NC0000272_Analysis of Color Concentrations 4-26-2021_20220401

ANALYSIS OF COLOR CONCENTRATIONS IN THE PIGEON RIVER
April 26, 2021
AQUAETER, INC.
R&S 2591695_1

SECTION 1.0
INTRODUCTION
Blue Ridge Paper Products LLC, doing business as "Evergreen Packaging" (Evergreen),
operates the Canton pulp and paper mill ("Canton Mill") in Canton, North Carolina. Since 1988,
the Mill has reduced color loadings to the Pigeon River by more than 90%.
Since 2001 the Canton Mill has sampled and analyzed True and Apparent Color in the
Pigeon River upstream from the Mill's discharge and approximately 0.4-mile downstream at the
Fibreville Bridge.' In 2009, Evergreen retained AquAeTer to sample and analyze True and
Apparent Color in the Pigeon River and its tributaries. Based on the Mill's data, and the data
collected by AquAeTer, "A Comprehensive Assessment and Analysis of Color in the Pigeon
River2" was developed. In January 2018, AquAeTer issued a follow-up analysis on data collected
since 2009, "Analysis of Color Concentrations in the Pigeon Rivera." An update was prepared in
2019 to include data collected in 2018. This report updates the analysis to include data collected
in 2019 and 2020.
In addition to the data collected by the Mill, the Tennessee Department of Environment
and Conservation (TDEC) collects color data on the Pigeon River at the state line located at
Waterville, N.C4.
PURPOSE OF REPORT
This report supplements the Comprehensive Assessment and Analysis of Color in the
Pigeon River with an analysis of color concentrations in the Pigeon River upstream from the
Canton Mill at Park Street and downstream from the Mill's discharge at the Fibreville Bridges.
The report compares the color concentrations at Fibreville and the difference in concentration
1 NPDES Permit NC 0000272 issued to the Canton Mill by the North Carolina Department of Environmental
Quality requires the sampling. The Canton Mill also samples and analyzes color concentrations at Hepco
(approximately 20 river miles downstream) and at Brown's Bridge in Tennessee (approximately 38 miles
downstream), approximately'h mile downstream from the Duke Energy Progress Hydro -electric plant.
2 AquAeTer, Inc. (2014). Comprehensive Assessment and Analysis of Color in the Pigeon River. Brentwood:
AquAeTer, Inc.
3 AquAeTer, Inc. January 31, 2018. Analysis of Color Concentrations in the Pigeon River. Brentwood: AquAeTer,
Inc.
4 This dataset is not as extensive as the dataset collected by the Mill. No information is given in the TDEC database
as to what time the samples were collected or if the hydroelectric plant was generating power at the time of
collection.
5 The report will also reference color concentrations at the NC / Tennessee state line and at a similar stream from the
same Ecoregion.

between the upstream and downstream stations from July 2010 through December 2020. This is
the period that the current NPDES permit and associated effluent limits have been in effect.
CONCLUSIONS
The long-term daily average contribution from the Canton Mill to true color in the Pigeon
River since July 2010 is 20 true color units at flows greater than or equal to the annual 30Q2.6 The
long term daily average color concentration at the Fibreville Bridge at flows greater than or equal
to the annual 30Q2 is 36 true color units. The 90th percentile of the long term contribution of true
color to the Pigeon River from the Canton Mill does not exceed 43 true color units for any month
of the year at flows greater than or equal to the monthly 30Q2. 8The difference in the long-term
daily average color concentration at Park Street in Canton (13 true color units), upstream from the
Canton Mill discharge, and the long term daily average color concentration at the North
Carolina/Tennessee state line (16 true color units), is 3 true color units.9 This difference is minimal
and imperceptible to the human eye.
METHODOLOGY
AquAeTer has evaluated the color in the Pigeon River upstream from the Canton Mill
discharge and at the Fibreville Bridge. The dataset used for this analysis extends from July 1, 2010
through December 31, 20201°, unless otherwise noted. The color data were also evaluated in
conjunction with the flows in the River. In particular, monthly flows were evaluated so that distinct
hydrologic/meteorologic periods that are statistically equivalent, but occur with the varying
background natural color that occurs in the River over the course of the different seasons, would
be analyzed separately but equivalently.
6 Table 5, page 11
7 Table 3, page 9
8 Table 5, page 11
9 Table 4, page 10 and Table 6, page 12.
10 This is the period of the current NPDES Permit.

