 study included thermal cross section measurements at the railroad
bridge below the Mill and Fiberville Bridge and associated thermal plume modeling to
obtain detailed information on the zone of thermal mixing. This was in addition to
refinements to the longitudinal temperature model for the Pigeon River, as presented in
the 2005 studies (Wilson and Coutant 2006, Appendix A). The thermal plume modeling
used the EPA -supported mixing zone model, CORMIX.
1.5.2. Biological
1.5.2.1 Reference Locations
In accord with EPA guidance related to the Brayton Point EAB decision (EAB
2006), the 2012 study methods included sampling more reference locations. In previous
studies, only one reference site was sampled (PRM 64.5). The new reference locations
included an additional station in the Pigeon River mainstem upstream of the Mill (PRM
69.5), a site each in the East Fork (EFRM 3.5) and West Fork (WFRM 3.6) and two sites
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on the lower Swannanoa River in an adjacent watershed (SRM 11.3 and SRM 1.6); see
Secton 2.2.1.
1.5.2.2 Reintroductions
There have been additional reintroductions of aquatic species in the Pigeon River
downstream of the Mill, both in North Carolina and Tennessee, by the interagency
working group. These are detailed in Appendix C, along with the history of
reintroductions with collection and release sites since the beginning of the project.
Since the 2005 study (fall 2005-fall 2013) the North Carolina portion of the
Pigeon River downstream of the Mill has received two darter species, gilt (2,179) and
banded (766); bigeye chub (481); and six shiner species, highland (1,496), mirror (8,647),
silver (2,595), telescope (3,231), Tennessee (5,766) and striped (90).
In this time, the Tennessee portion of the Pigeon River has received four darter
species, gilt (1,821), bluebreast (960), stripetail (1,613), and tangarene (69); one minnow
species, stargazing (877); two chub species, river (226) and blotched (197); mountain
madtom (2,875); two lamprey species, American brook (919) and Mountain brook (778);
and two topminnow species, northern studfish (163) and blackstripe (12).
1.5.2.3 Larval Fish Drift
A thesis on larval fish drift in the Pigeon River at Canton by Michael J. LaVoie
for the Master of Science degree from Western Carolina University was published in
2007 (LaVoie 2007). Dr. Thomas Martin, Associate Professor, Department of Biology,
supervised the work. Preliminary data from this study was reported in the 2006 BIP
study (Wilson and Coutant 2006). The thesis detailed the species and numbers of larval
fish collected by nets in April -September at three locations: 1) upstream of the Mill 100
meters below the NC 215 bridge, 2) 20 meters downstream of the low head dam but
upstream of the wastewater discharge, and 3) downstream of the discharge approximately
10 meters upstream of the second NC 215 bridge.
The composition and relative abundance of larval fish taxa differed at each of the
three sites throughout the sampling period. The sites above the Mill and downstream of
the discharge produced the majority of overall larvae (81%). Larval drift density between
the low -head dams and the discharge was less than 30% of that upstream of the Mill,
significantly lower than at the other two sites (P<0.05), which were not significantly
different. Drift densities in April and early May were highest downstream of the
discharge and dominated by catostomids (suckers). The upstream reference site produced
its greatest density in mid -May through July with cyprinids (minnows) and percids (perch
family) dominating. These two families exhibited five -fold and three -fold declines
between the reference station above the Mill and downstream of the low -head dams (but
upstream of the discharge). Drift densities peaked at the middle site in August with the
samples dominated by members of the Centrarchidae (sunfishes) and Ictaluridae
(catfishes). Knowledge of larval taxonomy was insufficient to identify specifically larvae
-35-

of two species of concern to the 316(a) study, the redbreast sunfish and rock bass,
although a taxonomist (Robert Wallus) indicated they are likely redbreast (e-mail from
Dr. Martin December 5, 2012).
The study concluded that the low -head dams with their impoundments were an
obstacle to downstream recolonization of the river below the Mill by cyprinids and
percids. These groups of generally bottom -dwelling fishes include species of concern for
repopulating the reach downstream of the Mill. Reproduction by sunfishes and catfishes
in the impoundments in summer was reflected in downstream larval drift at the
downstream two stations. The thermal discharge was not identified as a barrier to
downstream movement by fish larvae because larval densities downstream of the
discharge were generally higher than at the station immediately upstream of it.
1.5.2.4 Crayfish
A study of crayfish distribution in the Pigeon River watershed was conducted by
David Casey B. Dunn for the Master of Science degree from the University of Tennessee,
Knoxville (Dunn 2010). It was a baseline study of crayfish species in the Pigeon River
and its tributaries. It documented diversity of crayfish upstream and downstream of the
paper Mill. Crayfish were collected with multiple methods —modified minnow traps,
electroshocking, snorkeling and turning rocks --based on the characteristics of the river
reach. Crayfish were found in nine Pigeon River tributaries, in the mainstem of the river
upstream of the Mill (PRM 63.2), in the bypass reach downstream of Walters Dam, and
in Tennessee downstream of the Duke Progress Energy facility (PRM 38.0). No crayfish
were found at three stations in the river between the Mill and Waterville Lake, but
Cambarus bartonii had been found near PRM 59 and PRM 61 by Tennessee Valley
Authority biologists in 2005 (TVA 2009). They were found in all nine sampled
tributaries downstream of the Mill, suggesting that recolonizaton may be possible. Low
flows in the Pigeon River during sampling in 2007 with lowered dilution of any
chemicals from Mill effluent was suggested as a reason for lack of crayfish at stations
between the Mill and Waterville Reservoir.
Riverine crayfish species found in the overall river basin included Cambarus
bartonii, C. longirostris, C. robustus, C. sp nov (an undescribed species), Orconectes
forceps, O. virilis, O. erichsonianus, and Procambarus acutus. Two species of
burrowing crayfish were found in this study or by others, Cambarus carolinus and C.
dubius. Two species are invasives: O. virilis and P. acutus. [Note: P. acutus was found
below the Mill in the 2012 study at PRM 52.3, 55.5, and 69.51
A survey of the crayfishes of western North Carolina was published by Simmons
and Fraley (2010). This study consolidated previous collections and added many new
ones to a region -wide database. Stream species collected from the French Broad basin,
which might be expected in the Pigeon River, were the common crayfish (Cambarus
bartonii), longnose crayfish (C. longirostris), mitten crayfish (C. asperimanus), bigwater
crayfish (C. robustus), and an unnamed C. sp A (all native) and the White River crayfish
(Procambarus acutis), a non-native species. Only the White River crayfish was found in
-36-

the Pigeon River in this study, and that was below the Mill. This species is widely
distributed in eastern North America, and is typically found (also in the Pigeon River) in
pools and eddies with slow -moving water.
1.5.2.5 Freshwater Mussels
Particular attention has been given in the 2012 BIP study to freshwater mussels.
Because of generally heightened interest in mussel conservation in the Southeastern U.S,
agencies and academic institutions have devoted study time to these organisms. Surveys
for freshwater mussels generally require specialized methods, which were not employed
in the earlier BIP studies. Mussels were intensively sought in the macroinvertebrate
sampling in 2012.
Shortly after the 2005 BIP study (Wilson and Coutant 2006), biologists from the
NC DENR published an assessment of certain rare mussel populations in western North
Carolina following the floods of 2004. Two mussel species, the Appalachian elktoe
(Alasmidonta raveneliana; federally endangered) and the wavy -rayed lampmussel
(Lampsilis fasciola; a species of concern in North Carolina) were found at a station
upstream of Canton. Although no sampling was conducted in the river reach between the
Mill and Waterville Reservoir, the report indicated that, "the downstream distribution of
the Appalachian elktoe in the Pigeon River ends abruptly at Canton where habitat
becomes unsuitable due to a small impoundment and physico-chemical impacts from
point and non -point sources." The report provided useful information on the distribution
of these and other mussel species in the region.
Water quality downstream of Canton was shown to be suitable for survival and
growth of late juveniles of the wavy -rayed lampmussel, a species found upstream of
Canton. In a thesis for the Masters of Science at Western Carolina University under
direction of Dr. Thomas Martin, Caroline E. Rooney (2010) conducted an in -situ
reintroduction study with captively propagated, individually marked juveniles of two
sizes placed in enclosures in the river at two sites upstream of Canton and three
downstream sites in North Carolina and monitored for one year (Figure 5). Survival was
equivalent whereas growth was greatest at downstream sites (the downstream site nearest
Canton and immediately downstream of the paper Mill was not significantly different
from the upstream sites).
Extensive correspondence with agency and university staffs and Fraley et al.
(2010) have indicated:
• The only mussel found throughout the lower portion of the river currently is the
introduced and rapidly spreading Corbicula, which has an upstream extent as of 2012 at
Canton (e-mail from Dr. Martin, December 5, 2012) with densities similar to the Little
Tennessee River. The low -head dam likely is inhibiting further upstream expansion;
• Extensive periphyton growths complicate locating rare mussels (T.R. Russ, North
Carolina Wildlife Resources Commission, undated);
-37-

• Mussels studied by Rooney were monitored through 2012 and then released in the
river (e-mail from Dr. Martin, December 5, 2012);
• Some of Rooney's mussels were observed to be gravid, suggesting suitability of
water quality for reproduction (e-mail from S. Fraley, December 5, 2012);
• A total of 897 wavy -rayed lampmussels were introduced into the Pigeon River
below the Mill in North Carolina 2011-2013 by NC DENR (PRM 55.3, upstream of the
Richland Creek confluence and PRM 54.5). An additional 50 were released above the
Mill (PRM 65.5) in 2010 and another 369 released there in 2013 (Appendix C);
• Mussels of 12 species have been introduced into the Pigeon River in Tennessee at
PRM 8.3, 13.7 and 17.3 by University of Tennessee (UT) using mussels provided by
TWRA (Appendix Q. Monitoring is being conducted by UT.
• There was poor survival and growth of two mussel species, Cynclonaias tuberculata
and Quadrula pustulosa, transplanted from the Clinch River to the Pigeon River in
Tennessee in 2012 (Denton bridge site) and surveyed at 1, 8, and 12 months after
introduction, which was attributed to fluctuating flows and low temperatures caused by
the upstream hydropower project (Appendix Q.
5 CRABTREE
IRON -DUFF
4
CRABTREE CREEK
RICHLANDS CREEK C ` PIGEON RIVER
MW CLYDE CANTON
LAKE JUNALUSKA
0.9 0.45 0 0.9 Miles
Map Scale 1:56.182
Figure 5. Locations (circles) in the Pigeon River where the wavy -rayed lampmussel
Lampsilis fasciola was experimentally planted upstream (sites 1 and 2) and
downstream (sites 3, 4, and 5) of the thermal discharge (Rooney 2010). Survival was
equivalent at all sites whereas growth rate was greatest at two locations (4, 5)
downstream of the thermal discharge in Canton; growth at site 3 was not
statistically different from the two upstream sites.
There has been a significant increase in scientific knowledge about the
temperature requirements of freshwater mussels, by both original research and new

literature reviews involving many species. Few data are available for species found in
the Pigeon River or French Broad watershed, however. Temperature is a trigger for
many life stage events in mussels, such as spawning, release of glochidia, settlement,
metamorphosis and feeding (Dunn and Petro 2012). Thermal requirements differ among
mussel species and tend to vary depending on the environments occupied — species
occupying coldwater habitats tend to have cooler thermal requirements than those
normally occupying warmwater habitats (Dunn and Petro 2012). Thermal requirements
tend to closely match, or be slightly greater than, those of their fish hosts (Pandolfo et al.
2012). Life stages tend to have somewhat different tolerances for high temperatures,
especially early stages (Dunn and Petro 2012; Pandolfo et al. 2012). Differing tolerance
of warm water by glochidia reflect the season of release (spring, summer, or fall) (Dunn
and Petro 2012; Pandolfo et al. 2010). Adults (Dunn and Petro 2012) and juveniles
(Pandolfo et al. 2010) of most species tolerate temperatures >32°C. Warmer
temperatures (to 30°C, compared to 10 and 20°C) stimulate burrowing and the time taken
to extend the foot, but not burrowing duration (Block et al. 2013). Unpublished
observations by Jones cited in Dunn and Petro (2012) noted that newly metamorphosed
juveniles of the wavy -rayed lampmussel (found in the Pigeon River) experienced high
rates of mortality during laboratory holding at 26-27°C.
1.5.2.6 Fish
A thesis for the Masters of Science by Adrick Delray Olson (Olson 2012) at
Western Carolina University (Dr. Thomas Martin, advisor) provided new information on
the basic ecology of the mirror shiner Notorpis spectrunculus at four sites in the
Tennessee River drainage in western North Carolina. The locations were chosen for high
abundance of the species and sites were on the Pigeon River upstream of the Mill,
Hominy Creek and two sites on the Tuckasegee River. Reintroductions of this species
have not been successful downstream of the Mill. The species has very specific physical
habitat requirements — sandy eddies just downstream of obstructions. Growth rates were
highest where water temperature was the coldest. The author speculated that physical
habitat limitations could account for lack of presence and reintroduction success in the
river reach between the Mill and Waterville Reservoir
1.5.2.7 Salamanders
Salamanders in the Pigeon River were studied in snorkel surveys by Nikki J.
Maxwell in 2009 for a Masters of Science degree from the University of Tennessee
(Maxwell 2009). Eight stations were examined, four upstream and four downstream of
the Mill, as well as three stations each of four tributaries, Big Creek, Fines Creek,
Jonathan's Creek and Richland Creek. Five of the eight species of stream salamanders
historically known from Haywood County were found: Eastern hellbender
Cryptobranchus alleganiensis, Blue Ridge two -lined salamander Eurycea wilderae,
shovel -nosed salamander Desmognathus marmoratus, black -bellied salamander D.
quadramaculatus and spring salamander Gyrinophilus porphyriticus. No salamanders
were found in the main channel of the river below the Mill, although they were found in
some tributaries. Presence correlated with water quality and not habitat availability.
-39-

Drought in 2007 and 2008 was suggested as a cause for lack of salamanders downstream
of the Mill, due to concentration of the effluent and drying of egg masses.

2. SUMMARY OF THE 2012-2013 STUDIES
2.1. GENERAL DESCRIPTION
The study and analyses consisted of three main components: (1) temperature
measurement and modeling to characterize the temperature changes caused by the
thermal discharge, (2) biological sampling and analysis to demonstrate the protectiveness
of the proposed alternative limits, and (3) the "Demonstration" that integrates the thermal
and biological data with information from the scientific literature in a manner that
specifically addresses the criteria for a BIP that are itemized in 40 CFR 125.71(c),
Subpart H; EPA's guidance manual; administrative and judicial precedents; and the
February 22, 2010, letter from J. G. Giattina of EPA concerning the 2006 Demonstration.
As stipulated in EPA's guidance manual, the demonstration is summarized in a "Master
Rationale" in support of the alternative effluent limitations.
The primary region of study is the Pigeon River from immediately upstream of
Canton, North Carolina, to the upstream extent of the reservoir (Waterville Lake; PRM
42.6) formed by Walters Dam (Figure 2.3.1; see sections 2.2.1 and 2.3.1 for lists of
thermal monitoring and biological sampling sites on the Pigeon River and tributaries).
This corresponds to the "primary study area" described in the EPA Guidance Manual
(Section 4, page 78). Heat balance of the reservoir negates the influence of the Canton
Mill on temperatures there and farther downstream (thus, there is no true "far field study
area"; EPA Guidance, page 76). Nonetheless, biological sampling has included sites in
the Tennessee portion of the mainstem Pigeon River downstream of the reservoir project.
Additional sampling sites were selected as reference sites as suggested by EPA on the
basis of the Brayton appeal decision (Giattina February 22, 2010, letter). Reference sites
were locations farther upstream in the Pigeon River basin including its main tributaries,
and also on nearby Swannanoa River (Buncombe County, North Carolina), which has
comparable basin morphology and is part of the larger French Broad River basin.
2.2. THERMAL STUDIES (Appendix A)
2.2.1. Data Collections
Temperature monitors were placed in the Pigeon River and its major tributaries
upstream and downstream of the Mill's thermal discharge in periods representing
summer and winter conditions; they were placed at similar locations as in the 2005 study
(see list below). Monitors also were placed in the Swannanoa River as a reference river
comparable to the reach of the Pigeon River influenced by the Mill. The Swannanoa is in
the French Broad river basin, has similar headwater elevation and gradient characteristics
as the Pigeon River, and has a similar pattern of land use and development.
Thermal sampling locations on the Pigeon River (PRM) and the Swannanoa River
(SRM) are as follows:
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River Mile Location
PRM 64.5 Above Mill
PRM 63.3 Mill Outfall
PRM 63.2
Railroad Bridge below Outfall
PRM 63.15
Camp Creek — Tributary
PRM 63.0
Fiberville Bridge
PRM 62.9
Beaver Dam Creek — T ributary
PRM 62.5
Pump Station
PRM 61.0
DO Station — Thickety
PRM 59.0
Above Clyde
PRM 55.5
Hyder Mountain — Below Clyde
PRM 54.9
Richland Creek — Tributary
PRM 53.5
RiverView
PRM 49.8
Crabtree Creek — Tributary
PRM 46.0
Jonathan's Creek — Tributary
PRM 45.1
HEPCO Gage
PRM 42.7
Fine's Creek — Tributary
PRM 42.6
HEPCO Bridge
PRM 25.2
Waterville
PRM 22.0
Trail Hollow — Hartford
PRM19.3
Bluffton
SRM 11.3 Warren Wilson College
SRM 1.6 I-40 Exit 50
Hydrographic and meteorological data for the Pigeon River and vicinity were
obtained. The US Geological Survey's flow monitoring stations, the Canton Mill
meteorological station, and the National Weather Service's regional weather monitoring
stations were used, as appropriate.
The measured temperatures, hydrographic data, and meteorological data were
used to update a one-dimensional thermal model of the Pigeon River from upstream of
the Mill to Waterville Lake (a.k.a. Walters Lake). The thermal model developed for the
2006 316(a) demonstration was updated with temperature and river flow data from 2005-
2011, available from Blue Ridge NPDES permit monitoring in the study reach, as well as
the detailed temperature monitors deployed in 2012. The calibrated and verified model
was then used to characterize the temperature profile downstream of the Mill's discharge
at different river flows and without thermal additions by the Mill (allowing calculation of
the difference in temperature with and without the Mill, or the delta-T, at points
downstream).
The physical size and shape of the thermal plume (zone of initial mixing or
mixing zone) from the Mill's outfall was characterized between the discharge point and
the established compliance monitoring station at the Fiberville Bridge (0.4 miles
downstream from the discharge). A grid pattern was used to measure water temperatures
-42-

horizontally and vertically at representative river flows. The data were used to
parameterize a thermal plume dispersion model (EPA supported CORMIX), which was
applied at different river flows.
2.2.2. Measured Temperatures
Measured temperatures provided insights beyond being source data for model
development (below). Temperatures measured between the outfall (PRM 63.3) and
Fiberville Bridge (PRM 63.0), including stations above the railroad bridge (PRM 63.25),
at the railroad bridge (PRM 63.2) and below the railroad bridge (PRM 63.1), provided
information on the immediate mixing zone at different river flows. The measured data
showed the influence of tributaries on mainstem temperatures and the relative
temperatures of the Pigeon River and the reference Swannanoa River.
Mixing zone dynamics were strongly influenced by river flow. Much of the time
during the summer monitoring, particularly in the first 2/3rds of the period, PRM 63.25
above the railroad bridge showed approximately half of its hourly temperatures were
equal to those upstream of the outfall (i.e., ambient conditions). The other approximate
half of the temperature measurements was elevated, but not as elevated as the
temperatures at the next station, (PRM 63.2). This is consistent with a finding that the
thermal plume had crossed over to the right hand side at PRM 63.25 during
approximately half of the hourly measurements, but was not yet fully mixed causing the
right side to still show lower temperatures than downstream at all three thermographs
across the width of the river (PRM 63.2 Left, Center and Right). When comparing the
three PRM 63.2 thermographs, the Left thermograph (on the same side as the outfall) is
almost always the warmest, the Center thermograph generally has the same temperature
as the Left or slightly cooler (and during high flow events is sometimes warmer than the
Left) indicating the plume becomes more centered, and the Right thermograph is almost
always cooler indicating the thermal plume has not fully mixed by the time is reaches
PRM 63.2. During high flow events, PRM 63.2 appears to still show ambient
temperatures, meaning the thermal plume does not extend across the river at PRM 63.2
during high flow events. Measurements at PRM 63.1 and 63.0 are consistent with the
thermal plume mixing from the original left side of the river at the outfall to the right
hand side of the river further downstream. During the summer temperature
measurements, river flow rates were low, which enabled the plume to mix more readily
leaving a small amount of mixing taking place between PRM 63.1 and PRM 63. During
the winter higher flow rates, greater amounts of mixing were still occurring between
PRM 63.1 and PRM 63.
Generally, the summer temperatures of the six tributary creeks are cooler than the
ambient summer Pigeon River temperature measured at PRM 64.55, upstream of the
outfall. Tributaries generally cooled the mainstem Pigeon River downstream of the
Mill's outfall, thus lessening the presence of warmed water from the Mill.
The Swannanoa River has thermal characteristics very similar to that of the
Pigeon River upstream of the outfall. SRM 11.3 was on average 1.1 °C warmer and SRM
- 43 -

