NC0000272_Responses to Info Request from EPA_20220401

Charles C. Coutant, Ph. D. 120 Miramar Circle
Aquatic Ecologist
July 20, 2020
Oak Ridge, TN 37830-8220
865-483-5976
e-mail: [e-mail]
Responses to information requests from EPA Region 4 to NCDENR (June 22, 2020)
regarding the report "Canton Mill Balanced and Indigenous Species Study for the
Pigeon River" submitted to NCDENR on January 2014 by Blue Ridge Paper
Products, Inc. dba Evergreen Packaging , Canton Office
In the following, the EPA Region 4 request is given first (italics), Mr. Chernikov's
(NCDENR) summation of phone discussions with EPA Region 4 staff (italics in yellow
highlight), and then my answer.
As in my responses to previous questions (February 13, 2020), I realize it is often difficult
to find the relevant text, tables and figures for every issue in a large document. I hope
these answers are helpful. Revision of the present document isn't really an option, but the
EPA requests will be helpful in preparing the study plan and report for any subsequent
variance requests.
-include a diagram depicting the thermal plume under the worst case scenario and address
the presence or absence of a zone of passage for which fish can travel around the thermal
plume — They want to know where exactly the stream meets the temperature standards.
The context of the information request is the thermal plume and zone of passage. The
current NC temperature standard for Class C surface waters in the mountain province is
"not to exceed" 2.8 degrees C (5.04 degrees F) above natural temperature (accessed from
epa.gov on June 23, 2020). A §316(a) demonstration such as the January 2014 report
under review is to support an effluent limitation as an alternative to the thermal standard,
which is considered more stringent than necessary for the protection and propagation of a
BIC. As the Fourth Circuit Court concluded in Appalachian Power Co. v. Train (1976),
compliance with existing water quality standards did not automatically satisfy the
requirement of §316(a). The CWA §316(a) requires consideration of site -specific criteria,
while water quality standards are applicable to relatively large segments of water bodies.
Thus, provision of a zone of passage was evaluated in terms of site -specific temperatures,
the measured complexity of the thermal discharge mixing, fish temperature requirements,
and likely fish exposures and their duration.
The demonstration document in Appendix A, Figure 88 shows actual measurements (not
model results) of cross sections of the river at two locations, the railroad bridge 170
meters downstream of the outfall and the Fibreville Bridge 570 meters downstream of the
outfall. The ambient temperature was 20.6 C and the river flow 2.63 m3/s, each close to
worst -case conditions in August. In each cross section (top two panels), there is cool
water along the east side of the river (refer to map on page 24 of main text). The mixing
thermal plume is complex at each set of detailed measurements (Figures 87 and 88 on
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Appendix A pages 92 and 93, respectively) and no exact boundary of the thermal plume
is definable. Even so, the east side retains water closer in temperature to the river
upstream.
The color coding in Figure 88 shows the temperature rise there to be about 6.8 C above
ambient (Delta T) or 27.4 C (influenced by natural shoreline warming and mixing of the
mill's thermal plume). As discussed in the RIS species descriptions, this is within the
thermal tolerance range of the warm -water fish assemblage. The third panel is a plan view
that shows Delta Ts in the vicinity of the thermal plume between the outfall and the
Fibreville Bridge. For aquatic life drifting downstream or swimming upstream, the peak
exposure temperatures in the zone of passage would last 1-2 minutes, well within the
thermal shock tolerance of temperature and duration of exposure. The thermal plume
under more typical river flows as a general reference for the plume geometry is seen in an
aerial photo in Appendix A, Figure 85.
-provide information of which fish collected are either heat -sensitive or nuisance species — They
want this information added to the Tables of species listed.
Lack of domination by pollution -tolerant species (as defined by the NC DENR) is discussed in
the Executive Summary of Appendix B (pages 5, 6) and Section 3.2.5 (page 57) of the main text.
Thermally tolerant fish species were rare (e.g., goldfish) with the exception of the abundant
redbreast sunfish, which is declining in relative abundance. Nuisance species are discussed in
Section 3.2.12 (page 59) of the main text where blue-green algae (cyanobacteria) are not
abundant in the Pigeon River downstream of the mill, Asiatic clams that some consider a
nuisance have expanded their range to the mill but are no more abundant than other similar
rivers, and the common carp is declining in abundance.
