2001 Roanoke Appendix II

Appendices
Appendix II
Biological Water Quality Data
Collected by DWQ
Benthic Macroinvertebrate Collections
Fish Community Collections
Fish Tissue Assessments
Lakes Assessments
A-II-1
Benthic Macroinvertebrate Sampling Methodology and Bioclassification Criteria
Benthic macroinvertebrates can be collected using two sampling procedures. DWQ’s standard
qualitative sampling procedure includes 10 composite samples: two kick-net samples, three
bank sweeps, two rock or log washes, one sand sample, one leafpack sample, and visual
collections from large rocks and logs. The purpose of these collections is to inventory the
aquatic fauna and produce an indication of relative abundance for each taxon. Organisms are
classified as Rare (1-2 specimens), Common (3-9 specimens) or Abundant (≥10 specimens).
Several data analysis summaries (metrics) can be produced from standard qualitative samples to
detect water quality problems. These metrics are based on the idea that unimpaired streams and
rivers have many invertebrate taxa and are dominated by intolerant species. Conversely,
polluted streams have fewer numbers of invertebrate taxa and are dominated by tolerant species.
The diversity of the invertebrate fauna is evaluated using taxa richness counts; the tolerance of
the stream community is evaluated using a biotic index.
EPT taxa richness (EPT S) is used with DWQ criteria to assign water quality ratings
(bioclassifications). "EPT" is an abbreviation for Ephemeroptera + Plecoptera + Trichoptera,
insect groups that are generally intolerant of many kinds of pollution. Higher EPT taxa richness
values usually indicate better water quality. Water quality ratings are also based on the relative
tolerance of the macroinvertebrate community as summarized by the North Carolina Biotic Index
(NCBI). Both tolerance values for individual species and the final biotic index values have a
range of 0-10, with higher numbers indicating more tolerant species or more polluted conditions.
Water quality ratings assigned with the biotic index numbers are combined with EPT taxa
richness ratings to produce a final bioclassification, using criteria for mountain/piedmont/coastal
plain streams. EPT abundance (EPT N) and total taxa richness calculations also are used to help
examine between-site differences in water quality. If the EPT taxa richness rating and the biotic
index differ by one bioclassification, the EPT abundance value is used to determine the final site
rating.
Benthic macroinvertebrates can also be collected using the DWQ’s EPT sampling procedure.
Four composite samples are taken at each site instead of the 10 taken for the qualitative sample:
1 kick, 1 sweep, 1 leafpack and visual collections. Only intolerant EPT groups are collected and
identified, and only EPT criteria are used to assign a bioclassification.
The expected EPT taxa richness values are lower in small high quality mountain streams, <4
meters in width or with a drainage area <3.5 square miles. For these small mountain streams, an
adjustment to the EPT taxa richness values is made prior to applying taxa richness criteria. Both
EPT taxa richness and biotic index values also can be affected by seasonal changes. DWQ
criteria for assigning bioclassification are based on summer sampling (June-September). For
samples collected in other seasons, EPT taxa richness can be adjusted. The biotic index values
can also be seasonally adjusted for samples collected outside the summer season.
Criteria have been developed to assign bioclassifications ranging from Poor to Excellent to each
benthic sample. These bioclassifications primarily reflect the influence of chemical pollutants.
The major physical pollutant, sediment, is not assessed as well by a taxa richness analysis.
A-II-2
Swamp Streams
Extensive evaluation, conducted by DWQ, of swamp streams across eastern North Carolina
suggests that different criteria should be used to assess the condition of water quality in these
systems. Swamp streams are characterized by slower flow, lower dissolved oxygen, lower pH,
and sometimes very complex braided channels and dark-colored water. DWQ has developed
draft biological criteria that may be used in the future to assign bioclassifications to these
streams. However, validation of the swamp criteria will require collecting data for several years
from swamp stream reference sites. The criteria will remain in draft form until DWQ is better
able to evaluate such things as: year-to-year variation at reference swamp sites, effects of flow
interruption, variation among reference swamp sites, and the effect of small changes in pH on the
benthos community. Other factors, such as whether the habitat evaluation can be improved and
the role fisheries data should play in the evaluation, must also be resolved. While it may be
difficult to assign use support ratings to these swamp streams, these data can be used to evaluate
changes in a particular stream between dates or to evaluate effects of different land uses on water
quality within a relatively uniform ecoregion.