1.6 was on average 1.2°C warmer than the Pigeon River during the 4 months of collected
data during the summer of 2012 and winter of 2013.
2.2.3. Longitudinal Thermal Model
A thermal model was developed, calibrated, and validated to estimate the thermal
impact of the Evergreen Mill on the Pigeon River from Canton USGS (PRM 64.9) to
HEPCO USGS (PRM 42.6). The model was calibrated using river temperature data
collected by University of Tennessee personnel during the summer 2012 and winter of
2013. Validation of the model was completed by comparing modeled river temperatures
from 2005 - 2013 to daily river temperature measurements collected by Evergreen
personnel from the same time period. The validation phase of the modeling shows that
the model accurately predicted the Pigeon River temperature between the Canton USGS
gauging station and the HEPCO USGS gauging station. The median absolute errors
between the model -predicted river temperatures and daily measurements from 2005-
2013 are 0.6°, 0.8°, and 1.1°C for Fiberville, Above Clyde, and HEPCO USGS,
respectively.
Following validation, a series of model runs was conducted with the Mill effluent
temperature set equal to the adjacent river temperature; doing so removed the thermal
impact of the Mill from the model without affecting the flow rate of the river.
Comparisons of model runs with the Mill turned on and turned off enable a direct
comparison of the estimated thermal impact to the river. Results of this comparison show
that the median modeled increase in weekly average temperature due to Mill effluent is
3.1°, 2.5°, and 1.5°C at Fiberville, Above Clyde, and HEPCO USGS, respectively.
2.2.4. Thermal Plume Model
A numerical thermal plume mixing model, CORMIX, was run to simulate the
thermal plume mixing into the Pigeon River between the Mill outfall and the Fiberville
Bridge. These modeled results were compared to University of Tennessee measured
thermal cross sections measured at the railroad bridge just below the Mill outfall and also
at the Fiberville measured on two different days. The modeled results were also
compared to aerial photographs available on Google Earth. During low Pigeon River
flow rate, the thermal plume from the outfall mixed rapidly across the majority of the
river with a small differential temperature across the width of the river at the Fiberville
Bridge. During medium to high flow rates, the thermal plume had not mixed across the
width of the river and much larger differential temperatures across the width of the river
were present at the Fiberville Bridge.
2.3. BIOLOGICAL STUDIES (Appendix B)
2.3.1. Data Collections
Biological sampling of all aquatic trophic levels was conducted at representative
sampling stations along the length of the Pigeon River (Figure 1) and the Swannanoa

River reference stream during May -September 2012. The biotic communities of both
rivers were characterized to demonstrate "diversity, the capacity to sustain itself through
seasonal changes, presence of necessary food chain species, and ... a lack of domination
by pollution tolerant species" (Subpart H, 125.71(c)). The trophic levels included
phytoplankton, zooplankton, periphyton, macrophytes, benthic macro-
invertebrates/shellfish, fish, and wildlife (encompassing the full "shellfish, fish and
wildlife" criteria of Section 316(a) of the Clean Water Act).
During May through September 2012, UTK intensively surveyed fish and macro-
invertebrates/shellfish at 20 stations on the Pigeon River and in selected tributaries in
North Carolina (17 stations) and Tennessee (3 stations). Two (2) sites on the Swannanoa
River in North Carolina were sampled in the same manner as Pigeon River stations.
Phytoplankton, zooplankton, and wildlife were sampled less intensively to document low
abundance. River mile (PRM) refers to distance upstream of the confluence of the
Pigeon River with the French Broad River in Tennessee; SRM refers to distance
upstream of the confluence of the Swannanoa with the French Broad River in North
Carolina. New stations added to the 2005 Pigeon River sample site list are indicated by
an asterisk (*). Biological sampling locations on the Pigeon River (PRM) and the
Swannanoa River (SRM) are as follows:
River Mile
Location
WFPRM 6.6
Lake Logan*
WFPRM 3.6
West Fork Pigeon River*
EFPRM 3.5
East Fork Pigeon River*
PRM 69.5
Below confluence EFPR/WFPR*
PRM 64.5/64.9
Upstream of Mill (expanded from 2005)
PRM 63.0
Fiberville
PRM 61.0
D.O. augmentation station (Thickety)
PRM 59.0
Upstream of Clyde
PRM 57.7
Charles St Bridge/Clyde*
PRM 55.5
Downstream of Clyde
PRM Trib
Richland Creek (near Pigeon River confluence at PRM 54.9)
PRM 54.5
Downstream of Waynesville WWTP
PRM 52.3
Old Rt 209/Golf Course
PRM Trib
Crabtree Creek (near Pigeon River confluence at PRM 49.8)
PRM 48.2
Ferguson Bridge
PRM Trib
Jonathan's Creek (near Pigeon River confluence at PRM 46.0)
PRM 45.3
HEPCO Gauging Station*
PRM Trib
Fines Creek (near Pigeon River confluence at PRM 42.7)
PRM 24.7
Waterville (TN)
PRM 19.3
Groundhog Creek -Bluffton (TN)
PRM 10.3
Agriculture fields* (TN)
SRM 11.3 Warren Wilson College
SRM 1.6 I-40 Exit 50
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Sampling protocols included those used in previous 316(a) biological sampling
and standardized sampling techniques used by NC DENR and EPA. The use of multiple
protocols allows comparisons between monitoring by NC DENR and this study team.
Protocols for surveying biotic groups not sampled in the 2005 sampling (periphyton,
phytoplankton, macrophytes, zooplankton, wildlife) were developed in consultation with
NC DENR and recognized experts. Mussels/shellfish were targeted species in the
mainstem reaches due to special interest in two threatened and endangered species,
Appalachian elktoe and wavyrayed lampmussel. Periphyton sampling was conducted at
all stations using EPA rapid bioassessment methods. The distribution and abundance of
the macrophyte Podostemum (riverweed, a habitat former for macroinvertebrates) was
surveyed at each sampling station. The potamoplankton, i.e., unattached phytoplankton
and zooplankton, was not sampled because of low abundance, and their appearance was
dictated by river flows, i.e., collection of these at one site could not be verified because
they were transported downstream within minutes. Sampling was guided by the known
potential impacts of added heat and elevated temperatures in rivers of comparable size to
the Pigeon River. In accord with the EPA guidelines for small rivers, the phytoplankton,
zooplankton, and wildlife biotic categories, when sampled, were evaluated briefly as Low
Potential Impact categories. Information was obtained from NC Wildlife personnel who
work in the Pigeon River watershed, as well as Study Team observations, to document
wildlife abundance and river usage.
Attention was paid to collecting data that relate specifically to the criteria that
define a balanced, indigenous community (BIP/BIC) and to other decision criteria
specified in EPA Guidance and administrative and judicial decisions.
Despite focus on "indigenous species", the community necessarily contains
"historically non-native species introduced in connection with a program of wildlife
management and species whose presence or abundance results from substantial,
irreversible environmental modifications." (Subpart H, 125.71(c)). "Wildlife
management" has included a major program of re -introduction of species common to
similar nearby rivers (to re -populate the reach historically affected by point and non -point
sources) and stocking of non-native game species. Some historically non-native species
occur or are abundant due to basin -wide agriculture, urbanization, and upstream
impoundments. These were identified in sampling of the Pigeon River upstream of the
Mill. The community was evaluated for "species whose presence or abundance is
attributed to the introduction of pollutants that will be eliminated by compliance" with
the Clean Water Act or "species whose presence or abundance is attributable to alternate
effluent limitations imposed pursuant to section 316(a)." (Subpart H, 125.71(c)). Such
species were identified and included in the analyses.
Diversity of the aquatic community was studied to ensure that all trophic levels
present in the unaffected portion of the river were present in the heat -affected portions.
Diversity was quantified by use of several scientific diversity indices in common use in
aquatic ecology at national and international levels. Indices commonly used by NC
DENR and EPA were calculated.
AO

The capacity to sustain itself through cyclical seasonal changes was evaluated by
conducting the majority of sampling in late summer. This sampling time is currently
favored (despite 1977 EPA guidance to sample year -around) because it occurs at the end
of the extreme warmest period when community instability might be identified, and it
allows identification of year -around survival and reproduction by collecting juveniles of
most species. Sampling through the year would be redundant and constitute an
unacceptable loss of aquatic life. Additionally, because of higher river flows during
winter and spring, field data collection in these periods is more difficult and can risk field
personnel safety.
The presence of necessary food chain species was identified by sampling of
periphyton, benthic invertebrates/shellfish, and small and juvenile fish that make up
much of the riverine food web. High species diversity and abundance of known food
items are indicators of a healthy food web. EPA Guidance specifically cautions against
extremely detailed food chain analyses.
Dominance by any species especially tolerant of high temperatures was looked for
in all biological community data. NC DENR ratings of pollution tolerance and the
scientific literature were used as indicators. Factors other than increased temperature that
may cause changes in community assemblages in the Pigeon River were identified
including impoundments, land use, stream habitat, other NPDES-permitted discharges,
non -point discharges, and sites of reproduction upstream of the thermal discharge.
Although Representative Important Species (RIS) were selected in consultation
with NC DENR and EPA, most of the biological sampling and community analyses was
comprehensive and included all species amenable to sampling. Some special sampling
was undertaken to locate and evaluate certain non-RIS species of interest (mussels,
crayfish), which are not adequately represented in the normal community -wide sampling
protocols.
Similarity analyses were conducted between aquatic communities in the thermally
affected Pigeon River, reference sites upstream of the Mill and the reference stream
(Swannanoa River) to determine if the communities are significantly different (including
indigenous and non -indigenous species).
2.3.2. Results
The extensive biological results are presented in Appendix B, with summaries in this
Demonstration organized by assessment topic in Section 3. General results are also
provided in the Demonstration's Executive Summary.
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3. BALANCED INDIGENOUS POPULATIONS IN THE PIGEON RIVER
(BIOTHERMAL ASSESSMENT)
As introduced in Section 1.2, a Section 316(a) thermal variance is appropriate if it
can be demonstrated that the alternate thermal limit(s) proposed (or in this case,
continued) allows a balanced, indigenous community of aquatic organisms to be present.
If such a community is not currently present due to other limiting factors such as poor
chemical quality, then the alternative effluent limitation may nevertheless be granted so
long as the re-establishment of a balanced, indigenous community is not precluded by the
alternative thermal limits. There is no single measure by which one can say that a
community is "balanced." Rather, there is a suite of attributes shown by balanced
communities. These were presented in Section 1.2. If a community exhibits most or all
of these attributes, then one can reasonably assume "balance." Conversely, if most or all
of these attributes are missing, or if the community exhibits the major adverse impacts
identified by EPA (also presented in Section 1.2) then it is reasonable to conclude that the
community is not balanced. Furthermore, in the latter case, it still must be shown that the
lack of balance is the result of elevated temperatures, considering the interaction of
temperature with other factors.
Heat is a non -conservative substance that dissipates rapidly when heated water is
discharged to a receiving water body, as shown by the thermal studies (Appendix B).
Dissipation occurs by mixing and by heat loss to the atmosphere. Temperature, as the
measure of heat concentration, will consistently be highest at locations closest to the
discharge, which in this case is the "thermal plume" extending from the discharge to the
point of complete river mixing below Fiberville (PRM 63). Because temperatures will be
warmest in the Fiberville area, thermal impacts, should they occur, would be greatest at
this location. If there are no or few identifiable impacts at PRM 63, where absolute
temperatures and the temperature rise above the ambient upstream temperature (delta T)
are highest, then no or lower impacts would be expected at the cooler downstream
locations. However, changes or impacts at PRM 63 do not necessarily mean that they
were caused by the thermal component of the discharge. They could be caused by some
other constituent of the discharge or by poorer habitat (Appendix B).
Excessively high temperatures tend to adversely affect aquatic populations and
communities in predictable ways (e.g., low community diversity, poor sustainability
under natural seasonal fluctuations, dominance by thermally tolerant organisms, long-
term avoidance, etc., as introduced in Section 1.2). One of the tests of a Type III 316(a)
Demonstration is a showing that there is no appreciable harm (i.e., adverse impacts are
not present) or if there is appreciable harm that it is not the result of the thermal
component of the discharge considering interactions between temperature and other
factors.
The following sections demonstrate that that the Pigeon River has the prescribed
attributes of a balanced indigenous community. It also demonstrates few other indicators
of appreciable harm to species or the aquatic community. Where such indicators have
been shown in the past, the current studies show an improving trend under the present

thermal limitations and similarity with reference stations. Both similarity with reference
sites and trends over time are attributes stressed by the Environmental Appeals Board for
316(a) analyses (EAB 2006) and by EPA Region 4 in its response to Evergreen's 2006
permit application. This is notwithstanding the need to reintroduce some species below
the Mill for which geographic isolation has prevented natural re -colonization following
historically degraded conditions.
3.1. ASSESSMENT ELEMENTS
There are several standard assessment elements in a Section 316(a) evaluation
(EPA 1977). These are briefly outlined below.
3.1.1. Characterization of the Receiving Water Body and Community Exposure
The exposures of the aquatic community to altered temperatures as a result of the
Canton Mill's thermal discharge under the current permit thermal limitations are
characterized by measurements and modeling presented in Appendix A, "Pigeon River
Temperature: Measurements and Model" and summarized in Section 2.1. The habitats
and aquatic communities of the Pigeon River upstream and downstream of the Mill and
in the reference Swannanoa River are characterized in Appendix B, "A Study of the
Aquatic Resources of the Pigeon River During 2012" and summarized in Section 2.2.
3.1.2. Biotic Categories
The 316(a) Interagency Technical Guidance Manual (EPA and NRC 1977)
recommends that the community of organisms that becomes involved with the thermal
discharge be divided into several biotic categories for purposes of assessment. The EPA
also recognized that some biotic categories can be designated as "Low Potential Impact"
by virtue of the degree to which the impact is expected to be low (Appendix F, approved
Study Plan). This assessment uses the following biotic categories:
• phytoplankton
• periphyton
• macrophytes
• zooplankton and meroplankton
• shellfish/macroinvertebrates
• fish
• other vertebrate wildlife
• habitat formers
Phiplankton, drifting microscopic plants, is generally considered a biotic
category having low potential impact. The EPA guidance states:
Many water bodies, such as a majority of rivers and streams, can be
classified as `low potential impact areas' for phytoplankton, and relatively little
information is necessary for a 316(a) demonstration. " Nevertheless, more
AI