SECTION 2.0
ANALYSIS OF STREAM FLOWS
15A N.C.A.C. 2B.0206 (a) (5) specifies that aesthetic water quality standards will be met
at flows greater than or equal to the minimum average flow for a period of 30 consecutive days
that has an average recurrence of once in two years (30Q2).11 The actual period for the calculation
is not specified. Historically, the period used has been an annual number, so an annual 30Q2 has
been calculated for the analyses in this report. However, the annual 30Q2 event is not reflective
of the actual stream conditions through the year for this stream. The chance for the annual 30Q2
to occur in any given month for an equivalent 30-day period is much greater than a 2-year return
interval, which is not in keeping with the NC standard. The period that is presented in this report
is for a monthly basis, which more accurately reflects the hydrologic cycle over the course of the
year. A comparison of the monthly 30Q2's to the annual 30Q2 is presented in Figure 1.
Each of the monthly 30Q2 Table 1. 30Q2 Monthly and Yearly Flows and
flows plotted in Figure 1 is
statistically equivalent to the other
months meaning they have the
same statistical probability of
occurring. However, the annual
30Q2 is not statistically likely to
occur in four months, and
represents a greater than a two-
year return interval in the other
eight months. The actual
calculated flows are provided in
Table 1. This demonstrates that
while the annual 30Q2 may
statistically have a 50% chance of
occurring in any given year, the
actual chance of the annual 30Q2
Recurrence Intervals
PERIOD
30Q2
(cfs)
Chance of Annual Flow
Occurring
(1 in _ Yrs)
(%)
January
385
56.5
1.8
February
431
>90
<1.1
March
461
>91
<1.1
April
430
>91
<1.1
May
294
>90
<1.1
June
229
59.2
1.7
July
164
18.5
5.4
August
131
4.8
20.9
September
133
4.4
22.7
October
177
4.6
21.9
November
209
10.0
10.0
December
284
41.7
2.4
Annual
91.1
2
50
flow occurring 50% of the time will not occur in any given month.
The United States Environmental Protection Agency (USEPA) also recognizes that, in
some cases, streams need to and can be evaluated on a monthly basis 12 due to the variable
hydrologic conditions found. This analysis is and has been applied in many southern states as well
11 Color is an aesthetic pollutant.
12 US EPA. (1997). Technical Guidance Manual for Performing Wasteload Allocations, Book II.• Streams and
Rivers - Part 1: Biochemical Oxygen Demand/Dissolved Oxygen and Nutrients/Eutrophication. Washington, DC:
US EPA.

as in some northern states and was originally proposed by the old U.S. Public Health Service, or
pre-USEPA.13 15A NCAC 02B .0206 (a) states that water quality based effluent limitations shall
be developed to allow appropriate frequency and duration of deviations from the water quality
standards. The North Carolina statute is in line with the USEPA guidance. The monthly 30Q2
analyses represent a precise analysis of the same hydrologic event for each month of the year and
do not introduce bias in the analyses due to multiple months with different hydrologic and
meteorologic events not related to the same statistical event 30Q2 or 50% occurrence interval. In
other words, an annual calculation can be calculated but it has no chance to occur 50% of the time
in any given month.
Figure 1. Comparison of Annual and Monthly 30Q2 Low Flows
500
450
400
4 350
300 ♦
250
200
150
w 100
50
0
•
•
•
•
•
c,„
8 QJ U a)U
MONTH Z a.)
♦ Monthly 30Q2 Annual 30Q2
13 There are multiple NPDES Permits in the southeast which use monthly flow limits (DS Smith Riceboro on the
North Newport River and Georgia Pacific's Brunswick Mill on the Turtle River (Ga.)), (Georgia Pacific mill in
Naheola, Alabama on the Tombigbee River and West Rock Mill on the Tombigbee (Alabama)) and (Domtar Mill at
Ashdown, Arkansas).