Draft swamp stream rating criteria evaluate swamp streams based on benthic macroinvertebrate
data (collected in winter), fish community data and a habitat score. Benthic data collected
outside of the winter high flow period are not used to assign ratings. At least two of the above
referenced data types must be collected in order to assign a rating. Each of these data types is
assigned a point value of 10 (Good), 5 (Fair) or 1 (Poor), and the points are averaged to assign an
overall site rating (OSR): Good-Excellent (>7.5), Fair-Good (5.0-7.5), Fair (2.0-4.9) and Poor
(<2.0). Ratings for the benthic macroinvertebrate communities are based entirely on the biotic
index value: Good <6.99, Fair 7.75-7.00, Poor >7.75. Deep (nonwadeable) coastal rivers with
little or no visible current have different EPT criteria that are being used on a provisional basis
until more data can be gathered.
Flow Measurement
Changes in the benthic macroinvertebrate community are often used to help assess between-year
changes in water quality. However, some between-year changes in the macroinvertebrate
community may be due largely to changes in flow. High flow years magnify the potential effects
of nonpoint source runoff, leading to scour, substrate instability and reduced periphyton. Low
flow years may accentuate the effects of point source dischargers by providing less dilution of
wastes.
For these reasons, all between-year changes in the biological communities are considered in light
of flow conditions (high, low or normal) for one month prior to the sampling date. Daily flow
information is obtained from the closest available USGS monitoring site and compared to the
long-term mean flows. High flow is defined as a mean flow >140% of the long-term mean for
that time period, usually July or August. Low flow is defined as a mean flow <60% of the long-
term mean, while normal flow is 60-140% of the mean. While broad scale regional patterns are
often observed, there may be large geographical variation within the state and large variation
within a single summer period.
A-II-3
Habitat Evaluation
DWQ has developed a habitat assessment form to better evaluate the physical habitat of a stream.
The habitat score has a potential range of 1-100, based on evaluation of channel modification,
amount of instream habitat, type of bottom substrate, pool variety, bank stability, light
penetration and riparian zone width. Higher numbers suggest better habitat quality, but no
criteria have been developed for assigning ratings indicating Excellent, Good, Fair or Poor
habitat.
A-II-4
Table A-II-1 Benthic Macroinvertebrate Data Collected in the Roanoke River Basin, 1983 -
1999 (Current basinwide monitoring sites have the map number bolded.)
Subbasin/
Stream Location County
Site
No.
Index
No. Date
S/
EPT S
NCBI/
EPT BI
Bio
Class1
03-02-01
Dan R NC 704 Stokes B-1 22-(1) 08/99 85/41 4.19/3.30 G