detailed information may be necessary in some instances if phytoplankton is a
substantial component of food chains supporting the balanced indigenous
population or if the thermal discharge is likely to cause a shift towards nuisance
species." (EPA and NRC 1977, Section 3.5.6.1).
The Low Potential Impact designation is by virtue of the near absence of
phytoplankton in flowing water and rapid reproductive rates of those that do occur, which
make any adverse impact fleeting (if it occurs at all). In the Pigeon River, the
phytoplankton community has generally not been considered because streams usually
have little true phytoplankton and food chains do not depend on it. Suspended algal
material is usually derived from attached algae, the periphyton community.
Phytoplankton is an important component of the aquatic community of Waterville Lake,
but thermal studies have shown there is essentially no excess temperature in the lake
attributed to the Canton Mill. Therefore, this demonstration considers phytoplankton to
be low potential impact category and will not further consider it.
Periph3jon is a biofilm of attached algae with associated microscopic animals that
covers surfaces of rocks and other submerged material. It is the predominant primary
producing assemblage in streams and rivers. Although not studied in previous years,
periphyton was a component of the 2012 studies, and is evaluated as an important part of
the aquatic community. The Rapid Assessment Protocol was used (Barbour et al. 1999).
The zooplankton/meroplankton biotic category of suspended small animals is
important in lakes, estuaries and coastal waters but not generally an important part of the
aquatic community in small rivers and streams such as the Pigeon River (EPA and NRC
1977). The guidance states that zooplankton in small rivers is generally "characterized
by low concentrations of commercially important species, rare and endangered species,
and/or those forms that are important components of the food web..." and thus
appropriately designated Low Potential Impact (EPA and NRC 1977, Section 3.3.2.2).
The exceptions are drifting freshwater mussel larvae, which are considered under the
shellfish/macroinvertebrates biotic category, and fish larvae, which are considered in the
fish biotic assemblage. Other than mussel and fish larvae, the zooplankton/meroplankton
biotic category is considered to have low potential impact and not further considered.
Shellfish and macroinvertebrates are important in the aquatic community of the
Pigeon River and are evaluated. Mussels, snails, aquatic insects, aquatic worms, and
crayfish are examples of important components of the overall aquatic communities of the
Pigeon and Swannanoa (reference) rivers. Some are evaluated as separate species
(mussels, crayfish) of interest and all as community components.
Fish are also important in the Pigeon River and are evaluated, both as community
components and as Representative Important Species (Section 3.2). Fish species that
have been slow to recolonize the Pigeon River downstream of the Mill because of
geographic isolation are being reintroduced (Appendix C) furthering the trend toward
recovery under the alternative thermal limitations in the current permit.
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Habitat formers are biotic assemblages that serve as important structure for other
members of the aquatic community. Corals in the oceans and rooted aquatic plants in
lakes and rivers would be considered habitat formers. Although previous studies of the
Pigeon River considered habitat formers to be low potential impact, the current study
included the rooted aquatic plant Podostemum at the request of the NC DENR for its
providing habitat for macroinvertebrates (Section 3.3.4). In the stream habitats of the
Pigeon River, there are no other major habitat formers and thus this biotic category is
otherwise considered to be of low potential impact and not further evaluated.
The Other Vertebrate Wildlife category is considered low potential impact.
Concerning wildlife, EPA guidance stated:
Data will be required in relatively few cases in this biotic category. In those
cases where data is required, the type of data needed is decided by the applicant.
The data selected should be the least amount of data necessary to complete this
section of the demonstration. (EPA and NRC 1977, Section 3.5.6.1.6)
The exception is salamanders (as a group), which were studied and evaluated
(Section 3.4.3). Waterfowl are normally not abundant and are not affected by thermal
changes in the river. Streamside beaver, raccoons, and other such wildlife are not likely
affected by water temperature changes. Thus, this category is not considered further.
3.1.3. Representative Important Species
The 316(a) guidance manual also recognizes that it is impractical to study in great
detail every species at a site, and that it is therefore necessary to select a smaller group of
species (the Representative Important Species, RIS) to be representative of the balanced
indigenous community (EPA and NRC 1977). Generally in 316(a) demonstrations, 5 to
15 species are chosen to represent the biotic categories that are not classified as Low
Potential Impact. The RIS are selected among species that are:
• commercially or recreationally valuable;
• threatened or endangered;
• critical to the structure and function of the ecosystem;
• potentially capable of becoming localized nuisance species; and
• necessary in the food chain for the species identified above.
The approved RIS for the 2012 study are (native unless indicated otherwise):
• Rock bass (pool -dwelling panfish important to anglers);
• Shiners (as a group; non -tolerant [intermediate to intolerant] pelagic to benthic
insectivores);
• Redbreast sunfish (pool -dwelling panfish important to anglers; non native);
• Central stoneroller (herbivore);
• Smallmouth bass (most common gamefish important for anglers);
• Northern hogsucker (thermally sensitive bottom -feeding insectivore);
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• Black redhorse (thermally sensitive bottom -feeding insectivore);
• Darters (as a group; diverse bottom -feeding insectivores);
• Common carp (thermally tolerant and potential nuisance; non native);
• River chub (pelagic omnivore);
• Mottled sculpin (bottom -dwelling insectivore); and
• Banded sculpin (bottom -dwelling insectivore).
Some selected RIS have debatable qualities for an RIS. NC DWQ suggested in
its comments on the 2001 study report that three native species be included, the river
chub, mottled sculpin, and banded sculpin (Memorandum from B. H. Tracy to J. Overton
and F. Westall, dated June 13, 2001). They were included in the 2005 study and 2006
demonstration (Wilson and Coutant 2006). The sculpins, however, have discontinuous
distributions that make their inclusion questionable (see description below). The
memorandum also suggested that the non-native common carp and redbreast sunfish
were inappropriate RIS, but we have retained them for determining trends of these non-
native species from previous studies. The carp is a potential nuisance if overly abundant
and redbreast sunfish are currently abundant and warrant detailed discussion of their
abundance trend, particularly with respect to its native competitor, rock bass.
3.1.4. Indicators of Appreciable Harm
The federal regulations, EPA guidance and subsequent EPA decisions have
identified several specific indicators or "appreciable harm" that should be avoided.
These were presented in Section 1.2 and are discussed in the assessment in Section 3.2.
3.1.5. Interaction of Heat with Other Pollutants
As required by the 316(a) guidelines, the assessment identifies and discusses any
important interactive elements between elevated temperatures from the Canton Mill's
thermal discharge and contaminants in the discharge, river water, sediments, and animal
tissues (§3.2.18). A principal concern over this interaction has been the accumulation of
dioxins in fish tissues in the Pigeon River and Waterville Reservoir, for which special
studies have been conducted for several years, with the latest in 2011. The report of the
latest special study, "Results of 2011 Dioxin Monitoring in Fish Tissue," summarizes
previous study results (Henry and Wilson 2012). It has been provided to the NC DENR
DWQ. Dioxin is briefly summarized as part of Section 3.4. Because of process changes
at the Mill noted above, dioxins are no longer produced.
3.1.6. Protection of the Balanced Indigenous Community
The ultimate test of a 316(a) Demonstration is the presence of a "balanced
indigenous community" in the receiving water for the thermal discharge. Hence, this
report is referred to as the `B&I Report" for the Balanced and Indigenous aquatic
community. The EPA guidelines specify that a "master rationale" be presented for
claims that the balanced indigenous community is protected. This rationale is presented
in the Executive Summary/Master Rationale and Section 4.
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3.2. INDICATORS OF APPRECIABLE HARM
The following indicators of appreciable harm to the aquatic community, presented
in Section 1.2 from the federal regulations, EPA guidance, and legal opinions over time,
have been evaluated based on the thermal and biological studies of the Pigeon River
conducted in 2012 and 2013 (Appendices A & B). Trends are identified from previous
316(a) studies (EA 1988, 1996, 2001; Wilson and Coutant 2006). Detailed evaluations of
the RIS are provided in Section 3.3. The data continue to support the lack of appreciable
harm to the Pigeon River from the Mill's thermal discharge even though there likely is
some localized harm in the warmest parts of the incompletely mixed thermal plume
during warmest seasons and some species are underrepresented in the river downstream
of the Mill compared to reference sites upstream and in the nearby Swannanoa River.
The order of presentation is as given in the approved Study Plan (Appendix F, pages 9-
10).
3.2.1. Trophic Levels (Biotic categories)
EPA guidance requires discussion of all biological trophic levels, referred to as
biotic categories. All relevant trophic levels of fish and invertebrates were represented in
the biological collections in the 2012 study (Appendix B) or specialized studies (theses),
and summarized in Section 3.1.2. In a river like the Pigeon, the lowest trophic level is
represented by periphyton (algae attached to surfaces) rather than the conventional
phytoplankton (suspended algae). No trophic levels were eliminated or significantly
reduced, or expanded to the point of domination by the thermal discharge (Appendix B).
Simplification of the aquatic community through loss of expected species and trophic
levels has not occurred. On the contrary, species richness continues to be higher in the
warmest parts of the river than in the cooler portions both upstream and farther
downstream. The pollution -tolerant omnivores were not abundant. The abundance of
smallmouth bass, an intolerant piscivore and top predator and valued gamefish, has
increased from low levels in the early 1990s. North Carolina has no specific trophic
classification for invertebrates, but the species list assembled from the 2012 collections
indicates a benthic community with diverse feeding habits (Appendix B).
3.2.2. Diversity
Thermally affected reaches of the Pigeon River have a diverse community of
aquatic species similar in most cases to reference sites (Appendix B).
There are many potentially useful indices of diversity of the aquatic community.
The simplest is a comparison of the number of species found in thermally affected zones
with those found in suitable reference locations. A more complex index, which includes
species numbers, biotic categories, the trophic types of species, whether indigenous or
introduced, is the Index of Biotic Integrity (IBI). The IBI produces scores that can be
compared among sampling stations and to a range from good to bad (see detailed
description in Appendix B). For the Pigeon River studies, different formulae for
calculating IBI values have been used, one developed by TVA and two by NC DENR
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(reflecting refinements between a 1995-2000 version used in 2005 and a 2006 version
used in 2012). Other indices include the Shannon Diversity Index and Evenness Index.
In 2012, the total number of fish species was higher in the thermally affected
reach between the Mill and Waterville Reservoir (average of nine sites 15.6 species,
range 11-21) than in either the two Swannanoa River reference sites (average 14.5, range
14-15) or the Pigeon River upstream of the Mill (average 14.8, range 13-16). The Pigeon
River in Tennessee was the reach with the highest number of species (average 20.0, range
10-27) reflecting the influence of lake -type species from Douglass Reservoir (French
Broad River) that can enter this lower river reach. In the thermally affected reach, the
lowest number of species (9) was found at the site farthest from the Mill having the least
temperature increase above normal (PRM 45.3, HEPCO); the next lowest (10) was at the
midpoint (PRM 57.7, Charles St. Bridge in Clyde) while the site closest to the Mill
(Fiberville Bridge) had 11. The low species numbers in the two sites closest to the Mill
in 2012 (PRM 63.0 with 11 species and 61.0 with 14) contrasts with the high species
numbers found at these sites in 2005 (15 and 24 species, respectively). The decline in
species numbers is attributed to documented changes in habitat quality of these sites since
2005.
If only indigenous fish species are considered, the pattern of fish diversity does
not change markedly (status based on TVA's listing of native and non-native species in
the Tennessee River basin, of which the Pigeon River is a part). Five non-native species
are removed from totals: rainbow and brown trout, redbreast sunfish, common carp, flat
bullhead, and yellow perch. There was little difference in average numbers of species
among the upper Pigeon River reference sites (average 13.5 species, range 12-15), the
Swannanoa River reference sites (13.5, range 13-14), and the thermally affected reach
(13.3, range 8-19). The Pigeon River in Tennessee remained with the highest number of
native species (average 18, range 9-24). In the thermally affected reach, the relative
numbers of indigenous species among sites remained similar to the total species numbers:
lowest (8) farthest from the Mill at PRM 45.3 and midway at PRM 57.7, next lowest (9)
just below the Mill (PRM 63.0).
The IBI values for 2012 did not differ greatly among stations (Appendix B).
Comparisons were made between three reference sites in the upper Pigeon River
watershed (TVA method average 41.5, range 40-44; NC DENR method average 46.8,
range 38-55), two reference sites in the Swannanoa River (TVA method average 44.0,
range 42-46; NC DENR method average 42.0, range 38-46), nine thermally affected sites
in the river downstream of the Mill to Waterville Reservoir (TVA method average 38.9,
range 26-46; NC DENR method average 37.2, range 26-48), and three sites in the Pigeon
River in Tennessee (TVA method average 44.7, range 38-48; NC DENR method average
42.0, range 38-46). All nine thermally affected sites taken together were 6.3% lower than
the upper basin reference sites (TVA method) or 20% lower (NC DENR method). The
thermally affected sites were 12% lower than the Swannanoa River reference sites (TVA
method) or I I% lower (NC DENR method). The poorest rated station using the TVA
method (26) was at the HEPCO Gauging Station (PRM 45.3; the farthest station from the
Mill in North Carolina); the poorest stations using the NC DENR method (two with 26)
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were at Fiberville (PRM 63.0, the first station downstream of the outfall) and at the
Charles Street Bridge in Clyde (PRM 57.7). The Fiberville station was 13% below the 9-
station average for the thermally affected reach between the Mill and Waterville
Reservoir (TVA method) or 30% below (NC DENR method).
The biological community improved slightly in this broad measure of "diversity"
in the river downstream of the Mill between 2005 and 2012 except for the roughly 51h-
mile reach closest to the Mill. These trends in IBI were from calculations using the TVA
method that did not change between years, as did the NC DENR method. The one
reference site upstream of the Mill sampled in 2005 declined two points from 46 to 44
(minus 4%), Fiberville declined four points from 38 to 34 (minus 11%), and Thickety
declined six points from 46 to 40 (minus 13%), but other stations rose: upstream of Clyde
from 36 to 40 (+11%), downstream of Clyde from 36 to 46 (+28%), downstream of the
Waynesville wastewater treatment plant from 38 to 40 (+5%), golf course from 40 to 46
(+15%), and Ferguson Bridge from 40 to 42 (+5%). Accounting for the 2-point decline
in the reference station, the declines in the thermally affected reach were less, and the
increases more.
Successful reintroductions of several fish species, primarily shiners and darters,
improved 2012 IBI scores for collections in the thermally affected reach in calculations
using the NC DENR method (Appendix B). Scores were raised by two points (Fiberville,
Charles St. Bridge in Clyde, Golf Course), five points (below Waynesville wastewater
treatment plant), and 10 points (Downstream of Clyde, Ferguson Bridge).
Reintroductions are of species that have limited capability for self -colonization due to
their low dispersal rates and presence of physical barriers (upstream and downstream
mainstem dams). Their survival and reproduction supports the hypothesis of restricted
natural dispersion and the suitability of the river for protection and propagation of these
species.
Several fish diversity indices showed that the average of all thermally affected
sites was only slightly less diverse than the reference sites, but that highest diversity
occurred where thermally influenced (Appendix B). Thermally affected averages were
generally brought down by the site closest to the Mill (Fiberville). Principal component
analyses (cannonical analyses) indicated lack of significant differences in species
diversity among three groupings. The three groupings showed up in both years: reference
stations (although they are scattered), thermally affected stations (more tightly
grouped/similar) and Tennessee stations. Three thermally affected stations in 2012 (PRM
63, 61, and 57) are farther removed from the reference stations and other thermally
affected stations than they were in 2005 (less similar), likely due to the drought and
higher temperatures seen during the period regionally. But, the single 2005 control
station (PRM 64.05) also dropped on the vertical axis between 2005 and 2012, suggesting
that the declines in PRM 63, 61, and 57 seen in 2012 were perhaps partially the result of
regional changes, not just the thermal discharge. Finally, the variability in similarity
among the nine thermally affected stations in 2012 on these axes is similar to (even a bit
less than) the variability among the six reference stations. (Also see section 3.2.18).
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3.2.3. Sustainability (Capability to sustain itself through cyclical seasonal changes)
The Pigeon River downstream of the Mill is demonstrably resilient to
environmental stressors and is self -sustainable (Appendix B). A healthy biological
community can be considered self-sustaining when there is evidence of good numbers of
young of the year and juveniles in summer collections from year to year. The NC Index
of Biological Integrity (NCIBI) is an indicator of good reproduction of RIS and non-RIS
species by including the percentage of species represented by multiple size (age) classes.
North Carolina sites downstream of the Mill have consistently scored a 5 at some stations
(the best possible score) during the previous studies (EA 1996, 2001; Wilson and Coutant
2006). In 2012, multiple age -class scores were higher in reference stations (average 4.3,
range 3-5) than the thermally affected reach (average 3.1, range 1-5). Nonetheless,
significant reproduction is taking place in the thermally affected reach. The progressive
repopulation of the river after years of pollution is a strong indicator of sustainability of
the regional biota.
This recovery has been in spite of naturally severe environmental stressors. There
were four years of drought from 1997 to 2002 at a time when the biotic community was
showing considerable improvement (EA 2001). The disastrous floods of 2004 with
washout of organisms, scour and reordering of substrate habitats was a major ecosystem
stress that would have tested sustainability. NCIBI scores in 2005 were, indeed, lower at
some stations due to reduced numbers but not species diversity (Wilson and Coutant
2006). Sustainability of the aquatic community was again tested by drought in 2007-
2008. In the 2012 study following that drought, the IBI evidence indicates that while the
most heated stations (Fiberville and Thickety) showed some decline in IBI scores
between 2005 and 2012, other stations showed significant increase in scores (§3.2.2;
Appendix B).
3.2.4. Food -chain Species Presence
An abundance of allochthanous detritus, periphyton, aquatic insects, and small
fish indicates that the food chain is complete (Appendix B). The species assemblage
represents typical feeding guilds indicating a favorable food chain. For a biotic
community to be considered "balanced" most of the individuals making up that
community must exhibit good nutrition. This has been assessed by examining their
relative robustness (Relative Weight Wr) or by looking for evidence of nutritional
abnormalities. In 2005, Wr values indicated that: (1) the condition of rock bass,
smallmouth bass, redbreast sunfish, green sunfish, and bluegill from the Pigeon River
was comparable to the condition of these species from other areas of the Southeast, and
(2) the condition of these species downstream of the Canton Mill was generally
comparable to or better than in specimens collected upstream of the Mill (Wilson and
Coutant 2006). In 2012, assessment of relative weight (Wr) values for the more abundant
sport fish found at most of the study stations indicated that: (1) the condition of rock bass,
smallmouth bass, redbreast sunfish, and bluegill from the Pigeon River is comparable to
the condition of these species from other areas in the Southeast, and (2) the condition of
these species downstream of the Canton Mill in the thermally affected portion of the river
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as well as the downstream portion of the river in Tennessee were considered to be in
good condition. Mean Wr scores for rock bass (93) and redbreast sunfish (99) below the
Mill were comparable to those upstream of the Mill, and higher than mean Wr values
from the same species (rock bass, 81; redbreast, 90) from the Swannanoa River reference
sites.
3.2.5. Lack of Domination by Pollution -tolerant Species
The aquatic community downstream of the Mill's thermal discharge is not
dominated by pollution -tolerant species. In 2005, only four of the 45 fish species
sampled were rated as tolerant by the NC DENR (NC DENR 2001). With the exception
of redbreast sunfish, thermally tolerant species were rare (e.g., goldfish), uncommon
(e.g., largemouth bass, channel catfish), or moderately common (e.g., common carp).
The pattern in 2012 was similar.
There is a trend toward relative decrease of pollution -tolerant species. The
tolerant redbreast sunfish is common to abundant in both the thermally affected reach and
reference stations, but generally does not dominate the fish community diversity below
the Mill. Its abundance in the thermally affected reach relative to its native competitor,
rock bass, is declining over time (§3.3.6). Tolerant green sunfish have declined to
complete absence; they were found at all but two mainstem sites in 2000, and only at
PRM 61.0 in 2005; there were no green sunfish collected in the NC portion of the river
below the Mill in 2012. The intolerant smallmouth bass (§3.3.7) and rock bass (§3.3.5)
were collected at all stations downstream of the Mill, even the warmest, in both 2005 and
2012. Intolerant darter species (§3.3.8) occurred at all stations sampled, with highest
diversity in the thermally affected reach between the Mill and Waterville Reservoir.
Snails, aquatic worms and some midges, the macroinvertebrates most likely to be
thermally tolerant, have decreased in relative abundance over the periods of biological
studies. Of these three taxa, none was dominant downstream of the Mill during 2012.
The pond snail Physa was widely distributed in low numbers. Aquatic worms were
collected in small numbers with scattered distribution. Certain Chironomids (midges)
were most abundant at the station closest to the Mill (PRM 63.0), but were similarly
abundant at the lowest station in Tennessee not affected by the thermal discharge.
The fish community in the North Carolina reach downstream of the Mill has more
characteristics of a warm -water fish community than does the river upstream of the Mill.
Much of this attribute may be related to the physical nature of the river between the Mill
and Waterville Reservoir. It is a lower gradient stream in the "Broad Basins" ecoregion
(§ 1.4.2), with more pool habitat than upstream ("High Mountains" and "Southern
Crystalline Ridges and Mountains" subregions). Stations upstream of the Mill had more
canopy cover (trees, shrubs) than the reaches downstream of the Mill. The fish
community downstream of the Mill is similar to the reference river stations on the
Swannanoa River, located in similar environments.
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The periphyton community in a small area of the zone of initial mixing is
dominated by blue-green algae with associated thermally tolerant chironomid larvae.
This is of low magnitude and duration, as it occurs in a small area and would be restricted
to a few weeks in summer based on seasonal temperatures (§3.2.16).
3.2.6. Indigenous Species Increase or Decrease
Indigenous fish species showed community patterns similar to those for all fish
species. As noted above (§3.2.2), the species richness of indigenous fish species was
similar to all fish species. There was little difference in average numbers of indigenous
species among the upper Pigeon River reference sites (average 13.5 species, range 12-
15), the Swannanoa River reference sites (13.5, range 13-14), and the thermally affected
reach (13.3, range 8-19).
3.2.7. Threatened or Endangered Species Status
The status of threatened or endangered species in the Pigeon River downstream of
the Mill's thermal discharge has recently improved. The two listed species in the river
basin are the Appalachian elktoe Alasmidonta raveneliana (federal and state endangered;
§3.4.1.1) and the wavy -rayed lampmussel Lampsilis fasciola (state species of concern;
§3.4.1.2). Neither was found in the Pigeon River downstream of the Mill in previous
studies and it was assumed at that time that there were no T&E species to be evaluated.
They were reported subsequent to the 2005 study, however, to occur in the river upstream
(Fraley and Simmons 2006). Inability to recolonize from upstream due to small
impoundments and residual pollution were presumed by Fraley and Simmons to be the
reasons for lack of the species downstream of the Mill. Subsequently, a study
demonstrated that the wavy -rayed lampmussel could survive in the thermally affected
zone (Rooney 2010; §1.5.2.5) and become gravid (§3.4.1.2). As a result, the species has
been reintroduced below the Mill in 2011-2013. Follow-up collections are planned to
evaluate survival, growth and reproduction, which will occur over several years.
Encouraging results with this species has led to tentative plans to reintroduce the
Appalachian elktoe, as well.
3.2.8. Critical Function Zones
There are no critical function zones in the vicinity of the Canton Mill's thermal
discharge and zone of initial mixing aside from providing a zone of passage (§3.2.1.4).
There are no special spawning grounds or nursery areas, and the habitat is similar to the
remainder of the river.
3.2.9. Habitat Exclusion
There is minimal habitat exclusion due to the thermal discharge and zone of initial
mixing. The immediate zone of mixing along the west side of the river, primarily
between the discharge (PRM 63.4) and Fiberville Bridge (PRM 63.0) (Appendix A,
figures 75-79) may exclude some thermally sensitive fish and invertebrates in the