SECTION 3.0
ANALYSIS OF COLOR CONCENTRATIONS
The Canton Mill has been collecting in -stream color data since 2001. AquAeTer collected
samples from 2009 through 2011 in the stream and in the tributaries. There are 1,915 days with
measurements collected at Fibreville since January 1, 2001. This report focuses on the period
beginning July 1, 2010, the effective date of the most recent NPDES Permit.14 This period includes
1,093 samples collected on the same day at Park Street and at Fibreville.
The analyses presented evaluate True Color in the River in various ways. The first is an
analysis of the samples collected at Fibreville. This location is approximately 0.4-mile
downstream from the Mill's outfall, and has been considered the compliance point or edge of
mixing zone.
The dataset for the period July 1, 2010 through December 31, 2020, as well as the entire
period of record was evaluated. The Comprehensive Assessment and Analysis of Color detailed
that concentration in the River is not related to flow, but the color loading or pounds per day can
be reasonably predicted based on the flow. The predicted mass loading can then be converted back
to a concentration in order to predict a concentration. However, the analysis in this report focuses
on measured concentration data.
EVALUATION OF DATA
Calculation of the Average (Mean)
The first evaluation is the proper identification of an average. The arithmetic mean is a
common way to calculate an average. An arithmetic mean is simply the sum of the individual
values divided by the number of values, or mathematically:
n
xi
x= —
1=i
n
1
The arithmetic mean is strongly influenced by both large and small values. When a dataset
is normally distributed, the arithmetic mean is appropriate. However, when a dataset is skewed,
14 This report presents an analysis of color concentrations for the period July 1, 2010 — December 31, 2020. The
specified term of the current NPDES Permit is July 1, 2010 - June 30, 2015. However, Evergreen timely submitted its
renewal application on December 31 2014. As such, the current permit is administratively continued pursuant to N.C.
Gen. Stats. 150B-3 pending final action by NCDEQ on the permit.

the arithmetic mean will no longer represent the central tendency of the dataset. Another average
is the median value.
A skewed dataset may follow a log -normal distribution. For these datasets, the mean and
median are calculated using the formulas:
Mean, Yin = exp
`i=1
C2 * +
n xi n (xi
exp Li=1 n vn
n ln(xi)
n
— x) — x)
n ) * exp (r=1(xi
n
1J\
2
Median, zln = exp
i=1
Calculation of the 90th Percentile
2
3
The second evaluation is to calculate the 90th percentile of the dataset. The 90th percentile
method is used and accepted by EPA to determine if a set of data for a pollutant parameter is
meeting a numerical water quality standard. The 90th percentile value is greater than 90% of the
distribution fit to the dataset. Conversely, 10% of the distribution fit to the dataset is equal to or
greater than the 90th percentile value. Since the percentile is based on the fit of the distribution, it
is possible to have more than 10% of the actual collected dataset that are greater than the 90th
percentile.
For a normally distributed dataset, the 90th percentile is calculated using the formula:
Normal 90th percentile, x90 = 43-1(0.9) * s + x = 1.282
i=1
(xi — x.)z
+x
n
4
Similarly, for a log -normally distributed dataset the 90th percentile is calculated using the
formula:
Log — normal 90th percentile, x90,17, 5
ln(xi))a
n
= exp
n On (xi) — Ln 1
1.282 *
1 i=1 i=1

Determination of Dataset Distribution
The evaluation of the full dataset that extends from January 1, 2001 to the present indicates
that most months follow a log -normal distribution. The goodness of fit results using the Anderson -
Darling (A-D) test for both normal and log -normal distributions for the full dataset and the most
recent dataset are presented in Table 2. When the result presented in the table is greater than 0.05,
relating to a 95% probability, the dataset fit the specified distribution. The best fit distribution for
each case is highlighted yellow in Table 2. The appropriate calculations will be used for
calculating the monthly averages. The datasets that do not pass the 0.05 probability will still be
treated as log normal.
Table 2. Goodness of Fit for a 95% Probability for Dataset at Fibreville
MONTH
Normal Distribution
Log -Normal Distribution
Full Dataset
July 1, 2010 -
Present
Full Dataset
July 1, 2010 -
Present
January
0.00
0.00
0.78
0.74
February
0.00
0.00
0.60
0.61
March
0.00
0.00
0.20
0.21
April
0.00
0.00
0.07
0.00*
May
0.00
0.00
0.03*
0.24
June
0.00
0.00
0.09
0.49
July
0.00
0.36
0.81
0.09
August
0.00
0.00
0.23
0.63
September
0.00
0.00
0.01*
0.03*
October
0.00
0.00
0.35
0.09
November
0.00
0.00
0.00*
0.00*
December
0.00
0.00
0.06
0.05
Annual
0.00
0.00
0.00*
0.00* I
Note:
* = Value does not pass A-D test, but this distribution was used.
EVALUATION OF IN -STREAM COLOR AVERAGES
Long-term Daily Average for each Month for In -Stream Color Concentrations Measured at
Fibreville
The long-term average of the daily concentration values for each month for the period from
July 1, 2010 through December 31, 2020 is presented in Table 3. This table demonstrates that the
color concentration measurements at Fibreville are less than or equal to 40 color units on a long-
term average for each month when flows are greater than or equal to the monthly 30Q2. The 90th
percentile column is presented since that method is used and accepted by the USEPA to determine
if a set of data for a pollutant parameter is meeting a numerical water quality standard. The table
shows that one month is as high as 57 color units at the 90th percentile, while nine of the remaining