Appendix B, Table 3.2.1-1 (pages 49 & 50) lists the fish species collected from the Pigeon River
and four tributaries in 2012, and footnotes Intolerant and Tolerant species (species not footnoted
were intermediate). There were eight pollution intolerant species, four tolerant species, and 29
intermediate species. In addition, the RIS species -specific summaries highlight the non -
domination by pollution -tolerant species (summarized on page 82) and the two thermally tolerant
and less favored species (common carp and redbreast sunfish). As the EPA Environmental
Review Board opined in their 2006 review of the Brayton Point case, trends are important. The
nuisance common carp is decreasing in abundance across the sample years from 1995 to 2012.
The redbreast sunfish (non-native sportsfish) is declining in relation to its preferred competitor,
rock bass; neither is considered a nuisance.
Key attributes, including number of intolerant species, percentage of tolerant species, and
associated TVA IBI scores, at fish sampling stations are provided in Appendix B Table 3.2.3-1
(page 65). The table includes reference and thermally affected sites. The number of intolerant
species ranged from 1 to 3 in both six reference and ten thermally affected sites (those from the
mill to Waterville Reservoir). Percent tolerant species ranged from 0 to 0.8 in reference sites and
0 to 2.6 in the thermally affected sites. High percentages were localized at three stations (two
more than 10 miles downstream of the mill) suggesting causes other than the delta temperatures
from the mill, which were 2 C or less (Appendix B, Figure 83, page 88).
-provide a list of any receiving water body species that are endangered or threaten in
accordance with federal and state regulations — They want this information added to the
Tables of species listed.
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Threatened and endangered species are identified and discussed in Section 3.2.7 (page 58)
of the main text. There are no fish so listed. Two species of mussel in the Pigeon River
basin are listed, the Appalachian elktoe (Alasmidonta raveneliana; federal and state
endangered) and the wavy -rayed lampmussel (Lampsilis fasciola; state species of
concern). The Appalachian elktoe was found in the watershed upstream of the mill but
not elsewhere in the basin. The wavy -rayed lampmussel is being re -introduced to the river
downstream of the mill. Since these species were not found in sampling (and thus not on
the list of benthic species), they were given special treatment in the report (Appendix B,
Section 3.3.1, pages 77-79.
-analyze and present data to clearly demonstrate that affected communities have not shifted
to primarily heat tolerant assemblages — They want to know what segment of the river was
evaluated for BIP. Was it the segment from the facility to the lake or a shorter segment.
The biothermal assessment included the river from upstream of the mill (five reference
stations up to West Fork Pigeon River mile 6.6), in the thermal plume zone near PRM 63,
to near the confluence with the French Broad River (PRM 10.3) although the 17.7-mile
river reach from the mill to Waterville Reservoir was the thermally affected target of data
collection and analysis.
-analyze and present all data 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 — They
would like more details about reference streams.
In accord with the EPA Environmental Review Board's opinion on the Brayton Point
case, multiple reference sites (7) were selected for the Canton Mill bio-thermal analysis.
Five were in the same watershed upstream of the mill (three in the Pigeon River and one
each in the East and West Forks of Pigeon River; see map on page 24 of the main text),
while two were in an adjoining watershed, the Swannanoa River (see Section 1.5.2.1,
page 34). Tributaries to the Pigeon River downstream of the mill (Richland Creek,
Crabtree Creek, and Jonathan Creek) also provided reference data for waters not
thermally affected but adjacent to the thermally affected river (see map). Table 2.1 of
Appendix B shows the history of biological sampling stations between 1995 and 2012,
including all reference stations (important for determining trends). As is now well
understood, no two locations will yield identical biological communities. Nonetheless,
the multiple reference areas allow a broad picture of what biological community would be
expected for small rivers in the mountain province of North Carolina without the thermal
discharge. Multiple reference stations also provide data for detailed comparisons between
the thermally affected zones and the range of variability among unheated sites.
Temperatures were monitored in ten reference areas: two above the mill, one each in six
tributaries and two in the Swannanoa River (Section 2.2.1, page 41 of the main text; page
7 of Appendix A). The upstream and tributary reference areas provided data for
preparation of the one-dimensional thermal model of the Pigeon River. The Swannanoa
River temperature -monitoring stations provided data to evaluate their suitability as
reference areas for the Pigeon River.