08/94 57/28 3.84/3.51 G
07/90 94/48 4.48/3.68 E
07/88 89/38 4.06/2.98 G
07/86 84/37 4.00/3.17 G
08/84 86/36 4.66/3.58 G
Dan RSR 1695 Stokes B-2 22-8 08/99 72/37 4.57/3.95 G
08/94 45/20 4.75/3.87 G -F
North Double Cr SR 1504 Stokes B-3 22-10 08/99 -/25 -/3.97 G -F
08/94 -/17 -/4.63 F
UT Cascade Cr (fam ily cabins) Stokes B-4 06/95 37/15 4.34/1.96 G -F
Cascade Cr SR 2012 Stokes B-5 22-12-(2) 06/95 54/26 2.96/1.98 G
09/90 -/23 -/2.99 G -F
Cascade Cr Near SR 1001 Stokes B-6 22-12-(2) 03/91 -/26 -/2.94 G
09/90 -/26 -/3.48 G
Cascade Cr
(above sw imming lake)
Stokes B-7 22-12-1 06/95 69/31 3.35/1.77 E
03/93 -/34 -/1.61 E
08/91 -/26 -/1.59 G
03/91 -/35 -/1.69 E
09/90 -/22 -/1.88 G
Indian Cr (above trail)Stokes B-8 22-13-(1) 03/93 -/30 -/1.47 E
03/91 -/25 -/1.38 G
Indian Cr (below trail)Stokes B-9 22-13-(1) 03/93 -/34 -/1.54 E
03/91 -/27 -/1.22 E
09/90 -/26 -/2.57 E
Indian Cr SR 1001 Stokes B-10 22-13-(2) 09/90 -/22 -/2.33 G
Indian Cr SR 1487 Stokes B-11 22-13-(2) 09/90 -/27 -/2.76 G
Snow Cr SR 1673 Stokes B-12 22-20 08/00 G
08/99 -/18 -/4.37 F
08/94 -/22 -/4.00 G -F
Town Fk Cr SR 1970 Stokes B-13 22-25 09/95 -/7-/5.95 P
Town Fk Cr SR 1961 Stokes B-14 22-25 09/95 89/26 5.17/4.77 G -F
Town Fk Cr SR 1955 Stokes B-15 22-25 09/95 -/26 -/4.69 G -F
Town Fk Cr US 311 Stokes B-16 22-25 02/88 -/19 -/4.43 G -F
Town Fk Cr SR 1917 Stokes B-17 22-25 08/94 -/15 -/4.59 G -F
02/88 -/24 -/4.21 G -F
Neatm an Cr SR 1961 Stokes B-18 22-25-6 09/95 -/29 -/4.27 G
UT Dan R, US 311 Stokes B-19 22-(28.5) 02/87 -/21 -/4.00 G -F
UT Dan R (near raceway) Stokes B-20 22-(28.5) 02/87 -/15 -/4.40 F
03-02-02
Mayo RSR 1358 Rockingham B-1 22-30-(1) 08/99 70/32 4.26/3.44 G
08/94 64/38 3.60/3.24 G
08/89 79/42 4.78/4.02 G
03/89 96/54 3.72/2.85 G
07/87 87/40 4.78/4.10 G
07/86 102/37 5.07/3.95 G
Mayo R NC 770 Rockingham B-2 22-30-(1) 03/89 -/37 -/3.49 G -F
Mayo RUS 220 Bus R ockingham B-3 22-30-(1) 03/89 -/44 -/3.29 G -F
Mayo R NC 135 Rockingham B-4 22-30-(10) 08/89 -/28 -/4.12 G
Mayo RSR 2177 Rockingham B-5 22-30-(10) 08/99 52/21 5.22/4.25 G -F
09/94 71/33 4.70/4.33 G
03-02-03
Dan RSR 2150 Rockingham B-1 22-(31.5) 08/89 64/26 5.50/4.66 G
07/87 92/32 5.67/4.61 G
Dan RSR 1761 Rockingham B-2 22-(39) 08/91 55/26 5.07/4.30 E
07/87 68/26 5.14/4.15 G
07/86 61/20 5.87/4.64 G -F
09/84 56/17 5.71/4.41 G -F
08/83 65/22 5.53/4.70 G
A-II-5
Subbasin/
Stream Location County
Site
No.
Index
No. Date
S/
EPT S
NCBI/
EPT BI
Bio
Class1
03-02-03 (con’t)
Smith R (near NC/VA state line) VA 922 B-3 22-40-(1) 09/84 63/21 5.74/4.42 G -F
Smith R NC 14 R ockingham B-4 22-40-(3) 09/99 51/18 5.23/3.67 F
08/94 58/18 5.66/4.43 F
07/90 81/31 5.52/4.18 G -F
07/88 69/24 6.03/5.08 F
07/86 57/18 6.14/4.71 F
Wolf Island Cr NC 700 CaswellB-5 22-48 07/88 82/24 5.81/4.82 G
07/85 68/25 5.40/4.69 G
08/83 76/24 5.52/4.53 G
UT Hogans Cr VA 736 PittsylvaniaB-6 22-50 06/98 44/16 4.94/4.04 NR