months are less than 50 color units. Though there is no North Carolina numerical water quality
standard for color, discussions of acceptable target values for the Pigeon River in the range of 50
to 100 have been considered in the past. All of the values in Table 3 fall within or below this range.
Table 3. Long-term Daily Average Color Concentration for each Month for In -Stream
Measurements at Fibreville for July 1, 2010 through December 31, 2020
MONTH
DISTRI-
BUTION
TOTAL
NUMBER OF
VALUES
LONG-TERM
DAILY AVG.
WHEN FLOWS
>=A30Q2
(mg/L)
LONG-TERM
DAILY AVG.
WHEN FLOWS
>=M30Q2
(mg/L)
LONG-TERM
90t' PER -
CENTILE
WHEN FLOWS
>=M30Q2
(mg/L)
Jan.
LN
90
26
18
30
Feb.
LN
81
24
18
29
Mar.
LN
89
24
18
25
Apr.
LN
86
21
18
25
May
LN
90
24
21
30
Jun.
LN
77
37
24
34
Jul.
N
97
47
35
51
Aug.
LN
99
46
39
57
Sep.
LN
94
49
37
56
Oct.
LN
98
42
33
49
Nov.
N
95
43
29
45
Dec.
LN
97
32
23
35
Annual
LN
1,093
34
26
43
Note:
LN = Log Normal
A30Q2 = Annual 30Q2 Condition
M30Q2 = Monthly 30Q2 Condition
The values in Table 3 do not represent a separation of background color and color
contributed by the Mill. The long-term daily average Park Street measurements for each month
are presented in Table 4.

Table 4. Long -Term Daily Average Color Concentration at Park Street Upstream for
July 1, 2010 through December 31, 2020
MONTH
DISTRI-
BUTION
TOTAL
NUMBER OF
VALUES
LONG-TERM
DAILY AVG.
WHEN FLOWS
>=A30Q2
(mg/L)
LONG-TERM
DAILY AVG.
WHEN FLOWS
>=M30Q2
(mg/L)
LONG-TERM
90th PER -
CENTILE
WHEN FLOWS
>=M30Q2
(mg/L)
Jan.
LN
90
10
11
19
Feb.
LN
81
11
13
24
Mar.
LN
89
10
12
20
Apr.
LN
86
11
13
23
May
LN
90
12
12
20
Jun.
LN
77
14
12
21
Jul.
LN
97
15
15
24
Aug.
LN
99
15
15
24
Sep.
LN
94
17
18
26
Oct.
LN
98
18
20
32
Nov.
LN
95
16
17
26
Dec.
LN
97
14
15
25
Annual
LN
1,093
13
14
25
Note:
LN = Log Normal
A30Q2 = Annual 30Q2 Condition
M30Q2 = Monthly 30Q2 Condition
The variable nature of color in the Pigeon River upstream from the Mill is presented in
Table 4. In some months the expected long-term daily average when flows are greater than or
equal to the Monthly 30Q2 are as high as 18 color units. The 90th percentile values in some months
are as high as 32 color units. Background concentrations have been measured as high as 94 mg/L
in the Pigeon River upstream from the Mi11.15 This means that any instantaneous numerical water
quality target value must account for the background at the time of the sample.
Determination of In -Stream Color Delta at Fibreville
The Pigeon River coming to the Mill in Canton has been measured for color on a routine
basis. Because of the variability in background color as shown in Table 4, an in -stream delta
between the background and the downstream location is more appropriate to evaluate the Mill's
contribution to color in the River. Similarly to the in -stream values, the majority of the long-term
daily average delta concentrations for each month do not fit a normal distribution. The long-term
daily average in -stream delta concentrations for each month are provided in Table 5.
This table demonstrates that for any month, the long term daily average contribution of the
Canton Mill to color at Fibreville when flows are greater than or equal to monthly 30Q2 is 24 true
15 December 24, 2015 at Park Street Bridge in Canton