warmest times of summer (temperatures >32°C). At times of sampling in late summer,
however, the Fiberville Bridge station typically has had the highest species diversity of
any station in the river.
3.2.10. Thermal Effects on "Unique or Rare Habitat"
There are no "unique" or "rare" habitats in the Pigeon River between the Canton
Mill and Waterville Reservoir, the reach affected by the thermal discharge (see habitat
description in Appendix B).
3.2.11. Habitat Former Alterations
The principal habitat former is the hornleaf riverweed Podostemum ceratophyllum
(§3.4.4). The study noted presence or absence at the standard collecting sites, but did not
seek out the shallow bedrock or large boulder habitat generally preferred by this
macrophyte. Podostemum was found at three of four reference sites upstream of the Mill
in the Pigeon watershed and at both Swannanoa River reference sites. It was not found in
the thermally affected reach of the river between the Mill and Waterville Reservoir. It
was found at the two most downstream sites in the Pigeon River in Tennessee. As this
was the first survey to include Podostemum, there is no history to indicate temporal
trends. Its absence from the thermally affected reach may be related to the generally
smaller riverbed sediment size in the reach than at other sites and less forested land cover,
as reported elsewhere in the southern Appalachians (Argentina et al. 2010). Its lack
below the Mill does not appear to have diminished the abundance of macroinvertebrates,
which normally would use the macrophyte as habitat.
3.2.12. Nuisance Species Abundance
There has been no increase in abundance of nuisance species in the Pigeon River
downstream of the Mill due to the thermal discharge (Appendix B). Certain nuisance
periphyton growths, especially blue-green algae (cyanobacteria) have been found to
dominate the periphyton in thermal discharges elsewhere, but have not been abundant in
the Pigeon River downstream of the Mill, where they occurred in a short distance of the
zone of initial mixing (§3.2.16). Non-native Asiatic clams are considered a nuisance in
some waters, especially those with industrial water intakes that can be clogged by clams
and loose shells. These clams are expanding their distribution up tributaries of the
Tennessee River, and have reached the Mill. But their abundance is similar to other
rivers (e.g., the Little Tennessee River) (§3.4.1.3). The non-native common carp, which
can be a nuisance in some waters where it is abundant, is not abundant in the Pigeon
River downstream of the Mill. Its abundance has been declining over the years of
sampling (1980s to 2012) under the current and previous permits, which is a favorable
trend (§3.3.12).
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3.2.13. Zone of Passage
The zone of initial mixing for the Mill's thermal discharge provides a zone of
passage along the eastern side of the river for movement of fish and invertebrates. There
are no truly migratory fish species in the Pigeon River, so this issue is significant only for
the normal upstream -downstream movements of so-called resident species and
downstream passage of drifting eggs and larvae or invertebrates. The thermal plume
hugs the western shore at all flows (most pronounced at high flows), and gradually mixes
horizontally with the cool water coming from upstream (Appendix A, Figures 75-79).
This thermal pattern had been observed in previous studies, but was measured and
modeled in detail in 2012. It is clearly visible in Figure 76 of Appendix A. By the time
horizontal mixing has been mostly accomplished at the railroad bridge or Fiberville
Bridge, mixed temperatures have declined to levels that would not inhibit movements
based on upper avoidance temperatures for fish. Organisms drifting downstream through
the heated plume would experience non -lethal exposure durations of generally one
minute or less. Drifting organisms in approximately one quarter to one half of the river
width would see only slight and tolerable temperature elevations at all flows.
3.2.14. Change in Commercial or Sport Fisheries
Although there are no commercial fisheries in the Pigeon River, sport fisheries are
directed primarily to smallmouth bass. Smallmouth bass are moderately abundant
throughout the Pigeon River both upstream and downstream of the Mill (§3.3.7;
Appendix B). Their population has been increasing during the period of the current
permit, which is a desirable trend. Both the native rock bass and non-native redbreast
sunfish are abundant and popular sports panfish (§3.3.5 and §3.3.6, respectively). The
combined abundances do not differ greatly from those found in reference areas. The
relative abundance of rock bass and redbreast sunfish is trending toward the higher ratios
for native rock bass seen in reference areas, a favorable long-term trend under the current
and previous permits. Historical abundance of redbreast sunfish has likely been
stimulated by high levels of reproduction in small impoundments upstream of the thermal
discharge.
3.2.15. Magnitude and Duration of Thermal Effects
Habitat exclusion from the warmest part of the zone of initial mixing on the west
side of the river between the discharge and the downstream railroad bridge (Appendix A,
Figures 75-79; -150 ft out of a thermally affected reach of -22 miles) would occur only
in a few weeks of summer, based on thermal studies (Appendix A) and the upper
avoidance temperatures of fish species found in the Pigeon River (§3.3; Appendix B).
Periphyton composed primarily of blue-green algae with chironomid larvae (a typical
summer periphyton community in water over 32°C), occurred only in a short (<150 ft)
portion of the zone of initial mixing between the outfall and the downstream railroad
bridge. This community would have persisted only for a few weeks in summer, based on
water temperatures (Appendix A).

3.2.16. Sub -lethal or Indirect Impacts
Sublethal or indirect effects of the thermal discharge on the aquatic biological
community (such as changes in metabolic rates, behavior, reproduction, or disease)
would be expressed in individual body condition (especially for fish) and the species
diversity and abundance of the community described in Appendix B and other parts of
section 3). Incidence of disease is more directly measureable, however. In 2005 and
2012, there was a very low percentage of fish with morphological anomalies or evidence
of disease (Wilson and Coutant 2006; Appendix B). Anomalous fish have been <1 %.
The distribution of the anomalies among stations suggested only sporadic incidence
across the basin.
Body conditions of fish in the thermally affected zone are good, indicating lack of
sublethal or indirect effects. Collectively, relative weight (Wr) values indicated that: (1)
the condition of rock bass, smallmouth bass, redbreast sunfish, and bluegill from the
Pigeon River is comparable to the condition of these species from other areas in the
Southeast, and (2) the condition of these species downstream of the Canton Mill in the
thermally affected portion of the river as well as the cooler downstream portions of the
river were considered to be good. Wr values for fishes from the Pigeon River were within
expected ranges for this area. Furthermore, Wr values downstream of the Mill were
typically comparable to those upstream of the Mill and that the majority of the target
species are in good condition.
3.2.17. Interaction of Thermal Discharge with Other Pollutants
The Canton Mill's thermal discharge can contain other pollutants at permitted
levels, which might interact with warmer temperatures to enhance detrimental effects. In
addition to substances produced in the processes for making paper, the Mill treats the
municipal sewage from the Town of Canton. The ambient Pigeon River already contains
some polluting substances, mostly derived from the agricultural and rural -residential
watershed. There are 15 individual NPDES wastewater permits in the Pigeon River
subbasin in North Carolina, with a total flow of 37.13 MGD. Three are permitted to
discharge one million gallons per day or more of treated wastewater: the Canton Mill
(including Town of Canton wastewater; 29.9 MGD), Waynesville wastewater treatment
plant (WWTP; 6 MGD; PRM 54.5), and Maggie Valley wastewater treatment plant
(WWTP; 1 MGD; discharging to Jonathan's Creek entering the Pigeon River at PRM
46.0). There are 11 permitted trout farms in the basin with small discharges. Although
the ultimate test of interactions is the status of the biological community of the river
(Appendix B), this section briefly examines pollutants that might interact with warmer
water.
Dissolved Oxygen. The thermal discharge would not be a cause for, or affected
by, low dissolved oxygen (DO) because the North Carolina state standard for DO is met
downstream of the Mill. Over a period of review (January 1, 2004 - December 31, 2008)
the daily average DO did not drop below North Carolina's standard of 5.0 mg/L for Class
C streams at any of the six instream monitoring stations downstream of the Mill (NC
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DENR 2009). Maintenance of the state standard is a requirement of the permit. Oxygen -
consuming substances are in the ambient river flow upstream of the Mill and in the Mill's
discharge. Evergreen's permit contains limits for daily maximum 5-day biochemical
oxygen demand (BODO in its effluent, a monitoring requirement for Chemical Oxygen
Demand (no standard has been set by North Carolina), and a minimum effluent
concentration of 6 mg/L DO. To ensure that the instream standard is met, Evergreen
conducts routine upstream and downstream monitoring as required by its permit and
maintains oxygen injection facilities in the effluent and 0.9 and 2.1 miles downstream, to
be used as necessary.
Color. The thermal discharge contains dissolved and colloidal material that gives
the water some color. Color has not been shown to affect aquatic life beyond some
minimal shading for the primary producers (periphyton and macrophytes) in deep water.
Color is limited by the current permit to an annual average of 38,020 lb/day.
Temperature elevation should not affect the color or any of its affects on aquatic life.
Mixed Toxicants. It is unlikely that there would be interactions between added
heat and chemical constituents of the mixed chemical and thermal discharge. The facility
has consistently passed the chronic toxicity test at 90% effluent (NC DENR 2009).
Rapid dilution of the effluent in the river (Appendix A) greatly reduces the
concentrations of mixed toxicants. The small temperature increases in the river beyond
the zone of initial mixing, and the rapidity of mixing in the warmest zone ensure that
thermal and chemical interactions would minimally affect aquatic life.
Individual toxicants. No detrimental interaction is expected from individual
toxicants and elevated temperature at temperatures and exposure durations seen in the
Pigeon River. The NC DENR (2009) evaluated several individual toxic substances in the
Mill's discharge and found them not to exceed state water quality standards. Cadmium
and silver were always below detection levels and thus removed from the monitoring
requirement. Zinc "does pose a reasonable potential to cause an exceedence" of the
action level standard, but the environment would be protected by the mixed effluent
toxicity analyses. Monitoring for zinc was reduced to semi-annually. Ammonia is
monitored mostly for its potential to affect instream dissolved oxygen. The facility has
shown no presence of dioxin since 1989, although EPA requires monitoring of water for
dioxin and dibenzofuran isomers. Each of the two bleach plants at the Mill is
individually monitored for dioxin. Periodic fish tissue analysis for dioxin in fish from the
Pigeon River -Waterville Reservoir has continued in accordance with the May 2010
NPDES permit for the Mill (Henry and Wilson 2012). All concentrations in fish tissue
fillets remain below the NCDHHS 4 ppt TEQ action level for fish consumption advisory.
The advisory was lifted in January 2007.
Total Suspended Solids (TSS). Suspended solids would not interact detrimentally
with slightly elevated temperatures observed in the Pigeon River downstream of the Mill.
Values of TSS in the effluent are limited by the permit at levels more stringent than
federal effluent guidelines (NC DENR 2009). The TSS naturally varies markedly in the
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Pigeon River due to rainfall events and upstream erosion of agricultural and residential
land.
Acidity/alkalinity (pH). The pH of the effluent and at instream monitoring
stations is limited to the natural range of 6.0-9.0. No detrimental interaction with
elevated temperature is expected for biota within this range.
Conductivity. This measure of the concentration of dissolved materials is
monitored regularly at Fiberville Bridge and regulated according to a Class IV facility
(NC DENR 2009). The thermal discharge increases the conductivity of the river, but not
above natural levels seen regionally. No interactions with slightly elevated temperatures
are expected.
Adsorbable Organic Halides (AOX). Pursuant to the federal Cluster Rules (40
CFR 430 Subpart B) for the Pulp and Paper industry, monitoring and limits for AOX
have been established for the Mill (NC DENR 2009). By meeting these requirements, it
is assumed that there would be little interaction between slightly elevated temperature
and chlorinated organic materials.
Chloroform. Chloroform limits for the Mill's bleach plants are based on the EPA
promulgated Effluent Guidelines for the Pulp, Paper, and Paperboard Point Source
Category (NC DENR 2009) and thus chloroform is assumed to not interact detrimentally
with slightly elevated temperatures in the river.
Chlorinated Phenolics. Per 40 CFR 430.24, the daily maximum limits for 12
chlorinated phenolics are less than the minimum level as specified in 40 CFR 430.01 (NC
DENR 2009). Thus, it is assumed that they will not interact with slightly elevated
temperatures in the river.
Organic Enrichment, Nitrogen and Phosphorus from WWTPs. Elevated
temperatures could interact with nutrients and organic matter from the WWTPs for
Waynesville and Maggie Valley, as well as any of these substances that pass through the
Mill's treatment facilities from the Town of Canton. Unless found in excess, for which
there is no evidence, these substances would enhance biological productivity of the
mainstem river. The Waynesville and Maggie Valley influences would occur
downstream of the confluences of Richland Creek and Jonathan's Creek, respectively,
with the mainstem Pigeon River. At those points, the temperature elevations would be
small (Appendix A) and thus the temperature interactions should be slight.
3.2.18. Reference Area Comparisons
Comparisons were made between nine thermally affected sites downstream of the
Mill to Waterville Reservoir and six reference sites, four of which were in the Pigeon
River above the Mill and its two main branches, East Fork and West Fork. Two
reference sites were in the lower Swannanoa River, an adjacent watershed.
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Aquatic plants
Two components of aquatic plants were studied, periphyton and macrophytes.
Periphyton was present at all stations, with little indication of trends either between
reference and thermally affected stations or among thermally affected stations.
Macrophytes were well distributed through the river but not present at all stations.
Macrophytes were not seen at the West Fork Pigeon River site and four of 15 sites
on the mainstem: Thickety (PRM 61), Golf Course (PRM 52.3), Ferguson Bridge (PRM
48.2), and Jonathan's Creek (PRM 46.0). A species of interest, Podostemum, was found
in three of four reference stations upstream of the Mill, both stations in the reference
Swannanoa River, and two of three stations in the Pigeon River in Tennessee, but not in
the thermally affected reach between the Mill and Waterville Reservoir. Macrophytes
have not been abundant in the Pigeon River both above and below the Canton Mill since
the hurricane -generated floods of 2004, although the beds appear to be recovering.
Macroinvertebrates
Macroinvertebrate bottom -dwelling organisms were present and diverse in all
study sites, both thermally affected and reference. Total taxa numbers in the six Pigeon
River basin reference sites (ave. 59.5, range 43-91) were similar to the nine thermally
affected sites (ave. 57.1, range 47-66). The two warmest sites (PRM 63.0 and 61.0) had
more taxa than the average number of species found in all of the thermally affected sites,
and exceeded two of the upstream reference sites (PRM 64.5 and West Fork) and both
Swannanoa River sites. There was no trend in taxa numbers from the warmest to coolest
among the thermally affected sites in the Pigeon River mainstem.
Numbers of pollution sensitive EPT (Ephemeroptera, Plecoptera and Trichoptera)
were somewhat lower in the thermally affected reach than in the six reference sites.
Reference area EPTs averaged 27.2 (range 8-47) whereas the average number of EPT in
the thermally affected reach was 20 (range 14-31). The lowest EPT in the thermally
affected reach was higher than the lowest of the reference sites in the Swannanoa River.
There was a slight, but not uniform, trend toward more EPT in the cooler portions of the
thermally affected reach, although the lowest numbers were in the middle (PRM 55.5
with 15) and downstream (PRM 48.2 with 14) stations.
The Index of Biotic Integrity for macroinvertebrates (NC protocol), which
combines many factors representing a balanced, indigenous community of a mountain
stream, was somewhat better on average for the six upstream reference areas (ave.
4.57=Good; range 3.88-5.05) than for the thermally affected areas (ave. 5.79=Fair; range
4.69-6.70). The NC protocol is for mountain streams and it should be recognized that
many of the thermally affected stations are slowly moving, silty habitats unlike mountain
streams.

Fish
The shallow -water fish community downstream of the Canton Mill obtained by
electroshocking in water suitable for wading is not markedly different from reference
stations in the upper Pigeon River watershed and the Swannanoa River with similar
habitat. The exception is for lower abundance or absence of some small bottom -dwelling
species now subject to mostly successful reintroduction (Appendix Q. Pigeon River
stations below the Mill appear to be within the variability among the reference sites for
most mobile fish species.
Smallmouth bass, a prime sports fish, is more abundant in the Pigeon River
downstream of the Canton Mill than in reference stations. It was found at all nine
mainstem shallow -water stations between the Mill and Waterville Lake (average 10.3
smallmouth bass per station excluding young of the year — 63 at PRM 63 and 94 at PRM
52.3). The six reference stations averaged 2.7 smallmouth bass per station, range 0-6.
Rock bass, a sports panfish, was found at all stations sampled, including upstream
reference sites in the Pigeon River basin, thermally affected river sites in North Carolina
and the two Swannanoa River reference sites. Thermally affected reaches were not
markedly different from reference sites. Reference sites in the Pigeon River basin
averaged 23 rock bass per site (range 8-48), while the Swannanoa River reference
stations averaged 11 (range 2-20). Stations in North Carolina between the Mill and
Waterville Reservoir averaged 10.2 (range 1-20).
Redbreast sunfish, a non-native sports fish that has expanded its distribution
throughout the Southeast, is abundant in the reference locations as well as in the Pigeon
River downstream of the Canton Mill. It has been considered a warm -water competitor
of native rock bass. The Pigeon River in North Carolina downstream of the Mill had a
ratio of 5.7 redbreast to 1 rockbass (5.7:1), although the relative abundance of redbreast
sunfish was most prominent at the station closest to the Mill and within the zone of
incomplete mixing (127 redbreast sunfish for a ratio of 11.5:1). Reference stations in the
Swannanoa River had a combined ratio of 2.4:1, although the most downstream
Swannanoa station had essentially the same number of each species (22 redbreast versus
20 rock bass). Pigeon River basin reference sites had a ratio of 0.5:1. Redbreast
abundance immediately downstream of the Mill and for much of the reach to Waterville
Lake is likely influenced strongly by abundant redbreast spawning observed in the small
impoundment just upstream of the discharge in summer 2012 (and documented
downstream dispersal of sunfish larvae in the reach upstream of the discharge by LaVoie
2007).
Trout, indicative of cold water, were found below the Canton Mill whereas they
were not found in the reference locations in the West Fork Pigeon River, East Fork
Pigeon River or Swannanoa River. Trout were found near the mouths of three tributaries
with the Pigeon River downstream of the Mill but upstream of Waterville Lake: Crabtree
Creek (PRM 49.8) had one brown trout, Jonathan's Creek (PRM 46.0) had six rainbow
trout, 14 brown trout and three brook trout, and Fines Creek (PRM 42.7) had 13 brown
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and 2 rainbow trout. The adult trout found in these small streams likely spend cooler
parts of the year in the larger Pigeon River mainstem or moving between the mainstem
and the tributaries. Where trout occur in rivers, it is common to find them at the mouths
of colder tributaries in late summer.
Shiners, as a group, are characteristic of rivers and about equally abundant below
the Canton Mill and in the reference locations. Shiners averaged 26.8 per station (range
5-69) between the Mill and Waterville Lake and also 26.8 per station (range 15-52) at the
six stream reference stations.
Darters, as a group, had lower abundance in the reach between the Canton Mill
and Waterville Lake than in reference locations. Darters below the Mill averaged 9.6 per
collection (range 2-23) whereas the reference stations averaged 75.5 (range 55-100).
This was expected because darters are slow to recolonize due to both upstream and
downstream barriers to movement, and because of this are being actively reintroduced by
the Pigeon River Recovery Project. The success of even small numbers is considered
successful reintroduction, with time required for natural reproduction and expansion of
populations.
Mottled sculpin was a species of interest in discussions following the 2005 study.
It was found at all Pigeon River basin reference stations upstream of the Canton Mill
(ranging 7-45, average 23.3) but none in the Swannanoa River reference stations. There
were three collected in the reach from the Mill to Waterville Lake (at PRM 52.3). The
mottled sculpin, an obligate stream -bottom species, may have difficulty expanding
downstream through the small impoundment upstream of the Mill.
The central stoneroller is another benthic stream species, but it apparently has had
less difficulty recolonizing the once -polluted Pigeon River in North Carolina downstream
of the Canton Mill. Between the Mill and Waterville Lake there was an average of 15.3
stonerollers per site (range 0- 94) whereas all reference stations averaged 38.8 per site
(range 8-66).
Scores for the Index of Biotic Integrity for all collected fish (IBI; TVA method)
were not greatly different in 2012 between reference stations and the stations affected by
the Mill discharge. This IBI includes 12 fish -community parameters. Reference station
scores averaged 42.3 (range 40-46) whereas the sites between the Mill and Waterville
Reservoir averaged 38.9 (range 26-46).
All fish species collected in the mainstem study sites from above Canton to
Waterville Reservoir aligned into five groups (Appendix B). One group consisted of
species (5) that were restricted to or much more abundant upstream of the Mill and
another of species (13) that were restricted to or much more abundant between the Mill
and Waterville Reservoir. The uniquely higher species richness of the thermally affected
reach could be viewed positively, although it may just reflect the higher habitat diversity
in the river reach downstream of Canton.