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Key features of the benthic invertebrate data for comparing reference locations to the
thermally affected zone of the river are summarized in Table 3.1.1-2 of Appendix B. The
ratio of EPT taxa to the total taxa was generally less in the thermally affected area (0.25
to 0.48) than in the reference areas (0.23 to 0.58) but the ratios have been improving over
the years of sampling.
Fish collections for comparing reference and thermally affected areas are provided in
three tables: in the mainstem river in Appendix B tables 3.2.1-2 (upstream references and
thermally affected), 3.2.1-3 (tributaries) and 3.2.1-4 (Swannanoa sites). Key attributes of
the fish collections for reference and thermally affected zones are provided in Appendix
B Table 3.2.3-1 (page 65) (number of native fish species, darters, sunfishes, suckers and
intolerant species; % tolerant species, % omnivores, % specialized insectivores, %
piscivores, catch rate, % hybrids, % diseased, and IBI score). Comparisons of IBI scores
between 1995 and 2012 among reference and thermally affected stations are shown in
Appendix B, Table 3.2.3-2 (page 67). Fish community indices (richness, diversity, and
evenness) are compared in Appendix B Table 3.2.6-1 (page 76) for reference and
thermally affected locations for the 2012 and 2005 sampling seasons. There was a sharp
drop in the indices at the discharge, but improving (but variable) as one moved
downstream.
-include recent data or information on benthic macroinvertebrates — They believe that
macroinvertebrate data is integral to BIP determination
Benthic invertebrates are one of the biotic categories included in the report, as itemized on page
50 of the main report. Data on the benthic macroinvertebrates sampled in the Pigeon River, its
tributaries and two out -of -basin reference sites are presented in detail in Appendix B, Section
3.1. Taxa, taxa richness, EPT indices, NC BI scores, and historical comparisons among 1995,
2000, 2005, and 2012 are presented. In addition, specific attention was given in the main text
(Section 3.4) to mussel species and crayfish. The evidence supported the conclusion that there as
a trend of improvement from that observed in previous sampling. The main text does not,
however, summarize the benthic invertebrates as much as it does fish, other than referring to
Appendix B in section 3.2.4 (Food Chain Species Presence; page 56).
-include a thermal modeling study based on historical effluent temperatures and operating
conditions to determine appropriate permit limits for temperature — They commented that
recent model was based on the aerial photographs during high flow condition. They would
like more modeling information on the low flow condition.
Neither the 1-D longitudinal thermal model nor the thermal plume model was based
largely on aerial photographs, although some aerial photos were paired with physical
measurements and model results for context (Appendix A, figures 84-86, pages 89-91).
As described on page 32 of Appendix A, aerial imagery was used to accurately determine
the river width at different flows as required by the thermal plume model. The model
results were also compared to the image of the plume on the aerial photos as a
verification as described on page 34 of Appendix A (assisted by color differences
between the thermal discharge and the ambient river water).
Neither model was based solely on high -flow conditions. As detailed in Appendix A, the
longitudinal 1-D model was calibrated using approximately four months of measured
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river temperature data: two months of thermograph data collected in the summer of 2012
and two months in the winter of 2013. Winter and summer conditions are necessary
because environmental variables included in the model vary greatly between the warm,
humid summer and the cool, dryer winter. It was validated against daily temperature
measurements of the Pigeon River collected by the mill personnel from 2005 to 2013,
which included all flows during that time span.
The thermal plume model was based on the standard, EPA -approved model CORMIX
and cross -sectional temperatures measured at two distances from the outfall on August 12
and 29, 2012 (data plots are shown in Appendix A, figures 87 and 88, on pages 92 and 93
respectively). The CORMIX model was run at five different river flow rates (2.18, 2.63,
3.48, 11.86, and 16.54 m3/s; Appendix A, Table 13 on page 33) and the results were
summarized on page 3 of the main text. As typically happens, the years of a thermal -
discharge study don't occur when the lowest flows occur. The lowest flow modeled (2.18
m3/s) was considered "a very low flow day 6/17/2008" (page 35). For comparison, the
lowest flow recorded at Canton between 2000 and 2020 was about 1 m3/s in 2008
whereas the more typical lowest flows (9 of 20) were about 1.3 m3/s (USGS station
03456991 at https://nwis.waterdata.usgs.gov/usa/nwis accessed 6/24/20). Although the
lowest flow modeled wasn't the worst case, the river's biota sampled in 2012 reflected
any detrimental effects of plume temperatures occurring in that previous exposure.
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