color units or less. The 90th percentile of color contribution of the Canton Mill does not exceed 41
true color units for any month when flows are greater than or equal to the monthly 30Q2.
Table 5. Long -Term Daily Average In -Stream Delta Color Concentration at Fibreville
Bridge downstream for Each Month for July 1, 2010 through December 31, 2018
MONTH
DISTRI-
BUTION
TOTAL
NUMBER OF
VALUES
LONG-TERM
DAILY AVG.
WHEN FLOWS
>=A30Q2
(mg/L)
LONG-TERM
DAILY AVG.
WHEN FLOWS
>=M30Q2
(mg/L)
LONG-TERM
90t' PER -
CENTILE
WHEN FLOWS
>=M30Q2
(mg/L)
Jan.
LN
89
16
7
15
Feb.
LN
77
13
5
13
Mar.
LN
88
14
6
11
Apr.
LN
82
10
5
10
May
LN
87
12
9
18
Jun.
LN
77
22
12
21
Jul.
LN
97
32
21
36
Aug.
LN
99
32
24
41
Sep.
LN
92
32
19
37
Oct.
LN
97
24
13
26
Nov.
LN
95
27
12
24
Dec.
LN
95
19
10
29
Annual
LN
1,093
20
12
26
Note:
LN = Log Normal
A30Q2 = Annual 30Q2 Condition
M30Q2 = Monthly 30Q2 Condition
Determination of Average Color on the French Broad River and Comparison to the Pigeon
River at or near the North Carolina — Tennessee state line
For comparison purposes, the color measurements collected on the French Broad River
upstream from Newport, Tennessee are also included in Table 6. It is noted that the difference
between the upstream and downstream locations on the French Broad River is greater than the
Pigeon River for the same time period. It is noted that the dataset for the Pigeon River is much
more extensive, meaning that the conditions monitored are more likely representative of conditions
present at any given time. Both Rivers follow the general expectation that color increases in the
downstream direction as stream order increases.
The Tennessee Department of Environment and Conservation collects samples on the
Pigeon River near the state line, as well as, on the French Broad River at the Highway 70 Bridge
(near Del Rio, TN) and at the Highway 321 Bridge (near Newport, TN). There are not enough
data points to calculate long-term daily averages for each month, nor to determine the proper

distribution of the datasets. Averages of the three datasets are presented, along with the number
of samples in each calculation.
There are two things to note when evaluating the comparison between the upstream station
and the station at the state line. First, the measurements collected at Park Street are collected by
the Canton Mill, while the measurements collected at the state line are collected by TDEC. The
second thing is that within the time frame analyzed, the Canton Mill has collected 1,093
measurements, while TDEC has collected 373 measurements. The difference in the number of
samples collected means that the Canton Mill's dataset represents a more varied dataset in terms
of the environmental conditions present, such as low -flow, rain events, ice cover, etc. It is noted
that TDEC deliberately does not sample when natural flow conditions are elevated and thus does
not sample the full range of hydrologic and meteorologic periods during the year. The TDEC SOP
for not sampling during elevated flow conditions is based on safety, although the sampling station
utilized by TDEC at the State Line is dangerous regardless of the flow in the River.
The Pigeon River near the state line and the French Broad River near Del Rio are especially
suited for comparison purposes since 1) they both drain the identical ecosystem classification; 2)
they are both level 5 on the Schuler stream classification system (stream order); and 3) the French
Broad near Del Rio has no known large sources of color discharging to it. The comparison shows
that the Pigeon River near the state line actually has less color than the French Broad River near
Del Rio when compared to an equivalent stream system (i.e., same ecosystem and same order
stream). This indicates the Pigeon River at the state line does not have color levels outside of the
expected range for a stream with no large point source of color discharging to it. These data also
show the difference in color at the Park Street Bridge on the Pigeon River and the color at the state
line on the Pigeon River is only 3 color units which is imperceptible by the human eye.