Several fish diversity indices showed that the average of all thermally affected
sites was only slightly less diverse than the reference sites, but that highest diversity
occurred where thermally influenced. Thermally affected averages were generally
brought down by the site closest to the Mill (Fiberville). Reference stations had an
average richness index (ave. 8.3, range 8-10) somewhat above the average for thermally
affected stations (ave. 7.1, range 3-13), but the highest richness was at a thermally
affected station. Similarly, the Shannon diversity index was higher and more consistent
in the reference stations (ave. 2.13, range 2.07-2.34) than in the thermally affected
stations (ave. 187, range 0.99-2.54) but the highest Shannon index was in the same
thermally affected station. The same pattern held for the evenness index, for which
reference stations averaged 0.79 (range 0.76-0.84) while the thermally affected sites
averaged 0.69 (range 0.41-0.89).
A principal components analysis (PCA) of the entire fish community at all
stations indicated that there was a gradient in fish species composition that produced
three distinct groups of sites that were most similar to each other: (1) all six reference
sites, including two tributaries and two mainstem sites on the Pigeon River upstream of
the Mill and both Swannanoa River sites, (2) all thermally influenced mainstem sites
downstream from the Mill to Waterville Reservoir, and (3) three TN sites downstream
from the hydropower facility. Low eigenvalues of the PCA analysis suggested low or no
statistical significance among the three groups. Statistical analyses indicated no
significant differences in species diversity between 2005 and 2012.
3.2.19. Trends Over Time
Based on the results of the 2012 study and the previous 2005 study, temperature
conditions in the Pigeon River downstream of the Canton Mill under permitted thermal
discharges do not appear to have negative impacts on aquatic life. Most indexes of the
aquatic community are improving over the time when there have been thermal
discharges, especially when compared to earlier studies (1988, 2000). Most missing
species, compared to reference sites, can be attributed to historical pollution and
geographical isolation by dams that has slowed or prevented natural recolonization.
These deficiencies are being rectified by planned and on -going reintroductions, which
have been largely successful. The most continuous data are for macroinvertebrates and
fish.
Aquatic plants consisting of periphyton and rooted aquatic plants that depend on
water transparency are present in the Pigeon River at both reference sites and
downstream of the Canton Mill. Aquatic insects typical of clean streams are found in all
stations downstream of the Mill. Native freshwater mussels have been successfully
grown in enclosures in the Pigeon River downstream of the Mill, indicating sufficiently
high water quality that reintroductions are underway by the NC DENR.
Macroinvertebrates were abundant and diverse throughout the study area in 2012.
Total taxa numbers in the four Pigeon River basin reference sites (ave. 64.3, range 43-91)
were similar to the nine sites affected by the Mill's effluent (ave. 57.1, range 47-66). The
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two warmest sites (PRM 63.0 and 61.0) had more taxa than the average number of
species found in all of the affected sites, and exceeded four of the upstream reference
sites.
When comparing total invertebrate taxa collected in the thermally influenced
North Carolina portion of the river from below the Mill to Waterville Reservoir (PRM
63.0 — PRM 42.6), there were 107 taxa collected in 2005 and 149 taxa in 2012, which is
an increase of 39%. The 2012 number does not include the five additional taxa found at
PRM 57.7, a new site added for the 2012 study. NCBI scores declined below the Mill,
however. Four of the eight NC stations rated a `Good -Fair' or `Good' score in 2012
compared to six of eight stations in 2005; the severe drought in 2007-08 is thought to
have had a significant impact of macro -invertebrate populations which may have
influenced the NCBI scores, which is an index designed for mountain streams. As noted
in the Introduction, much of the Pigeon River downstream of the Mill would not be
physically characterized as a mountain stream. Based on experimental transplants, the
thermally affected reach appears to be suitable for mussels, at least the wavy -rayed
lampmussel, a species of concern in North Carolina. No mussels had been found in this
reach in recent years.
Fish information shows that species diversity is high and improving. The species
assemblage represents typical feeding guilds indicating a favorable food chain. Species
represented include those requiring clean water. Favored riverine sports fish, such as
smallmouth bass, are abundant and increasing. Trout were found in tributary locations
below the Canton Mill in late summer that suggests riverine residence during cooler
times of year. Nuisance species such as common carp are not abundant and decreasing.
Non-native redbreast sunfish are abundant in reference streams as well as below the Mill;
their abundance downstream of the Mill is likely due to documented emigration of larvae
and young from the impoundment upstream of the Mill's discharge. Assemblages of
highly mobile species are similar in reference streams and the Pigeon River below the
Mill. Species with more localized ranges (darters, sculpins) are slow to recolonize the
once -polluted Pigeon River downstream of the Mill but are showing increases in diversity
and abundance with successful reintroductions.
Numbers of fish taxa collected in the thermally affected North Carolina portion of
the river below the Canton Mill to Waterville Reservoir (eight sites in 2005 and nine sites
in 2102, PRM 63.0 — PRM 42.6) increased between 2005 and 2012. There were 29 taxa
collected in 2005 and 37 taxa in 2012, a 28% increase. Darter species, which were
essentially absent downstream of the Mill in 1995, increased in number from 4 in 2005 to
5 in 2012, and were found in all nine thermally affected sites, whereas they were found
only sporadically in 2005. The catch of smallmouth bass increased almost ten -fold from
26 individuals in 2005 to 201 in 2012, with numerous juveniles indicating successful
reproduction. The ratio of rock bass relative to redbreast sunfish was 1:5.6 in 2012 and
1:10.2 in 2005, which represented a 45% increase in the less tolerant rock bass. In 2005,
only one intolerant fish species (rock bass) was collected in the thermally influenced
reach of the river below the Mill; in 2012, rock bass and two additional intolerant fish
species (smallmouth bass, greenfin darter) were found in the same reach.

3.3. REPRESENTATIVE IMPORTANT SPECIES (RIS)
Assessment of RIS is important for a Type III demonstration such as this. In a
standard Type II Demonstration (Predictive), the known or estimated thermal tolerances
of several RIS are compared to the measured or predicted temperature regimes in the
thermal effluent's receiving water. The thermal tolerance information comes from the
scientific literature, often from controlled laboratory studies. In a Type I Demonstration
(retrospective "no prior appreciable harm") or Type III Demonstration (combination)
both the field biological evidence from an operating thermal discharge and the known
thermal tolerances of the RIS are discussed. The Canton Mill has 28 years of operational
history under previous and current thermal variances and several sequential thermal and
biological studies, so it is appropriate to consider both predictive (RIS) and retrospective
(no prior harm) information.
The RIS were listed in Section 3.1, as presented in the Study Plan and approved
by NC DENR. This list represents more than a third of the fish species known from the
North Carolina portion of the river. Fish were selected because they have historically
been the main concern. The list includes both desirable species and those that might be
considered undesirable due to thermal tolerance or nuisance potential, and species whose
abundance or dominance might have been the result of the thermal discharge. The latter
are important indicators of system balance, as indicated in the federal regulations
(Subpart H). Common carp was chosen as it is thermally tolerant omnivore and has the
potential to become a nuisance species. Central stoneroller is the only herbivorous fish in
the river and occupies a unique place in the trophic structure. Shiners as a group are non -
tolerant pelagic-to-benthic insectivores and important prey items for sportsfish. Northern
hogsucker and black redhorse are bottom -feeding insectivores and are generally
considered to be thermally sensitive. Rock bass and redbreast sunfish represent two
important pool -dwelling, piscivorous species popular with many anglers. Redbreast
sunfish is, however, non-native, has invaded most regional streams, and is a competitor
of rock bass. Smallmouth bass is the most common gamefish in the river and is very
popular among anglers. Darters are a diverse group of bottom -dwelling insectivores that
can be common in eastern Tennessee and western North Carolina, often in locally
endemic populations. The thermal tolerance of most shiner and darter species is
unknown, but they represent important ecological links in streams and rivers like the
Pigeon River.
Considerable attention has been given since the 2005 study to biotic categories
other than fish (Section 1.5.2). Freshwater mussels, in particular, have been subject of
conservation concern and regional surveys. Crayfish also stand out among
macroinvertebrate organisms as species in need of conservation attention, and also have
been surveyed recently in the Pigeon River and region. In the wildlife biotic category,
stream -dwelling salamanders have been surveyed for the first time in the Pigeon River
basin. For this reason, Section 3.4 covers these Other Species of Interest, including
discussions of freshwater mussels, crayfish and salamanders.

