NC0000272_Suggested Expansion of temperature sections of draft Fact Sheet_20220401

Suggested expansion of the temperature sections of the draft Fact Sheet for NPDES Permit NC0000272
based on comments received by NCDENR/NCDWR from EPA.
C. C. Coutant, draft January 17, 2021, modified January 28, 2021
[Pages are those for the June 14, 2019 draft Fact Sheet where temperature is mentioned.]
Page 3
Temperature
The facility first requested and received a 316 (a) variance (approved by EPA) for temperature on August
6, 1985. This determination demonstrated that the effluent limitations relating to the thermal component
of the Champion discharge were more stringent than necessary to assure protection and propagation of a
balanced indigenous population of shellfish, fish, and wildlife in the Pigeon River. The 316(a)
temperature variance was approved based on protection of the appropriate use classification of the Pigeon
River. Blue Ridge Paper and its antecedent operators submitted several Balanced and Indigenous Species
studies on the Pigeon River since then, in 1987, 1995, 2000, 2005, and 2012 pursuant to the monitoring
requirements of the preceding permits. The temperature variance was reviewed and renewed as part of the
Triennial Review in 1997. This sequence of studies demonstrated a trend toward progressive
improvement in river biology, especially after major mill modifications beginning in 1990.
The most recent study (2012), submitted in January 2014 was conducted by the University of Tennessee.
These studies included temperature monitoring and modeling of the Pigeon River from above the mill to
the headwaters of Waterville Reservoir. Biological studies included benthic organisms and fish, with
specific attention to decision criteria in the federal Clean Water Act Section 316(a) and EPA's
implementing regulations for ensuring a Balanced Indigenous Community in the water body. DWR
scientists have reviewed the report and concluded that continuance of the temperature variance is
appropriate. Therefore, the Division of Water Resources is recommending continuation of the temperature
variance with reporting requirements consistent with the previous permits.
During the last permit renewal, the variance requirements were changed and the temperature
difference between upstream and downstream monitoring locations (AT) was reduced from 13.9oC to
8.5oC despite the fact that BIP [balanced, indigenous population] study results were approved.
Page 10
[Note for review that the second paragraph elaborates on the zone of passage, which was EPA's
comment #1. This was also described in my letter of July 20, 2020 (see first request). Also, the
third paragraph notes the response to their comment #2.]
Rationale for Temperature Variance Renewal
Blue Ridge Paper submitted the latest Balanced and Indigenous Species Study on the Pigeon River in
2014 (for the study conducted in 2012). The study was conducted by the University of Tennessee and
evaluated temperature and biological conditions from upstream of the mill to the headwaters of
Waterville Reservoir (44 miles downstream of the mill). The study was designed to include components
of studies conducted in 1987, 1995, 2000 and 2005 in order to allow comparisons suitable for identifying
temporal trends in aquatic communities of fish and benthic organisms. The study gave specific attention
to decision criteria in the federal Clean Water Act Section 316(a) and EPA's implementing regulations for

ensuring a Balanced Indigenous Community in the water body. It followed the guidance of EPA's (with
the Nuclear Regulatory Commission) 1977 guidance manual for conducting thermal -discharge
assessments.
The 2012 study included detailed evaluation of Pigeon River temperatures at 20 stations during the
biological field study and two stations in a nearby, similar river as a reference (Swannanoa River). River
and mill -discharge temperature measurements and associated meteorological data were used to update
a one-dimensional computer model of Pigeon River temperatures. The model was then used to estimate
water temperatures under differing flow and environmental conditions. Detailed measurements in the
thermal -discharge plume in the river were used to parameterize a three-dimensional plume dispersion
model (EPA -supported CORMIX), which was applied at different river flows. Results of the one-
dimensional river model showed that the median modeled increase in weekly average temperature due
to the mill effluent is 3.1°C, 2.5°C and 1.1°C at 0.3, 4.2, and 20.6 miles downstream of the effluent,
respectively. The thermal plume model showed that during low Pigeon River flow rate, the thermal
plume mixed rapidly across the majority of the river width with a small zone of lower temperature ("'7°C
above ambient of 20.7°C) primarily along the east shoreline at the Fiberville Bridge (0.3 miles
downstream of the effluent) and the center channel of the river. Such temperatures are tolerated by
fish in the Pigeon River, especially for short exposures during passage. During medium to high flow
rates, the thermal plume had not mixed across the width of the river at the Fiberville Bridge leaving a
clear zone of passage at near ambient temperatures. The model results compared favorably with Google
Earth images of the river, which showed the plume as a band of darker colored water.
The biological study collected, identified, and enumerated fish and benthic species sampled at four
stations upstream of the mill (reference sites), 16 locations along 52.9 miles the Pigeon River
downstream of the thermal discharge, and at two reference locations in the nearby Swannanoa
River as additional reference sites. The analysis compared the biological communities at each
Pigeon River location to results in previous studies in 1987, 1995, 2000, 2005 to identify trends. Both
community -level indicators of potential harm and abundances and biological data for representative
species (RIS and other species of interest) were evaluated in accord with EPA's implementing regulations
and guidance. For fish, both community -level attributes and species' temperature requirements were
evaluated. For benthic invertebrates, community attributes were evaluated (taxa richness, EPT taxa
richness, North Carolina Biotic Index) because few species -specific thermal tolerance data are available.
EPT taxa (aquatic insect taxonomic Orders Ephemeroptera, Plecoptera, Trichoptera) are pollution
intolerant species used as indexes of water quality. The North Carolina Biotic Index is the NCDENR -
approved bioclassification method for North Carolina streams.
The key results of the study were:
• thermal exposures in the thermally -affected river were within the range suitable for biotic
community sustainability through cyclical seasonal changes;
• all normal trophic levels were represented;
• species diversity was comparable to reference locations (upstream and in the Swananoa R.);
• normal food -chain organisms (benthic invertebrates and small fish) were present;
• domination by pollution -tolerant species was not found;
• a temporal trend toward increase in indigenous species was found (e.g., rock bass abundance
increased relative to non -indigenous sunfish; decline of non-native and nuisance common carp);
• threatened or endangered species were evaluated, and a mussel species lost to the thermally
affected Pigeon River was found to be capable of survival and growth (transplanted);

• the one critical function zone found, a zone of passage around the thermal plume, maintained
cooler water at all river flow levels, although less at low flows;
• the only habitat exclusion would have been the warmest parts of the thermal plume (-200 m2, —1
minute drifting travel time) for short periods in summer;
• habitat formers were not disrupted, although an aquatic plant was reduced but not to exclusion of
macroinvertebrates that usually are found in its habitat;
• there was an increase from year to year of smallmouth bass, a valuable recreational species;
• sublethal or indirect effects were not evident from species numbers and abundances;
• evaluation of interactions of added heat with numerous other pollutants indicated that the most
likely interaction was with dissolved oxygen, which is controlled by other provisions of the
discharge permit;
• The biological community of the thermally affected river was similar to four reference areas
upstream of the mill and two in the similar Swannanoa River;
• overall, the added heat from the mill was concluded to have effects that were low in magnitude
and duration and not sufficient to endanger the protection and propagation of aquatic life in the
Pigeon River. Moreover, the trends in aquatic species and their abundances reflected the gradual
improvement in the riverine ecology since 1987 despite long-term addition of heat from the mill.
DWR biologists have reviewed the report and concluded that continuance of the temperature variance
is appropriate. Therefore, the Division of Water Resources is recommending continuation of the
temperature variance with reporting requirements consistent with the previous permits. The facility will
be required to provide a new Balanced and Indigenous Species Study prior to the permit renewal.