Table 6. Comparison of Color Concentration for In -Stream Measurements on Pigeon
and French Broad Rivers (Post July 1, 2010
PARAMETER
PIGEON RIVER
AT PARK
STREET IN
CANTON
PIGEON RIVER
NEAR NC/TN
STATE LINE"
FRENCH
BROAD RIVER
NEAR DEL RIO,
TN
FRENCH
BROAD RIVER
NEAR
NEWPORT, TN
Drainage Area (sq.
mi.)
130
538
1,713
1,858
Number of Samples
1,093
295
30
24
Samples Collected
by
EPI
TDEC
TDEC
TDEC
Average Color,
mg/L
13
16
19
24
Minimum Color,
mg/L
1
ND
3
3
Maximum Color,
mg/L
94
43*
63
110
Note: Both French Broad TDEC stations are upstream from the confluence of the Pigeon
River and the French Broad River near Newport, Tennessee.
'l': Samples reported on TDEC's website for PIGEO024.7CO. The US Water Quality
Data Portal reports 373 samples from the same location collected for Station
TDECWR_WQX-TNW000004788. There are 287 results collected on the same day.
Of those, 190 samples reported different results. For the purposes of this report, the
values reported on TDEC's website are used.
*: A sample of 95 was measured in 2008 by TDEC at this location.

SECTION 4.0
FINDINGS AND CONCLUSIONS
FINDINGS FOR THE PERIOD JULY 1, 2010 THRU DECEMBER 31, 2020:
Based on a methodology used by and recognized by EPA, 30Q2 values for each month of the year
for the Pigeon River more accurately reflect the hydrologic cycle over the course of the year.
Although an annual 30Q2 flow can be calculated, the annual event has no chance of occurring in
any given month of the year for 50% of the time.
Color concentration measurements at Fibreville are less than or equal to 39 color units on a long-
term average for each month when flows are greater than or equal to the monthly 30Q2.
The 90th percentile of the long-term daily color concentrations at Fibreville when flows are equal
to or greater than the monthly 30Q2, ranged from 25 in March to 57 in August. (90th percentile
was examined from EPA's guidance on comparing a set of data to a specific water quality standard
i.e. if the 90th percentile is less than a target value, then water quality standards are being met).
The color concentration at Fibreville is indicative of both the background and the Mill.
The long term daily average color concentration added, i.e., the delta, to the Pigeon River by the
Mill, at flows greater than or equal to the monthly 30Q2, is less than or equal to 25 color units for
any month. The 90th percentile of the color concentration added by the Mill, at flows greater than
or equal to the monthly 30Q2, is less than or equal to 41 color units for all months.
The color concentrations in the Pigeon River upstream from the Mill are variable. In some months
the expected long term daily average color concentration, when flows are greater than or equal to
the monthly 30Q2, are as high as 20 color units; and 90th percentile values in some months are as
high as 32 color units. Also, color concentrations upstream from the Mill have been measured as
high as 94 color units. This means that any instantaneous numerical water quality target value
must account for the background at the time of the sample.
OTHER FINDINGS:
Comparison of the French Broad River near Del Rio shows the Pigeon River at the Stateline does
not have color levels outside of the expected range for a stream with no large point source of color
discharging to it.
The difference in the long-term daily average color concentration at Park Street in Canton,
upstream from the Canton Mill discharge, and the long-term daily average color concentration at
the North Carolina -Tennessee Stateline is 3 true color units.

CONCLUSIONS:
The long term daily average contribution (delta) of the Canton Mill to true color in the Pigeon
River is 20 color units at flows greater than or equal to the annual 30Q2. The long term daily
average color concentration at the Fibreville Bridge at flows greater than or equal to the annual 30
Q2 is 34 true color units. The 90th percentile of the long-term contribution of true color to the
Pigeon River from the Canton Mill does not exceed 41 true color units for any month of the year
at flows greater than or equal to the monthly 30Q2. The difference in the long term daily average
color concentration at Park Street in Canton (13 true color units), upstream from the Canton Mill
discharge and the long term daily average color concentration at the North Carolina -Tennessee
state line (16 true color units) is 3 true color units. This difference is minimal and imperceptible
to the human eye.
Though there is no North Carolina numerical water quality standard for color, discussions of
acceptable target values for the Pigeon River in the range of 50 to 100 have been considered in the
past. The long-term average and 90th percentile values at Fibreville and the long-term average and
90th percentile contributed by the Mill meet this target range.