For each RIS, we summarize known thermal tolerances with literature citations
and provide a summary of occurrence in the Pigeon River study area and reference
streams in prior surveys and the present one, as indications of regional assemblages
without thermal additions and trends over time. Comparisons of the affected areas with
reference sites and trends over time are important considerations in evaluating effects of
thermal discharges (EAB 2006). Each species or group description ends with a "bottom
line" summary in italics that relates the information to 316(a) criteria of protection,
propagation, diversity, sustainability, food chain relationships and potential domination
by pollution -tolerant species (Section 1.2).
3.3.1. Central Stoneroller, Camposttoma anomalum
This is one of the most common species in the Pigeon River and its tributaries. It
is a small herbivore. There is some thermal tolerance information for the central
stoneroller; the NC DENR rated it as "intermediate" for pollution tolerance. Cherry et al.
(1977) reported that it could survive for at least seven days at 31 °C, that it preferred
temperatures of 27-29°C, but avoided temperatures of 33°C. Fish acclimated to 23°C
showed loss of equilibrium at 35.8°C (Chagnon and Hlohowskyj 1989), which was
similar to field acclimation near 24°C and equilibrium loss at 37.7°C (Mundahl 1990).
Fish acclimated to 26°C showed loss of equilibrium at 37.2°C (Smale and Rabini 1995).
In field studies in Virginia, it was collected at temperatures as high as 34YC but
preferred temperatures in the mid 20s (Stauffer et al. 1976). In 1995, it was common to
abundant at all downstream Pigeon River stations except Fiberville (EA 1996). In 2000,
it was common to abundant at 5 of the 8 downstream North Carolina stations but rare at
the other three locations (EA 2001). In 2005, it was one of the most abundant species at
all stations except Hepco, where it was not found (Wilson and Coutant 2006).
Abundance below the Mill, including the warmest station at Fiberville, was often about
double that at the station upstream of the Mill, indicating highly favorable habitat and
thermal conditions. The central stoneroller was one of the species identified in the
September 7, 2007 fish kill (Appendix D), which indicates that it had been occupying the
river reach immediately downstream of the thermal discharge prior to the unusual events
that caused the kill.
In the 2012 study, the species was found at all stations, both reference and
thermally affected, except the one closest to the thermal discharge (Appendix B). It was
especially abundant in the Pigeon River basin upstream of the Mill (average 49 per
station, range 24-66), in the mainstem in Tennessee (average 50.3, range 15-74) and in
tributaries (average 31.8, range 4-42). Abundance in the Swannanoa reference site
(average 18.5, range 8-29) was nearly equal to the average in the reach between the Mill
and Waterville Reservoir (average 15.3, range 0-94). The highest concentration of this
species (94) was at PRM 59.0 (Clyde).
This common species, which is a food -chain species for larger fish, is locally
highly abundant, including sites in the Pigeon River affected by the thermal discharge.
Although average abundance in the river between the Mill and Waterville Reservoir is
less than in the reference sites of the upper basin, tributaries, and in the mainstem in
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Tennessee, the average is similar to that in the Swannanoa River reference sites. The
species is adequately protected, and its abundance indicates successful propagation and
sustainability. It is neither at risk nor overly stimulated by the thermal discharge.
3.3.2. Shiners, as a Group
Shiners are a group of small -sized species that are pelagic or benthic insectivores
that are considered non -tolerant of pollution (intermediate or intolerant). Species found
in the Pigeon River watershed include mirror shiner Notropis spectrunculus, saffron
shiner Notropis rubricroceus, silver shiner Notropis photogenic, telescope shiner
Notropis telescopus, Tennessee shiner Notropis leuciodes, warpaint shiner Luxilus
coccogenis, and whitetail shiner Cyprinella galactura. All serve as food -chain species
for larger fish and wildlife.
Members of this group are, however, quite tolerant of high temperature (Cherry et
al. 1977, Matthews and Hill 1979; Beitinger et al. 2000). For example, spotfin shiners
(Cyprinella spiloptera) suffered no mortality when held at 36°C for 7 days (Cherry et al.
1977). Matthews and Maness (1979) reported the Critical Thermal Maximum (CTM) of
the red shiner (Cyprinella lutrensis) to be 39.0°C. Field collections in Virginia found
whitetail shiners at temperatures as high as 35°C (Stauffer et al. 1976). In 1995, whitetail
shiner was common in the Pigeon River at most locations downstream of the Mill except
at Fiberville, where only two were collected (EA 1996). In 2000, it was moderately
common at all downstream stations except Hepco (PRM 42.6) where only three were
collected (EA 2001). In 2005, the whitetail shiner was present, although not abundant, at
all stations sampled (Wilson and Coutant 2006). Three shiner species, silver, warpaint,
and whitetail, were species identified in the September 7, 2007 fish kill (Appendix D),
which indicates that they had been occupying the river reach immediately downstream of
the thermal discharge prior to the unusual events that caused the kill.
Several species of shiners have been reintroduced to the Pigeon River below the
Mill in North Carolina since 2004, but not in Tennessee (Appendix Q. Mirror shiner
was the most abundantly released, followed (in order) by Tennessee, telescope, silver,
and highland (Notropis micropteryx) shiners.
In 2012, shiners of one species or another were found at every station sampled
(Appendix B). Highest diversity was in the four tributary streams (6 species), followed
by the thermally affected reach from the Mill to Waterville Reservoir (5), the Swannanoa
and upper Pigeon basin reference areas (each with 4) and lastly the Pigeon River in
Tennessee (2). They were most abundant in the Swannanoa River (average 41.5 fish per
station, range 31-52) and tributaries to the Pigeon River (average 37.8 fish per station,
range 6-98). They were slightly more abundant downstream of the Mill to Waterville
Reservoir (average 27.3, range 6-69) than upstream of Canton (average 21.3, range 17-
32). They were considerably less abundant in the Pigeon River in Tennessee (average
12.0, range 3-27). The whitetail shiner predominated in the Pigeon River, both upstream
and downstream of the Mill. Whitetail and telescope shiners were equally abundant in
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Tennessee. The Tennessee shiner was predominant in the Swannanoa River. Warpaint,
Tennessee and whitetail shiners dominated the tributaries.
Species and numbers of shiners in the thermally affected reach are on an increasing
trend under the current and previous permit conditions, demonstrating sustainability.
Shiners are more diverse in the thermally affected reach than in reference stations
upstream in the Pigeon River basin and the Swannanoa River. Numbers of individuals
are intermediate between the Swannanoa and upper Pigeon River reference stations.
The species mix differs among sampling locations. Shiners are protected and are
propagating at the thermal limits now in effect. Given the high thermal tolerance of
members of this genus, there is no evidence of thermally related long-term negative
impact to shiners as a group. The high diversity and numbers of shiners in tributary
waters indicates that their presence in the thermally affected mainstem is not the result of
heated discharges from the Mill.
3.3.3. Northern Hogsucker, Hypentelium nigricans
Northern hogsuckers are bottom -feeding insectivores. The upper lethal
temperature (ultimate upper incipient lethal temperature) of this species is 34°C, with
lethal temperatures ranging from 27 to 33°C at acclimation temperatures ranging from 18
to 30°C (Cherry et al. 1977). For fish acclimated to 15°C, the Critical Thermal
Maximum was found to be 30.8°C (Kowalski et al. 1978). Stauffer et al. (1976) collected
specimens from the New River in Virginia at temperatures as high as 35°C and reported
preferred field temperatures in summer of 26.6 to 27.7°C. This range corresponds well
with laboratory -determined final preferendum of 27.9°C reported by Cherry et al. (1977).
The NC DENR rated the species as "intermediate" in general pollution tolerance. In both
1995 and 2000, northern hogsuckers were common to abundant throughout the Pigeon
River study area (EA 1996, 2001). In 2005, the species was found in moderate numbers
at all stations sampled both upstream and downstream of the Mill (Wilson and Coutant
2006). The northern hogsucker was one of the species identified in the September 7,
2007 fish kill (Appendix D), which indicates that it had been occupying the river reach
immediately downstream of the thermal discharge prior to the unusual events that caused
the kill.
In 2012, the species was present at all stations except three: one in the Swannanoa
River, one in the mainstem Pigeon River closest to the discharge (PRM 63.0), and one
Tennessee mainstem station (Appendix B). The highest abundance at an individual site
(43) and highest average abundance (15.7, range 0-43) was in the Tennessee reach of the
mainstem Pigeon River. The species was next most abundant in tributaries of the
mainstem (average 13.5, range 5-23). Average abundance was similar in the upper
Pigeon River stations (average 4.3, range 2-7) and the reach of mainstem between the
Mill and Waterville Reservoir (average 4.6, range 0-12). They were least abundant in the
Swannanoa River reference sites (average 1.5, range 0-3).
The species' widespread occurrence in the study area, both thermally affected and
reference sites, indicates that it is adequately protected and is propagating, leading to
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sustainability. Based on the temperature tolerance as reported in the literature there
appears to be no threat to this species from the Mill's thermal discharge. Its presence
and abundance are not a result of elevated temperatures. It appears to be contributing in
moderate numbers to the diverse fish fauna throughout the thermally affected and
unaffected portions of the river and in reference areas.
3.3.4. Black Redhorse, Moxostoma duquesnei
Black redhorse is a bottom -feeding insectivore. There are no thermal tolerance
data specific to this species, although the NC DENR rated it as "intermediate" in general
pollution tolerance. Redhorse species are generally considered to be thermally sensitive
(Gammon 1976, Simon 1992). Unclassified redhorses had upper avoidance temperature
of 26°C (Gammon 1973). Walsh et al. (cited in EA 2001) reported CTM temperatures of
34.9 and 37.2°C for robust redhorse (Moxostoma robustum) acclimated to 20 and 30°C,
respectively. Results of bioassays by Reash et al. (2000) indicate that CTMs for golden
redhorse (M. erythurum) and shorthead redhorse (M. macrolepidotum) are about 35°C.
The shorthead redhorse was reported to have a final preferendum of 26-27.5°C (Yoder
and Gammon 1976) and an upper avoidance temperature of 37.2°C (Scott and Crossman
1973). Thus, redhorse appear to be more thermally tolerant than generally thought. In
1995, black redhorse were uncommon upstream of the Mill and immediately downstream
of it at Fiberville, and absent or rare elsewhere in the North Carolina portion of the study
area (EA 1996). In 2000, black redhorse were abundant upstream of the Mill, common at
Fiberville (the warmest station), and rare to uncommon at the stations further downstream
(EA 2001). In 2005, the species was common upstream of the Mill, present in low
numbers at Fiberville and Thickety below the Mill, but missing in the vicinity of Clyde
and Waynesville WWTP (PRM 54.5-59) (Wilson and Coutant 2006). It returned in low
numbers above Crabtree (PRM 52.3) and was found in low numbers at all stations farther
downstream.
In 2012, the species was found sporadically. None were found in the Swannanoa
River reference sites, while the Pigeon River reference sites had high variability (average
4.5, range 0-17). They were mostly absent in the river between the Mill and Waterville
Reservoir (average 0.8) except at two stations, Thickety (PRM 61.0 with three) and Golf
Course (PRM 54.3 with four). More were found in the Tennessee portion of the
mainstem (average 7, range 0-16). Four were collected from Jonathan's Creek.
If the distribution of black redhorse in the Pigeon River were to be negatively
influenced by temperature, one would expect it to be least abundant at Fiberville and
more abundant farther downstream. The opposite was seen in 2000, and in 2005 the
species was present in the warm reaches near Fiberville and Thickety but absent in the
middle stations. No station below the Mill matched the abundance above the Mill in
2005, however. The species was so sporadically distributed in 2012 that little can be said
other than that many stations, both affected and referenced, did not have the species
represented.
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There appears to be no real correlation of presence of this sporadically
distributed species with high temperatures. Thus, there seems to be no threat from the
thermal discharge to the long-term well being of this species or that this species'
abundance is a result of the thermal discharge. Its sporadic distribution among
thermally altered and reference sites suggests it is locally protected and is propagating.
3.3.5. Rock Bass, Ambloplites rupestris
Rock bass are pool -dwelling, omnivorous panfish important to anglers. There is
abundant thermal effects literature for this species. Young rock bass could be acclimated
to 36°C but died at 37°C (Brown 1976; Cherry et al. 1977). Carlander (1977) reported a
lethal temperature of 35°C. A CTM of 36°C was reported by Reutter and Herdendorf
(1976). A summaries of thermal preference and avoidance data from several authors
showed a final preferendum for juveniles near 26-28°C with an upper avoidance
temperature near 29.5°C (Brown 1976; Coutant 1977), although Cherry et al. (1977)
reported preferred temperatures of 27.3 to 30.6°C and that avoidance occurred at 27-36°C
depending on acclimation temperature. The optimum temperature for growth was
estimated to be 27-29°C (Jobling 1981). For spawning, the optimum range has been
reported to be 20.5-21 °C (Brown 1976) and 15.5-21 °C (Scott and Crossman 1973). The
NC DENR rated the species as "intolerant" of general pollution.
In 1995, rock bass were abundant upstream of the Mill and uncommon
downstream of it (EA 1996). This pattern was repeated in 2000 (EA 2001). In 2005, the
same pattern was present, although significant numbers were found at all stations below
the Mill, including the warmest station at Fiberville (Wilson and Coutant 2006). Ratios
of rock bass to its ecologically similar redbreast sunfish (Lepomis auritis; non-native,
pollution tolerant) have increased progressively over the series of studies (see description
of redbreast sunfish). The relative abundance of rock bass to redbreast sunfish in 2005
showed a 41 % improvement when compared to the 2000 data; between 2005 and 2012,
the ratio showed a further 45% improvement. The rock bass was one of the species
identified in the September 7, 2007 fish kill (Appendix D), which indicates that it had
been occupying the river reach immediately downstream of the thermal discharge prior to
the unusual events that caused the kill.
In 2012, rock bass were found at all stations sampled, including upstream
reference sites in the Pigeon River basin, mainstem river sites in North Carolina and
Tennessee and the two Swannanoa River reference sites (Appendix B). Thermally
affected reaches were not markedly different from reference sites and sites in Tennessee
below Waterville Reservoir. Reference sites in the basin upstream of the Mill were about
twice as high as all other sites, and averaged 23 rock bass per site (range 8-48), while the
Swannanoa River reference station averaged 11 (range 2-20). Stations in North Carolina
between the Mill and Waterville Reservoir averaged 10.2 (range 1-20). Sites in
Tennessee averaged 8.3 per site (range 3-18). Tributaries of the Pigeon River between
the Mill and Waterville Reservoir averaged 12.5, range 3-18.
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Although their abundance is lower downstream of the Mill than above it, this
reduction does not appear to be thermally related. Downstream of the Mill, rock bass in
2000 were most common at the two stations closest to the Mill (and warmest) and less
abundant at cooler stations farther away. In 2005, the catches were more evenly
distributed, but still highest at warm Thickety (PRM 61) among the NC stations. In 2012,
the catch at Thickety was nearly twice the average for the rest of the thermally affected
reach and reference sites and tributaries. Also, its abundance at the downstream stations
in North Carolina in 2000 and 2012 was not very different from the Tennessee stations
where temperature is clearly not an issue. In 2005, abundance at the TN stations more
than doubled those at the NC stations. The reasons for lower abundance at several North
Carolina and Tennessee sites than above the Mill may be the presence of less favorable
habitat (mostly bedrock) throughout much of the area and likely competition with the
redbreast sunfish that is more abundant in the North Carolina portion of the study area
below the Mill. A study of drifting larval fish, some of which may have been rock bass,
indicated higher numbers downstream of the thermal discharge than immediately
upstream of it (LaVoie 2007). Spawning was likely occurring in the low -head
impoundment upstream of the Mill, with larvae produced there drifting downstream
populating the reaches downstream of the Mill.
The distribution and abundance patterns for rock bass in the Pigeon and
Swannanoa rivers do not appear to be thermally related and therefore the thermal
discharge appears not to adversely affect the species. The trend of improving success of
the species in the Pigeon River relative to its competitor, redbreast sunfish, indicates that
the species is protected, is propagating, constitutes a sustainable population and that the
current thermal effluent limits are acceptable for this pollution -intolerant species.
3.3.6. Redbreast Sunfish, Lepomis auritis
The redbreast sunfish is a non-native panfish originally from coastal plain
watersheds in NC, but spread throughout the eastern US because of its favor as a sports
fish. It has been considered a warm -water competitor of native rock bass. It is thermally
tolerant, and its general pollution tolerance is so rated by the NC DENR. Trembley
(1960) reported an upper lethal temperature of 38.3°C when it was acclimated to 21°C.
In the field, it has been reported at temperatures as high as 39.2°C (EPRI 1981). In both
1995 and 2000, redbreast sunfish were more abundant than rock bass downstream of the
Mill than upstream of it except in Tennessee (EA 1996, 2001). In 2005, this pattern
continued, with a ratio of 10.2:1 between the Mill and Waterville Lake compared to
0.13:1 upstream of Canton (Wilson and Coutant 2006). The redbreast sunfish was one of
the species identified in the September 7, 2007 fish kill (Appendix D), which indicates
that it had been occupying the river reach immediately downstream of the thermal
discharge prior to the unusual events that caused the kill.
In 2012, the abundance of redbreast sunfish relative to rock bass has declined
from previous surveys and was similar to the Swannanoa River reference sites (Appendix
B). For all stations sampled in North Carolina and Tennessee in 2012, there was a ratio
of redbreast to rock bass of 2.6:1. Reference stations in the Swannanoa River had a
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combined ratio of 2.4:1, although the most downstream station had essentially the same
number of each species (22 redbreast versus 20 rock bass). All Pigeon River basin
reference sites had a ratio of 0.5:1 (nearly 5 times the abundance of redbreast sunfish seen
in 2005 at the single reference station upstream of Canton). The Pigeon River in North
Carolina downstream of the Mill had a ratio of 5.7:1, which was slightly over half the
relative abundance in 2005. In 2012, the relative abundance of redbreast sunfish was
most prominent at the station closest to the Mill and within the zone of incomplete
mixing (127 redbreast sunfish for a ratio of 11.5:1), although this ratio was considerably
less than in 2005 (28.5:1). Crabtree Creek yielded 16 redbreast sunfish while Jonathan's
Creek had one and the other creeks none.
The species' greater abundance downstream of the Mill had been thought to be
due to its thermophilic nature and general tolerance of pollution (Wilson and Coutant
2006). The redbreast sunfish is an active competitor in eastern waters, and it has been
implicated in out -competing and displacing the native longear sunfish over a wide area
(Etnier and Starnes 1993). It was thought to be outcompeting rock bass in the warmer
Pigeon River downstream of the Mill. A study of larval fish drift, however, indicated a
high abundance of sunfish larvae (attributed mostly to redbreast sunfish) emanating from
a low -head impoundment immediately upstream of the Mill (LaVoie 2007).
Confirmation of abundant spawning in that pool, dominated by redbreast sunfish over
rock bass, suggests that the outpouring of larval redbreast sunfish from the pool swamps
recruitment of rock bass in the river downstream of the Mill.
The species' high abundance at the Swannanoa River reference stations and its
persistent natural introduction into the river downstream of the Mill from reproduction in
the upstream pond indicate that this non -indigenous warm -water species' presence or
abundance downstream of the Mill is not attributable to the thermal discharge. With its
high thermal tolerance and its high downstream abundance under current permit
conditions, it is protected and propagating with no adverse impacts expected for this
species should the permit conditions continue. Its decline in numbers in the thermally
influenced reach relative to the indigenous rock bass is seen as a favorable trend. The
species is not a nuisance species, despite its thermal tolerance and increased abundance
below the Mill, because it is a popular species with anglers and it is not disruptive of
normal aquatic habitats.
3.3.7. Smallmouth Bass, Micropterus dolomeiu
This species is an important sports fish and for that reason there is much literature
on its thermal requirements. The upper incipient lethal temperature for larvae is 30°C
(Shuter et al. 1980) to 35.8°C (Crippen and Fahmyl981). For fry, it is about 38°C
(Brungs and Jones 1977; Wrenn 1980). For juveniles and adults, it is about 35°C (EPA
1974; Cherry et al. 1977). The Critical Thermal Maximum for fish acclimated to 26°C
was 36.9°C (Smale and Rabeni 1995). The final preferendum is about 31°C for juveniles
and adults, with avoidance temperatures of 27-36°C, depending on acclimation
temperature (Coutant 1977; Cherry et al. 1977; Spotila et al. 1979). The optimum
temperature for growth appears to be 25-29°C (Shuter et al. 1980; Coutant and
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DeAngelis 1983; McCauley and Casselman 1980; Carlander 1977). The NC DENR rated
the species as "intolerant" of general pollution.
Smallmouth bass have been gradually increasing in the thermally affected reach
of river. Despite moderate thermal tolerance, smallmouth bass abundance was uniformly
low throughout North Carolina portions of the study in 1995 (EA 1996). However, in
2000, catches of smallmouth bass were considerably higher at all locations (EA 2001),
indicating that the general conditions for the species were improving. Abundance was
lower at Fiberville, however, (the warmest station). In 2005, smallmouth bass were
reduced from the 2000 catch (likely due to severe flooding in 2004) but collected in low
numbers at all stations, with particular abundance at Ferguson Bridge (PRM 48.2) and in
Tennessee at PRM 24.9 (Wilson and Coutant 2006). The smallmouth bass was one of the
species identified in the September 7, 2007 fish kill (Appendix D), which indicates that it
had been occupying the river reach immediately downstream of the thermal discharge
prior to the unusual events that caused the kill.
In 2012, smallmouth bass was abundant in the Pigeon River downstream of the
Canton Mill (Appendix B). It was found at all nine mainstream shallow -water stations
between the Mill and Waterville Lake (average of 10.3 smallmouth bass per station
excluding young of the year— 63 at PRM 63 and 94 at PRM 52.3). The six reference
stations averaged 2.7 smallmouth bass per station, range 0-6. Three sites in Tennessee
had 5, 8 and 10 smallmouth bass.
In general, smallmouth bass are present in moderate numbers throughout the
Pigeon River study area and reference sites, regardless of the thermal discharge. The
population is increasing from earlier studies, indicating protection, propagation and
sustainability. Population numbers of this species elsewhere often fluctuate according to
the success of reproduction, which is greatly affected by timing of stable river flows in
spring. Even with the reduced numbers in 2005, there appears to be no adverse impacts
on this species under existing conditions.
3.3.8. Darters, as a Group, Etheostoma spp.
Darters are a diverse group of small, bottom -dwelling insectivores. They tend to
be locally endemic due to restricted movement and small body sizes, but serve the same
general ecological functions. Darters found in the Pigeon River studies are: banded
Etheostoma zonale, fantail E. flabellare, gilt Percina evides, greenfin E.
chlorobranchium, greenside E. blennioides, redline E. rufilineatum, snubnose E.
tennessense, Tuckasegee E. gutselli, and tangerine P. aurantiaca (Appendix B).
Because darters are a diverse genus (>150 described species), they would be
expected to exhibit a fairly wide range of temperature requirements and show a complex
relationship as a group to the thermal discharge of the Canton Mill. The CTM for four
species of 15°C-acclimated darters, greenside, rainbow (E. caeruleum), fantail, and
johnny (E. nigrum) were all about 31-32°C (Kowalski et al. 1978), and higher
acclimation temperatures would be expected to result in higher CTM values. Various
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Etheostoma species acclimated to 20°C and above exhibited CTM values of 32-38°C
(Beitinger et al. 2000). The optimum temperature for rainbow darter was reported to be
17-18.5°C (Scott and Crossman 1973), although the final preferendum was estimated to
be 20°C (Floyd et al. 1984). Greenside darter has been collected as high as 35°C
although their preferred temperature is considerably lower as peak numbers were
collected at 26.6-27.2°C in one year but without correlation with temperature in another
year (Stauffer et al. 1976). Final preferendum for johnny darter was 11-22°C (Wyman
1981) with larvae having 17-20°C (Floyd et al. 1984) or 24.5°C (Marcy 1976). Marcy
(1976) reported larval johnny darter's upper avoidance at 24.5°C. Optimum for the
fantail darter spawning and hatching was reported to be 21.1°C (Scott and Crossman
1973). The NC DENR rated the darters from "intolerant" (gilt, tangerine, greenfin, olive)
to "intermediate" (all others).
In 1995 and 2000, three species of darters were common upstream of the Mill
(greenside form gutselli (now called Tuckasegee darter), greenfin, and tangerine) (EA
1996; 2001). In 2000, these three species were all collected downstream of the Mill,
although greenside gutsellilTuckasegee was widely distributed but rare to uncommon,
while greenfin and tangerine were rare downstream of the Mill. The temperature
tolerances are not known for these species. Greenside gutselli/Tuckasegee and greenfin
are largely restricted to the Blue Ridge physiographic province so it is reasonable to
assume that they are cold -water forms (EA 2001). In the 2001 study report, it was
hypothesized that continuation of the thermal limits for the Mill may prevent or retard
establishment of greenfin and perhaps tangerine in the North Carolina portion of the
mainstem (EA 2001). However, both species were found in the warmest stations in 2005,
Fiberville and Thickety, suggesting that recolonization from upstream is occurring and
that the thermal and other habitat conditions downstream of the Mill are suitable for the
species (Wilson and Coutant 2006).
Four species of darters (greenside form newmani (now called E. blenioides),
redline E. rufilineatum, snubnose E. simoterum, and logperch P. caprodes) were common
to abundant in the Tennessee portion of the Pigeon River mainstem in the 2000 studies.
In 2005, three of them (not logperch) were found uniquely in the Tennessee reach,
although the snubnose darter was represented by only one specimen (Wilson and Coutant
2006). Temperatures there are not particularly different from those in the lower portion
of the North Carolina segment. Three darter species, tangerine, Tuckaseegee, and
greenfin, were among the species identified in the September 7, 2007 fish kill (Appendix
D), which indicates that they had been occupying the river reach immediately
downstream of the thermal discharge prior to the unusual events that caused the kill.
Darters have been reintroduced to the Tennessee portion of the Pigeon River since
2001 and the North Carolina portion since 2005 (Appendix Q. In Tennessee, gilt,
bluebreast E. camurum, blueside E. jessaie, stripetail E. kennicotti and tangerine have
been released. Gilt darters were the most released in North Carolina, although banded
darters began to be released in 2009.

In 2012, some species of darter was collected at all stations, including stations in
the thermally affected river between the Mill and Waterville Reservoir (Appendix B).
Diversity of darter species was highest (6 species) in the thermally affected reach
between the Mill and Waterville Reservoir (Swannanoa reference sites and tributaries
each had 5 species, the Tennessee Pigeon River 4, and upper Pigeon River basin
reference stations 3). Darters were abundant in the upper Pigeon River basin reference
stations (average 77 per station, range 55-100), the Swannanoa River reference stations
(average 74.5, range 55-94), and in the Tennessee portion of the Pigeon River mainstem
(average 81.3, range 38-115). They were noticeably less abundant in the mainstem
downstream of the Mill (average 9.8, range 2-23) and in the tributaries (average 11.5,
range 4-27). Greenfin was the most prominent darter in the upper Pigeon River reference
stations followed by Tuckasegee and a few tangerine. The redline darter was the most
prominent species in the Tennessee segment of the river, with greenside and snubnose
making up most of the rest. In the Swannanoa reference stations, the fantail and redline
darters predominated, with some banded, greenside, and gilt collected at one station. In
tributaries, Tuckasegee darter was found at all stations, greenfin was incidental in
Jonathan's and Richland creeks, and gilt was found in only Richland Creek. Below the
Mill, there was a mixture of species showing some longitudinal separation. Greenfin was
found closer to the Mill (stations at PRM 55.5-63.0) whereas banded and gilt were in the
lower reaches (PRM 48.2-57.7). Tuckasegee darter, however, was found at all stations
except PRM 61.0. Habitat, temperature, other water quality factors, locations of
reintroductions, or random dispersal may be responsible for the longitudinal differences
among species, which cannot be resolved with available information.
Although numbers of darters in the thermally affected reach of river remain lower
than at reference sites or in the Tennessee portion of the river, the species, numbers and
distribution are improving with time, demonstrating sustainability and propagation. This
indicates that ability to recolonize, rather than thermal sensitivity, is the main reason for
their lower abundance in the North Carolina reach. Site fidelity of darters is high with
few long-range excursions; 80-97% of individuals remained in the habitat patch of their
capture for up to one year, with average distance moved being less than 200 meters
(Dammeyer et al. 2013). Direction of movement was found to be biased towards
upstream by both younger and older fish. Upstream movement from Tennessee is
blocked by Walters Dam. Colonization from upstream reaches would be slow since the
stream habitat required by darters is interrupted by the pool behind the low -head dam in
Canton. Darter reintroductions are underway, sponsored in part by Evergreen, which
should further accelerate the trend toward increased darters.
Species and numbers of darters in the thermally affected reach are on an
increasing trend under the current permit conditions, demonstrating sustainability.
Darters are more diverse in the thermally affected reach than in reference stations,
although numbers remain lower, likely due to slow recolonization from historical
pollution. The species mix differs among sampling locations. Some avoidance of
warmest areas is probable under extremely warm thermal conditions. Darters are
protected and are propagating at the thermal limits now in effect. Darters are not
species whose presence and abundance would be fostered by the thermal discharge.
-79-

3.3.9. River Chub, Nocomis micropogon
The river chub is a native, pelagic omnivore. There is little thermal tolerance
information available for this species, although the NC DENR rated it as "intermediate"
in overall tolerance to pollution. The Critical Thermal Maximum for 15°C-acclimated
river chub was 30.9°C (Kowalski et al. 1978; Spotila et al. 1979). Spawning has been
observed in the range 19-28°C (Carlander 1969). Initial nest -building behavior was
observed 11.9-20.6°C (Brown 1976). Based on this limited information, it appears that
the species is moderately tolerant of warm temperatures.
In the 2005 study, it was the most abundant species in the station upstream of the
Mill, was found in moderate numbers just below the Mill at Fiberville, but disappeared
for the next three stations (Wilson and Coutant 2006). It reappeared at PRM 54.5 and
was fairly abundant at Ferguson Bridge (PRM 48.2). It was not found in the Tennessee
portion of the Pigeon River. Its absence from PRM 55.5 to 61 in 2005 was thought to be
related to temperatures, although warmer temperatures occurred at Fiberville. Catches at
Fiberville may have been from the cooler side of the river, however.
River chub have been introduced to the Pigeon River in Tennessee only
(Appendix Q. Tennessee releases of 226 fish occurred between April 2005 and August
2011 to augment existing populations.
In 2012 (Appendix B), it was abundant at reference stations upstream of the Mill
(average 27.8, range 17-51), in tributaries (average 24.5, range 2-50), and especially in
the Swannanoa River reference sites (average 99.5, range 81-118). In the reach from the
Mill to Waterville Reservoir, it was absent from the uppermost four stations and then
gradually increased going downstream to a high at Ferguson Bridge (PRM 48) before
declining again at Hepco (PRM 45.3). The species was not found in the Tennessee
portion of the Pigeon River. Habitat changes near the Mill since the 2005 study may be
responsible for lack of this species at Fiberville.
The 2012 gradient of increasing abundance with distance downstream of the Mill
and the low average numbers there relative to reference sites would suggest a negative
influence of the discharge, thermal or other, or of the habitat in the reach near the Mill,
on this species. Its ecological functions are being met by other species.
3.3.10. Mottled Sculpin, Cottus bairdi
The mottled sculpin is a native, bottom -dwelling insectivore that appears to be a
cold -water species. Fish acclimated to 15°C had a CTM of 30.9°C (Kowalski et al.
1978). The final preferendum has been reported to be 16.5°C (Coutant 1977) and 16.7°C
(Wyman 1981). The optimum temperature for spawning is said to be 12.8°C with a
range of 5-16.1°C and suitable hatching 7.8-17.3°C (Brown 1976). Scott and Crossman
(1973) report optimum spawning at 10°C. The NC DENR rated it as "intermediate" in
general pollution tolerance.

In 2005, the mottled sculpin was fairly abundant above the Mill, and occurred
incidentally at the next three stations downstream (Wilson and Coutant 2006). It was
missing from below Clyde to Waterville Reservoir and only one specimen was found in
Tennessee. In 2012, it was found almost exclusively in the reference stations in the
Pigeon River upstream of the Mill (average 23.3, range 7-45). Three specimens were
captured at Golf Course (PRM 52.3) in the reach between the Mill and Waterville
Reservoir while none were captured in tributaries, Swannanoa River, or in the mainstem
in Tennessee.
This cold -water species appears unsuited for lower -elevation mainstems and
tributaries in the Pigeon and Swannanoa watersheds, regardless of the thermal
discharge, as evidenced by absence in the Swannanoa reference locations and tributaries
of the Pigeon River downstream of the Mill. The species is an unsatisfactory RIS due to
its low abundance.
3.3.11. Banded Sculpin, Cottus carolinae
The banded sculpin is also a native, bottom -dwelling insectivore. No thermal
tolerance information was found for the banded sculpin, although the NC DENR rated it
as "intermediate" in general pollution tolerance. It occurred only in the Tennessee reach
of the Pigeon River in 2005 (Wilson and Coutant 2006), where it also was abundant in
previous studies (EA 1988, 1995, 2001). It was found in the reach from the confluence
of the East Fork and West Fork to the Mill in only one study (EA 1996).
In 2012, it was not found in the Pigeon River at reference stations or thermally
influenced stations. It was also not found at the Swannanoa River reference stations or
in tributaries to the Pigeon River from the Mill to Waterville Reservoir. It was found
only in the Tennessee portion of the Pigeon River, where it averaged 52 per station, range
36-73. This continues the pattern in previous studies.
The species has essentially no exposure to the Mill's discharges. It is not found in
the reference locations and found only in the Pigeon River in Tennessee. Based on this
limited thermal tolerance information and limited occurrence, it is not a good species to
be considered as an RIS for the Mill's discharge.
3.3.12. Common Carp, Cyprinus carpio
The common carp is a thermally tolerant species that can become a nuisance
when overly abundant because its feeding activity disrupts aquatic habitats for other
species. Although collected at temperatures up to 39.5°C (EPRI 1981), its upper
avoidance temperature (juveniles and adults) was determined to be 34.5°C with a
preference for 29-32°C (summarized by Coutant 1977). Optimal temperatures were
reported to be in the range 33-35°C (Gammon 1973). Depending on acclimation state,
the lethal temperature after prolonged exposure is 36-40°C (EPRI 1981). In rapid heating
tests for Critical Thermal Maximum, small and large carp acclimated to 23YC showed
irreversible loss of equilibrium at 38-39°C (Spotila et al. 1979). The lethal temperature

for eggs is 35°C (Jinks et al. 1981) and for larvae is 36-38°C (Talmage 1978). The NC
DENR rated the common carp as "tolerant."
The common carp has been moderately common below the Mill, but not
excessively so (EA 1996, 2001, and Wilson and Coutant 2006). Its abundance appears to
be declining in the thermally affected reach. In the 2005 study, 33 carp were collected,
which represented only 1 % of the total catch. It was not collected upstream of the Mill in
2005, and fewer than 10 were collected at each North Carolina station except Hepco
where none were collected. In 2012, 22 carp were collected, all in the Pigeon River. It
was not collected at reference stations upstream of the Mill or in the Swannanoa
reference stations. It appeared in five of nine stations between the Mill and Waterville
Reservoir, with an average catch of 1.9 per station (range 0-6). Few carp could be found
in Waterville Reservoir for sampling for dioxins in fish (Henry and Wilson 2006). The
state has determined that carp are not abundant enough to be considered a nuisance
species in the Pigeon River (memo from Bryn Tracy dated 17 March 2000, as reported in
EA 2001).
Although the thermally tolerant and potentially nuisance common carp occurs
sporadically in the river downstream of the Mill, it is not abundant enough to be a
nuisance. It is not a species warranting protection and propagation. Its numbers are
declining from previous studies, indicating that the recent thermal conditions may be
reducing its sustainability.
3.3.13. RIS Summary
In summary, most RIS meet the 316(a) criteria of protection, propagation,
sustainability, and non -domination by pollution -tolerant species. For fish taxa considered
as related groups of species (shiners and darters), the criterion of diversity within the
group is also met. Only one species, the river chub, is not found at sites close to the
thermal discharge and is low in numbers farther downstream relative to reference sites.
Two thermally tolerant and less favored species, the non-native common carp and
redbreast sunfish, occur only sporadically and are declining (carp) or are less dominant
than previously found (redbreast sunfish in relation to its native competitor, rock bass).
Neither is considered a nuisance species in the Pigeon River. Two sculpin species are so
spottily distributed that they were poor choices for RIS. Several RIS will likely avoid the
near field thermal plume area for a moderate period (perhaps a few weeks) under worst -
case thermal conditions and avoid it for short periods of the time (hours or days) during
normal summer low -flow periods, based on thermal preference data. Avoidance during
the summer is not a problem for populations unless several factors occur: no alternative
habitat is available (thermal refuge, which may have been the case in September 2007),
the period of avoidance is long, fish are forced to leave critical spawning areas, or
migratory movements are blocked. None of these conditions appear to be present under
normal or normally low flows.
Among the RIS, the darters (as a group) are conspicuously reduced in numbers
throughout the North Carolina reach downstream of the Mill (although present at all

stations). As noted in previous study reports, the improvements to both water quality and
the biota should allow darter species to recolonize the North Carolina reach downstream
of the Mill (EA 1996, 2001; Wilson and Coutant 2006). This seems to be occurring
based on the 2012 studies and the September 2007 fish kill report (Appendix B,
Appendix D). It remains likely that the somewhat more thermally tolerant Ridge and
Valley assemblage of darter species would naturally come to replace the Blue Ridge
assemblage in lower reaches of the Pigeon River. However, because Walters Dam
prevents upstream movement of the Ridge and Valley assemblage from the Tennessee
portion of the Pigeon River, the artificial recolonization effort is important (Appendix Q.
Consistent with previous reports, the species that are somewhat thermally
sensitive (e.g., black redhorse, Tuckasegee darter, northern hogsucker) have either
maintained population levels in the river or increased noticeably since 1995. Similarly,
smallmouth bass numbers have increased and strong reproduction is evident in large
numbers of young fish. These improvements would not have occurred if elevated
temperatures allowed under the current permit were a significant limiting factor.
3.4. OTHER SPECIES OF INTEREST
Species other than the approved RIS (all fish) have been subjects of discussion
and debate related to Pigeon River recovery. Freshwater mussels are of special interest,
particularly the Appalachian elktoe Alasmidonta raveneliana and the wavyrayed
lampmussel Lampsilis fasciola that have been found in the Pigeon River since the last
316(a) study and demonstration (Fraley and Simmons 2006; NC DENR April 2, 2012
Memorandum from E. Fleek to T. Belnick). The invasive clam Corbicula, aquatic
crayfish and salamanders were singled out for attention in the debate over issuing the
previous thermal variance. Information on the aquatic plant, Podostemum, a habitat
former for macroinvertebrates, was requested by NC DENR (April 2, 2012 Memorandum
from E. Fleek to T. Belnick).
3.4.1. Freshwater Mussels
3.4.1.1. Appalachian Elktoe, Alasmidonta raveneliana
The federal and state endangered Appalachian elktoe (NC WRC 2009; USFWS
2002; 59 FR 60324) is known only from the mountain streams of western North Carolina
and eastern Tennessee. Available information suggests that the species once lived in the
majority of the rivers and larger creeks of the upper Tennessee River system in North
Carolina, with the possible exception of the Hiwassee and Watauga River systems. In
Tennessee, the species is known only from the mainstem of the Nolichucky River. It
currently has a fragmented, relict distribution, with six surviving populations detailed in
USFWS (2002). It is federally listed "wherever found" (USFWS 2012); a recovery plan
was published in 1996 (USFWS 1996). In the Pigeon River system, a small population
occurs in small, scattered sites in the West Fork and in the mainstem upstream of Canton.
This reach supports one of the only two populations in the French Broad River system. It
inhabits relatively shallow, medium-sized permanent creeks and rivers with cool, clean,
IBM

well -oxygenated, moderately fast -flowing water. It is most often found in riffles, runs
and shallow flowing pools, with relatively silt -free, coarse sand and gravel substrate.
Stability of substrate appears critical, and the species has not been found where there are
accumulations of silt or shifting substrate unless washed there by high river discharge.
These conditions occur in moderate to high stream gradient where there is periodic
natural flooding.
The species has a thin, kidney -shaped shell reaching up to about 10 centimeters.
Juveniles generally have yellowish -brown outer shell surface, while adults are usually
dark brown to greenish -black. Rays may be prominent or obscure. It feeds by filtering
organic material from the flowing water. Reproduction is typical of most freshwater
mussels: males release sperm into the water in summer, females collect sperm through
their siphons during respiration, fertilized eggs are retained until glochidia larvae fully
develop, parasitic glochidia are released to the host fish (two sculpin species, mottled
Cottus bairdi and banded C. carolinae), glochidia are released to settle to the substrate
and transform to the largely sedentary juvenile. In the Little Tennessee River, spawning
occurred late August -mid September and brood larvae overwinter until they are released
in late April -mid May (USFWS 2005). Its life cycle has not been studied in the Pigeon
River system and it has not been propagated in captivity. The species is sensitive to
numerous pollutants and land uses associated with human occupation. It has no
economic value except as an indicator of good habitat quality.
The U.S. Fish and Wildlife Service reviewed the species in 2005 "to ensure that
the classification of the species as ... endangered ... is accurate" (Federal Register Vol. 70,
No 181, September 20, 2005; USFWS 2005). The Pigeon River population comprising
(at that time) 22.6 km (14.04 mi) was considered "restricted to scattered areas" and
"vulnerable to extirpation from a single catastrophic event, such as a major chemical
spill." The Service concluded that listing was still warranted and that additional
monitoring of the Pigeon River population was needed to determine long-term population
trends.
This species is one of two found at one sampling station upstream of Canton,
North Carolina (Fraley and Simmons 2006). Although sampling sites did not extend
downstream of Canton (their Figure 1 and Appendix Table A2-3), Fraley and Simmons
(2006) stated that "the downstream distribution of Appalachian elktoe in the Pigeon River
ends abruptly at Canton where habitat becomes unsuitable due to a small impoundment
and physico-chemical impacts from point and non -point sources."
The US Fish and Wildlife has designated stream reaches in the Little Tennessee,
French Broad, and Nolichucky river systems as critical habitats (USFWS 2002). Part of
the Pigeon River system is one of those critical habitats: "the mainstem of the West Fork
Pigeon River (French Broad River System), from the confluence of the Little East Fork
Pigeon River, downstream to the confluence of the East Fork Pigeon River, and the
mainstem of the Pigeon River, from the confluence of the West Fork Pigeon Rivet and
the East Fork Pigeon River, downstream to the N.C. Highway 215 Bridge crossing south
of Canton, NC." This amounted to 17.8 km (11.1 miles) in 2002, although additional

collections extended that to 22.6 km (14.04 mi) by 2005. The criteria correspond to the
habitat requirements noted above.
No references to thermal requirements of this species have been found.
Suitability of the thermally affected reach of the Pigeon River downstream of Canton for
its protection, propagation and sustainability has not been tested.
In the 2012 Balanced and Indigenous study, we found none of this species at
sampling sites in the thermally affected reach, in the Tennessee portion of the Pigeon
River, or at reference sites. It has been judged premature to attempt reintroduction.
3.4.1.2 Wavy -rayed Lampmussel, Lampsilis fasciola
The wavy -rayed lampmussel, a species of concern in North Carolina (LeGrand
2006; NCWRC 2009), is distributed discontinuously from the Great Lakes drainages of
Canada to Alabama and Illinois to New York (Mulcrone 2006). It is a rare occurrence in
smaller, upstream creeks or in downstream areas of larger rivers. The species is generally
found in more or less solid sand and gravel bottom in riffles and rapid waters. An adult
may reach 8 cm long and have a rounded or oval shape to its fairly thick shell. The outer
shell layer is smooth, yellow to yellow -brown, with thin wavy green rays. Older
specimens tend to be more brown. Feeding is by filtration of suspended organic material
from the water. It is sexually dimorphic, with males having a compressed shell while
females are inflated. Males release sperm into the water; eggs are fertilized via the
respiratory current and held internally in the female. The female has a distinct mantle
flap, which resembles a minnow or darter. The mimic fish lures its host fish (smallmouth
bass Micropterus dolomieu, largemouth bass M. salmoides or rock bass Ambloplites
rupestris), and the larval glochidia are injected into the fish's mouth for attachment to its
gills, where it is parasitic until release (important for dispersal). Age to sexual maturity is
not known. Gamete formation is initiated by increasing water temperatures in spring;
fertilized gametes have a gestation period of up to 10 months; most once -a -year
reproduction is presumed to occur in summer months. The species has no economic
importance other than being an indicator of good water quality. It has been cultured in
the laboratory and introduced to augment depleted stocks, particularly in Virginia and
Tennessee, with "fledgling efforts in North Carolina" (Neves 2004). There are
particularly strong recovery efforts in Canada (Young and Koops 2010).
In North Carolina, this species occurs in the Nolichucky and Pigeon Rivers
(French Broad River system), the Little Tennessee and Tuckasegee rivers (Little
Tennessee River system) and the Hiwassee River (Fraley 2002). In the Pigeon River, this
species is one of two that had been found (with the Appalachian elktoe), at stations in the
upper river above Canton, North Carolina (there was no sampling below there; Fraley and
Simmons 2006, Appendix tables A2-3, A2-10). It is believed to have occurred
historically through the lower Pigeon River in North Carolina and Tennessee as well as
most counties in western North Carolina (NCWRC 2009). Regionally, Fraley and
Simmons (2006) found this species in the nearby North Toe River (Appendix Table A2-
3) and the Toe River (Appendix Table A24).
IBM

Only one reference to thermal requirements of this species has been found.
Unpublished observations by C. Jones (Old Dominion University) cited in Dunn and
Petro (2012) noted that newly metamorphosed juveniles of the wavy -rayed lampmussel
experienced high rates of mortality during laboratory holding at 26-27°C.
Water quality downstream of Canton was shown to be suitable for survival and
growth of late juveniles of this species. Rooney (2010) conducted an in -situ
reintroduction study with captively propagated, individually marked juveniles of two
sizes placed in enclosures in the river at two sites upstream of Canton and three
downstream sites in North Carolina and monitored for one year. Survival was equivalent
whereas growth was greatest at downstream sites (the downstream site nearest Canton
and immediately downstream of the paper Mill was not significantly different from the
upstream sites). Mussels studied by Rooney were monitored through 2012 and then
released in the river (e-mail from Dr. Martin, December 5, 2012). Some of Rooney's
mussels were observed to be gravid, suggesting suitability for reproduction (e-mail from
S. Fraley, December 5, 2012).
Wavy -rayed lampmussels were introduced into the Pigeon River below the Mill
in 2011-2013 (in the vicinity of Richland Creek) by NC DENR and Western Carolina
University (§ 1.5.2.5; Appendix Q. They have also been released above the Mill and in
the Tennessee portion of the river. These introductions are being observed by the agency
and university for survival, growth and reproduction. Monitoring has identified some
survivors in Tennessee.
In the present Balanced and Indigenous study, we found no individuals of this
species at sampling sites in the thermally affected reach, in the Tennessee portion of the
river, or at reference sites. Active reintroduction programs are underway.
3.4.1.3 Asiatic Clam, Corbicula fluminea
The only mussel found throughout the lower Pigeon River currently is the
introduced and rapidly spreading Corbicula fluminea, which has an upstream extent as of
2012 at Canton with densities similar to that found in the Little Tennessee River (e-mail
from Dr. Thomas Martin to C.C. Coutant, December 5, 2012 based on an unpublished
study). The low -head dam upstream of the Mill is suspected of being a temporary barrier
to upstream spread.
The Asiatic clam is a small, light-colored bivalve found at the sediment surface or
slightly buried. The genus Corbicula is native to temperate to tropical southern Asia
west to the eastern Mediterranean Sea, Africa south of the Sahara desert, and Southeast
Asian islands south into central and eastern Australia (USGS 2013). It was first found in
the United States in 1938 in the Columbia River, possibly brought as food by Asian
immigrants. It has spread to 38 states through major river systems throughout the
continental country and Hawai'i, particularly in the Southeast. Densities have been
documented to occur by the thousands per square meter, often dominating the benthic

community. It is a filter feeder that removes particles from the water column. It
reproduces rapidly (hermaphrodites that can self fertilize), has high fecundity (up to 600-
700 juveniles per day (Aldridge and McMahon 1978) and delivers 230 µm pediveligers
that are readily dispersed (Kraemer and Galloway 1986). Its method of dispersal to such
widely separated habitats is not known, except as transported by humans (large range
extensions) and transport of juveniles by water currents (locally). The species is a
biofouler, with tendencies to clog water systems, especially power plants with thermal
discharges where warm effluents can provide a thermal refuge for cold winters. There
can be wide swings in population abundance. It is fed upon by fish and crayfish.
Upper and lower thermal tolerances are well understood. Habel (1970, cited in
Mattice and Dye 1976) acclimated clams to -23°C and exposed them for four days to
temperatures of 29 to 38°C, finding the upper incipient lethal temperature (50%) to be
34°C. The upper median thermal tolerance in laboratory tests of continuous exposure
after acclimation to 30°C was reported to also be 34°C, with initial mortalities at 30°C
and full mortality at 39°C (Mattice and Dye 1976). No clams survived attempted
acclimation at 2 and 35°C when temperatures were raised or lowered <VC/day from
-15°C well water to the desired acclimation temperature (Mattice and Dye 1976).
Karatayev et al. (2005) reported the upper tolerance limit to be 36-37°C. It has a low
tolerance for cold temperatures (initial mortalities at 2°C regardless of acclimation, but
50% mortality 150C for 30°C-acclimated clams; Mattice and Dye 1976). Cold
temperature intolerance is understood to restrict northward expansion.
In the 2012 studies, Corbicula were found at all Pigeon River basin stations up to
PRM 64.5, where there was one found. None were found at the stations in the East and
West forks. Heretofore, Corbicula appeared to have been stopped in its regional upstream
invasions by the low -head dams at Canton (§ 1.5.2.5). Highest numbers were found at
PRM 61.0 (19) and PRM 52.3 (23). All other thermally affected sites in North Carolina
averaged 4.6 (range 2-8). Numbers at the three stations in Tennessee were also low
(average 2.7, range 2-3). There were none in the Swannanoa River.
Although Corbicula is a thermally tolerant species, its presence downstream of
the Mill, while found by only one specimen upstream of the Mill, does not result from the
thermal additions by the Mill. The two sites of highest abundance do not correlate well
with river temperatures, and likely reflect local physical habitat conditions. It is a species
that is expanding its range dramatically across the U.S. It is found and expanding
upstream, in all streams in the region (unpublished surveys by Dr. Thomas Martin and
students). Abundance in the reach downstream of the Mill is similar to that in the Little
Tennessee River, which is unaffected by thermal discharges. A low -head dam just
upstream of the thermal discharge may presently be reducing upstream expansion, but the
species' expansion history elsewhere and the one specimen found above the low -head
dams suggest that it will not be much of a barrier for long. The thermal effluent could
provide a warm thermal refuge for Corbicula in the rare events when the Pigeon River
cools to below 2°C in winter.

The exotic Corbicula is expanding its range regionally and has reached above
Canton between the 2005 and 2012 surveys (one specimen). Its distribution is not
correlated well with river temperatures. Because of the ongoing regional invasion, its
presence and abundance are not amenable to comparisons between reference and
thermally affected sites.
3.4.1.4 Other Mussel Species in the Region
Other mussel species found by Fraley and associates in the region might be found
in the Pigeon River basin with more thorough sampling. They were not found in the
2012 RIP surveys or by recent surveys by others. Further surveys of mussels in the
Pigeon River watershed should be on the lookout for these species.
French Broad River system
Although the Appalachian elktoe and wavy -rayed lampmussel are the only two
mussel species identified from the Pigeon River system, Fraley and Simmons (2006)
noted four other species in parts of the French Broad River system. These have the
potential to be found in the Pigeon. They are the slippershell Alasmodonta viridis (found
in the Mills and South Mills rivers; a North Carolina Endangered Species), creeper
Strophitus undulans (Mills, South Mills, Little and French Broad rivers) and the longsolid
Fusconaia subrotunda (Little River).
Little Tennessee and Hiwassee River systems
Several remnant populations of mussel species have been found in the nearby
Little Tennessee and Hiwassee river systems (Fraley 2002) and might be found to occur
in the Pigeon River system. The littlewing pearlymussel Pegias fabula is a federal
endangered species found sparsely in both rivers. The Tennessee pigtoe Fusconaia
barnesiana is a North Carolina Endangered Species that is very rare and has been found
in both river systems. The rainbow Villosa sp. cf.. iris is a widespread species (St.
Lawrence, Mississippi, Ohio River basins) found in the Little Tennessee and Hiwassee
river systems where it is a North Carolina species of Special Concern. The slippershell
was found in the Little Tennessee River.
3.4.2. Crayfish
Crayfish are common inhabitants of rivers and streams in the Southern
Appalachians. A baseline literature and sampling survey of crayfish in the Pigeon River
watershed was conducted in 2009-2010 by David Casey B. Dunn (Dunn 2010). A total
of 1,320 crayfish specimens representing seven species were collected in the eight -month
study. Crayfish were found in nine Pigeon River tributaries, in the mainstem Pigeon
River upstream of the Mill (PRM 63.2), in the bypass reach downstream of Walters Dam,
and in the Tennessee portion of the river. No crayfish were found downstream of the
Mill in the river itself, despite reported collections there by others. Dunn describes
stream crayfish species (and their habitats) that have been found in the Pigeon River

watershed, either through historical documentation or via his survey. The stream crayfish
are: common crayfish Cambarus bartonii, Cataloochee morph crayfish C. sp. nov. (a
taxonomically undescribed species), longnose crayfish C. longirostris, big water crayfish
C. robustus, surgeon crayfish Orconectes forceps, reticulate crayfish O. erichsonianus,
non-native virile crayfish O. virilis, and non-native White River crayfish Procambarus
acutus.
In 2012 University of Tennessee collections (Appendix B), small numbers of four
crayfish species were sampled in the Pigeon River watershed with a fifth species found in
the Swannanoa River reference site. The French Broad crayfish Cambarus reburrus was
the only species found in the Swannanoa. The non-native White River crayfish
Procambarus acutus was the only species found in the Pigeon River downstream of the
Mill in North Carolina (at PRM 52.3 and 55.5; both sites with only juveniles) and at an
upstream reference site (PRM 69.5). In the Pigeon River in Tennessee, two species were
collected, the common crayfish Cambarus b. bartonii and the long nose crayfish C.
longirostris. Tributaries to the Pigeon River in North Carolina downstream of the Mill
held crayfish: Jonathan's Creek yielded the common crayfish while Fines Creek yielded
both the common and Cataloochee Morph crayfish Cambarus (Puncticambarus) sp. nov.
The White River crayfish inhabits sloughs, swamps, and sluggish lowland streams
(USGS 2013). It is common and widespread with a discontinuous native range in the
coastal plain along the Atlantic coast from southern Maine to Georgia, along the Gulf
coast from the Florida panhandle to Mexico and north in the central Mississippi valley to
the southern Great Lakes from Minnesota to Ohio. Non-native records include central
Georgia, southern Appalachians in North Carolina and Tennessee, western Pennsylvania,
the middle Hudson Valley of New York, and along the northern Maine coast. It is widely
cultivated for bait, tolerant and adaptable, often spread in bait buckets. The species was
previously documented in the Pigeon River in 2005 (PRM 59) and 2008 (PRM 52.3)
(Simmons and Fraley 2008; TVA 2009).
Temperature tolerance information is sparse for most species of crayfish. The
common crayfish C. bartonii is considered eurythermal, tolerating temperatures from
near 0 to 33-34°C. The species was reported to show significant mortality in the Stony
River, West Virginia in 2003 when maximum summer temperatures were 33°C but not in
2004 when maximum temperatures were 32°C (Hartman et al. 2010). These authors
concluded from field and laboratory tests that exposure to temperatures above 30-33°C
for >24 hours is required to cause significant mortality of C. bartoni. Laboratory studies
have determined the ultimate upper incipient lethal temperature for adult C. bartonii to be
33.8°C (Mirenda 1975) and 32.5°C for juveniles (100% mortality at 33°C but >90%
survival at 32°C; Cox and Beauchamp 1982). This species has been shown to migrate
out of warm streams into cooler tributaries in summer (Cossette and Rodriguez 2004),
which may account for finding crayfish mostly in tributaries of the Pigeon River during
summer sampling. Critical thermal maximum values for the rusty crayfish Orconectes
rusticus vary seasonally, ranging from 24°C in January to 39°C in midsummer then
falling to 33°C in November (Layne et al. 1987). The upper incipient lethal temperature
for the northwestern crayfish Pacifasticus leniusculus was 32-33°C (Becker et al. 1975).
9130

These upper lethal temperatures suggest that thermal mortality is unlikely to be the cause
of lack of crayfish in the mainstem Pigeon River. Sensitive life stages may be less
tolerant of elevated temperature, however, such as at molting (Cox and Beauchamp
1982). Cambarus bartonii breeds in spring at cool temperatures but juveniles, which
molt frequently, occur in summer. Migration to tributaries at temperatures above
preferred or other water quality effects may be involved.
The non-native White River crayfish has apparently become established in the
Pigeon River in North Carolina, both upstream and downstream of the Mill. The
population is propagating in the middle reach below the Mill, as evidenced by juveniles
found there. Native crayfish found in the Swannanoa River, in the Pigeon River in
Tennessee, and other sites in the Pigeon River basin by Dunn (2010) were not found in
the thermally affected reach or reference sites in the upper Pigeon River. Too few
crayfish were collected to speculate about protection and sustainability.
3.4.3. Salamanders
A baseline survey of stream salamander species in the Pigeon River basin was
conducted in the summer of 2009 (Maxwell 2009). Eight stations were sampled in the
mainstem Pigeon River, four upstream of the Mill and four downstream. Three stations
were also sampled in each of four tributaries, Big Creek, Fines Creek, Jonathan's Creek
and Richland Creek. A total of 53 salamanders were found at seven of the 20 stations
visited. Five of eight species of stream salamanders were found that historically had been
reported for Haywood County, NC: Blue Ridge two -lined salamander Eurycea wilderae
(the most abundant), Eastern hellbender Cryptobranchus alleganiensis, shovel -nosed
salamander Desmognathus marmoratus, blackbellied salamander, D. quadramaculatus,
and spring salamander Gyrinophilus porphyriticus. No salamanders were found in the
main channel of the Pigeon River downstream of the Mill or in two of the tributaries
(Fines and Richland creeks). Nineteen salamanders were found in the river upstream of
the Mill. Stream width, percent rubble substrate and water quality (conductivity, salinity,
turbidity, temperature) were the main features affecting salamander abundance, richness
and diversity.
Temperature tolerance literature on salamanders comes primarily from
experiments on Critical Thermal Maximum (CTM; Hutchinson 1961) and shows high
thermal tolerances. Like fish, salamanders acclimate to warmer temperatures up to a
lethal temperature. Two species of Desmognathus (D. fuscus fuscus and D.
quadramaculatus) had CTM of 32.2 and 31.4°C, respectively, when acclimated to 15°C.
Acclimation to warmer temperatures would have yielded higher CTMs. Other
salamanders were acclimated up to 35.5°C (Diemictylus v. louisianensis) and 34.0 (D. v.
viridescens), with different populations of D. viridescens from locations across North
Carolina showing CTM values of 41-43°C for warm -acclimated individuals (Hutchinson
1961). CTM values were lower in cool seasons but all were above 37°C. Amblystoma
opacum could be acclimated to 35°C. Three species of Eurycea (multiplicata, ludifuga
and longicaudata) acclimated to 15°C exhibited CTM values of 37.5, 37.2 and 37.6°C
Sealander and West 1969). Based on these results, it seems unlikely that lack of stream
"1

salamanders downstream of the Mill would have been due to upper thermal tolerances
being exceeded in summer.
Stream salamanders that were found at sites not affected by the thermal discharge
appear to be missing from the Pigeon River downstream of the Mill, based on an initial
baseline survey in 2009.
3.4.4. Aquatic Plant, Podostemum ceratophyllum
Podostemum is of special interest because it provides stable habitat for
macroinvertebrates (habitat former; Hutchens et al. 2004; NC DENR April 2, 2012
Memorandum from E. Fleek to T. Belnick). The hornleaf riverweed Podostemum
ceratophyllum is a submerged aquatic flowering plant native to eastern and upper
Midwest of North America. It is found in all North Carolina counties bordering
Tennessee, including Haywood County (USDA 2013). It thrives in open -canopy,
shallow rapids attached to bedrock or coarse bed sediments of rivers and streams
(Hutchens et al. 2004). Podostemum forms a thick mat on stable substrates, and may
also form long (> 15 cm) stems during summer. The mats and stems are a substrate for
epiphytic algae (periphyton) as well as macroinvertebrates. It is generally indicative of
high quality, oxygenated rivers (Hill and Webster 1984). Its presence and abundance has
been negatively related to a high percentage of forested cover, and it is more likely to
occur in the center of a channel in areas with larger sediment sizes, but there was no
strong support for effects of agricultural land use (Argentina et al. 2010). It often has
patchy distribution likely due to clonal growth with low seed production and poor
dispersal ability (Philbrick and Novelo 1997). Argentina et al. (2010) expected it to be
slow to recover following disturbances such as sediment scour. The species has been
reported to occur May -September at 20.0-30.0°C with a mean temperature 24.8°C in the
New River, NC and VA, with peak photosynthesis often occurring in late summer (Hill
and Webster 1984). Temperatures of 21.5-30°C accompanied large mats of hornleaf
riverweed in mid July 1999 in the Clinch River, Tennessee (Carter et al. 2000).
Podostemum has been repeatedly demonstrated to be an important substrate for
promoting benthic invertebrate biomass, abundance, and species richness (references in
Hutchens et al. 2004) and to positively influence the abundance of several fish species,
including the banded darter, which is found in the Pigeon River (Etniar and Starnes
1993). Its role as a habitat former for invertebrates has been studied in the nearby Little
Tennessee River (Hutchens et al. 2004). The study involved complete, partial or no
removal of Podostemum from portions of four bedrock outcrops at two sites. Complete
removal greatly reduced overall macroinvertebrate abundance and biomass and altered
assemblage structure, but had relatively little effect on functional structure. There was a
strong positive relationship between surface area of Podostemum and total
macroinvertebrate abundance and biomass. They estimated that P. ceratophyllum
increased surface area by 3 to 4 times over bare bedrock, which was used most
abundantly by filter feeders. The basal portion of the plants provided most
macroinvertebrate habitat and productivity.
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In the 2012 studies, presence or absence was noted at the fixed sampling stations
for fish and macroinvertebrates. Podostemum was found in three of four reference
stations upstream of the Mill, both stations in the reference Swannanoa River, and two of
three stations in the Pigeon River in Tennessee, but not at all in the thermally affected
reach between the Mill and Waterville Reservoir (Appendix B). The species was not
examined in previous 316(a) studies, so there is no available history of change. Slow
dispersal ability due to clonal reproduction and poor seed production, combined with the
Pigeon River's stresses of flooding in 2004 and drought in 2007-2008 may be limiting its
ability to recolonize the thermally affected reach. Temperature does not appear to be a
limiting factor except in the reach nearest the Mill, where temperatures in summer can
exceed the reported upper limit of 30°C reported in the literature. Despite the lack of this
habitat former, macroinvertebrate populations are high and diverse.
Podostemum is lacking in the thermally affected reach in North Carolina but
present at most reference sites, but temperatures would exceed published upper thermal
tolerance limits only in the reach nearest the Mill. The reasons for the distribution are
speculative, but may relate to availability of appropriate hard substrate for attachment at
the sampling stations. In spite of being missing in the thermally affected reach, those
stations had high and diverse populations of macroinvertebrates, which commonly use
Podostemum as habitat.
3.5. COMMUNITY BALANCE
Although "balance" in an aquatic community is a somewhat archaic term for
modern ecology, the thermally affected reach of the Pigeon River exhibits qualities that
one would attribute to the notion of balance. In general, it is at least as balanced as the
reference locations. Recognizing that no two locations will have identical habitat and
identical biota occupying it, the thermally affected sites are reasonably similar to the
range of values seen at the reference locations. That implies that the thermally affected
sites are reasonably close to what would be expected at these sites without the influence
of the thermal discharge. The exception is the site closest to the thermal discharge, which
showed a summer community composition that was somewhat less similar to the
reference and other thermally affected sites. Locations near the thermal discharge are
often considered exceptions and categorized as official "mixing zones" where usual
thermal or biological criteria do not need to be met (the Canton Mill does not have an
official mixing zone). Attributes of community balance are described in previous parts of
Section 3 and summarized in the Master Rationale (Section 4).
3.6. WORST CASE ASSESSMENT
The worst case for biological effects of the thermal discharge is likely to be the
situation that occurred in September 2007 when a fish kill occurred. The conditions at
the time of the incident were thoroughly evaluated (Appendix D). During a regional
drought and period of exceedingly high temperatures, which occurred in streams
throughout the region, there was low flow in the Pigeon River at Canton, well below the
7Q10, while the Mill's discharge remained nearly constant in temperature and volume.
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Notwithstanding discussion of a "thermal spike" in some reports of the fish kill, there
does not appear to have been an increase in Mill effluent temperature on that day or
before. Evidence suggests that river temperatures and their duration after mixing of
effluent with low river flow exceeded thermal tolerances of the fish in the assemblage
occupying the normal mixing zone between the outfall and somewhat downstream of
Fiberville Bridge. Lethally stressed fish of 13 species in the outfall area drifted
downstream and were found to about 6 km from the thermal outfall a day after the kill.
Temperatures quickly returned to non -lethal levels and fish were observed swimming in
the outfall area by the investigators in the day following the fish kill.
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4. MASTER RATIONALE
This Master Rationale, taking into account all the data and analyses in accord with
the EPA Guidance Manual (EPA 1977), concludes that the thermal discharge of the
Canton Mill, as currently permitted, has provided for the protection and propagation of a
balanced indigenous community of shellfish, fish and wildlife in the Pigeon River
downstream of the Mill's thermal effluent. The rationale is based on evaluation of
decision criteria in federal regulations implementing §316(a), the 1977 EPA guidance,
indicators of appreciable harm derived from historical decisions, and two features
stressed by the 2006 Brayton Point Environmental Appeals Board decision: 1) whether
the community of the thermally affected zone is what it would be without the thermal
discharge, based on comparison with reference locations, and 2) whether there is a trend
of decline or improvement in the community.
Each assessment element indicated strong or partial support for protection and
propagation of a balanced indigenous community in the Pigeon River downstream of the
Canton Mill and that the thermally affected reach hosts a community that is "balanced"
and similar to what would have been there without the thermal discharge (Table 4.1). All
trophic levels of the aquatic community (biotic categories) were present and examined in
the study. Diversity was high, although slightly less (but not statistically significant)
from reference stations. The community successfully sustains itself through cyclical
seasonal changes. Abundant food chain species are present. There is no domination by
pollution tolerant species except at the site closest to the thermal discharge in the warmest
months (algae and chironomids). Indigenous species are increasing over time relative to
pollution tolerant ones. Aquatic organisms are successfully reproducing, as demonstrated
by many young specimens. Freshwater mussels are the only T&E listed species; the
federally and state listed Appalachian elktoe is found upstream of the Mill, but not
downstream and is planned for reintroduction following successful survival and growth
of the state species of concern, the wavy -rayed lampmussell, in the thermally affected
reach. There are no critical function zones for aquatic life in the zone of initial mixing
other than a zone of passage, which has been demonstrated to occur through detailed
measurements and plume modeling. The thermal discharge and zone of initial mixing
cause minimal habitat exclusion in the warmest months in the 0.3 PRM between the
outfall and Fiberville Bridge. There are no unique or rare habitats affected by the heated
effluent. A habitat former, the hornleaf riverweed was not found at sampling stations in
the thermally affected reach but is also sporadic in reference areas; the macroinvertebrate
occupants of its habitat are nonetheless abundant in the thermally affected reach. Trends
in the aquatic community are toward progressive improvement since studies began in
1988. Nuisance species are not present or abundant when they occur. There are no
commercial fisheries in the Pigeon River, but the indigenous sports fish, smallmouth bass
and rock bass, have increased, especially relative to the non-native redbreast sunfish. The
magnitude and duration of any definable thermal effects (e.g., warm -water periphyton
and chiromomids in the mixing zone) are generally low and of short duration during the
warmest times of year. The high species diversity, abundance of aquatic organisms, lack
of abnormalities in fish, good relative weights of fish all indicate low sub -lethal or
indirect impacts. Detailed evaluation of other pollutants in the Pigeon River (including
H

permitted discharges) indicated a low likelihood that there would be detrimental
interaction with the added heat and warmer temperatures.
Reference area comparisons were favorable. Evaluation of the thermal and
biological data for nine thermally affected sites compared to six reference sites in the
Pigeon River watershed upstream of the Mill and the adjacent Swannanoa River showed
general and statistical similarity although there were some differences attributable to
historical pollution and geographic isolation that limits recolonization. Water
temperatures throughout the thermally affected reach were within the habitable zone for
aquatic life. The community in the zone of thermal mixing 0.3 PRM from the discharge
where temperatures were highest was the least similar to reference sites. Ongoing
reintroductions of fish and freshwater mussels are repopulating the thermally affected
reach with indigenous species. Other indigenous species (crayfish, salamanders) are
potential targets for additional reintroductions.
The trend of biological improvement of the thermally affected reach continued
from previous studies in 1988, 1995, 2000, and 2005. Species numbers of fish and
invertebrates have been increasing. The percentage of pollution intolerant species has
increased, such as the EPT group of macroinvertebrates and fish such as smallmouth bass
and rock bass, while relative numbers of pollution tolerant and non -indigenous species
has decreased, such as common carp and redbreast sunfish. Reintroductions of presumed
native species that have not recolonized on their own after years of absence have
generally been successful.
The detailed studies and analyses presented in this Demonstration support
the conclusion that the existing permit limitations on the thermal discharge are
appropriate for fostering a balanced and progressively improving biological
community in the Pigeon River. Therefore, Evergreen/Blue Ridge proposes the
alternative thermal limitation as written in the 2010 Permit, following revision by
the Settlement Agreement:
The Weekly Average instream temperature measured at a point 0.4 miles
downstream of the discharge location shall not exceed 32°C during the months
of July, August, and September and shall not exceed 29°C during the months of
October through June. The monthly average instream temperature measured
at this location shall not exceed the monthly average instream temperature of
the upstream monitoring location by more than 8.5°C.
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TABLE 4.1: Assessment summary, indicating whether the study data and
assessments support the conclusion that the thermal discharge, as currently
permitted and proposed for continuation, protects and propagates a balanced
indigenous community of shellfish (macroinvertebrates), fish and wildlife in the
Pigeon River. See text and Appendix B for details. NA=low abundance makes the
species a poor RIS.
Protection and Propagation of a Balanced Indigenous Community
Assessment Elements/ Fully Partially Does Not Comments
Indicators of Appreciable Supports Supports Support
Harm
RIS:
Rock bass X
Shiners (group) X
Redbreast sunfish X
Central stoneroller X
Smallmouth bass X
Northern hogsucker X
Black redhorse X
Darters (group) X
Common carp
River chub
Mottled sculpin
Banded sculpin
Trophic levels X
Diversity X
Sustainability X
Food -chain species X
Domination by tolerant sp. X
Indigenous species change X
T&E species (mussels)
Critical function zones X
Habitat exclusion
Unique habitat X
Habitat former
Nuisance species X
Zone of passage X
Fisheries change X
Wildlife
Magnitude & duration X
Sublethal/indirect effects X
Interaction with pollutants X
Reference area comparisons X
Trends in community X
Some thermal effect
Low abundance; NA
Low abundance; NA
All trophic levels present
X Mussels being reintroduced
X Minor near dischg in summer
X Sporadic distribution
Corbicula up, carp down
X Few crayfish & salamanders
Z •

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