11/96 48/12 6.15/4.71 NR
UT Hogans Cr (above ponds) O ff SR 1503 CaswellB-7 22-50 06/98 43/13 5.25/4.61 NR
11/96 36/10 6.13/4.92 NR
UT Hogans Cr (below ponds) O ff SR 1503 CaswellB-8 22-50 06/98 48/12 5.89/5.67 NR
11/96 41/76.42/3.95 NR
Jones Cr SR 2632 Rockingham B-9 22-50-3 01/92 -/29 -/4.56 G
Jones Cr SR 2571 Rockingham B-10 22-50-3 12/87 83/27 5.55/4.50 G
03-02-04
Dan R NC 57 CaswellB-1 22-39 08/99 66/32 5.42/4.54 G
Country Line Cr NC 57 CaswellB-2 22-56-(3.7) 08/94 -/14 -/4.42 G -F
07/90 73/26 5.51/4.52 G
07/87 78/26 5.77/4.95 G
08/83 72/19 5.80/4.34 G -F
03-02-05
H yco Cr (North Hyco Cr)US 158 CaswellB-1 22-58-1 08/94 -/10 -/5.93 F
07/90 65/20 5.91/5.27 G -F
07/87 74/23 5.86/5.15 G -F
07/86 78/21 5.88/5.07 G -F
Marlowe Cr SR 1322 Person B -2 22-58-12-6 08/99 53/96.34/5.74 F
08/94 33/56.90/6.49 P
03-02-06
Island Cr SR 1445 G ranvilleB-1 23-4 08/94 -/17 -/5.10 G -F
L Island Cr SR 1342 Vance B-2 23-4-3 05/88 -/21 -/4.88 G -F
Nutbush Cr (above W W TP) NC 39 Vance B-3 23-8-(1) 11/94 58/12 6.89/6.13 F
10/94 54/12 6.96/5.77 F
05/88 44/67.40/6.75 F
Nutbush Cr (below WWTP) Off NC 39 Vance B-4 23-8-(1) 11/94 48/77.19/6.20 F
Nutbush Cr SR 1317 Vance B-5 23-8-(1) 08/99 41/86.72/6.75 F
10/94 50/86.74/6.31 F
08/94 44/86.83/6.88 F
05/88 35/38.14/6.45 P
Anderson Swam p Cr I-85 Vance B-6 23-8-6-(1) 02/90 49/13 6.98/5.71 NR
UT Anderson Swamp Cr US 1/158 Vance B-7 23-8-6-(1) 02/90 18/27.55/7.75 NR
03-02-07
Smith Cr US 1Warren B-1 23-10 07/99 59/12 6.56/5.51 F
08/94 53/66.94/6.15 F
07/89 59/12 6.75/5.06 F
07/86 56/10 6.22/5.13 F
08/84 56/12 6.42/5.36 F
Sixpound Cr SR 1306 W arren B-2 23-13 07/99 54/14 5.50/5.04 G -F
08/94 -/12 -/5.32 F
03-02-08
Deep Cr US 158 Halifax B-1 23-24-(1) 07/99 58/11 6.40/5.17 NR
08/94 64/13 6.36/5.70 F
Roanoke R (below Weldon) US 158 Halifax B-2 23-(26) 09/94 45/16 5.29/4.68 G
Roanoke R (boat access),Halifax B-3 23-(26) 03/99 76/28 5.26/4.36 G
Roanoke RUS 258 Halifax B-4 23-(26) 07/99 41/19 5.21/4.76 G
03/99 67/30 5.37/4.72 G
09/94 45/16 4.90/4.28 G
A-II-6
Subbasin/
Stream Location County
Site
No.
Index
No. Date
S/
EPT S
NCBI/
EPT BI
Bio
Class1
03-02-08 (con’t)
Smith R (near NC/VA state line) VA 922 B-3 22-40-(1) 09/84 63/21 5.74/4.42 G -F
07/85 49/16 5.92/4.88 G -F
Q uankey Cr NC 903 Halifax B-5 23-30 02/99 40/96.66/5.92 NR
Q uankey Cr NC 561 Halifax B-6 23-30 09/99 -/9-/5.51 F
Q uankey Cr (above WWTP) Halifax B-7 23-30 12/92 51/76.55/5.69 F
Q uankey Cr (below WWTP) Halifax B-8 23-30 12/92 57/96.41/5.28 F
O coneechee Cr SR 1126 Northam pton B-9 23-31 02/99 22/46.48/6.85 NR
Conoconnara Swp NC 561, Halifax B-10 23-33 02/99 31/56.44/6.80 NR
07/84 39/37.49/6.26 NR
Kehukee Swp SR 1804 Halifax B-11 23-42 09/99 -/6-/6.19 NR
02/99 59/87.10/6.44 NR
03-02-09
Roanoke R (below Hamilton), NC 125/903 M artinB-1 23-(26) 03/99 61/23 5.82/4.80 G -F
09/94 51/19 5.21/4.39 G
Roanoke R (below William ston) US 17 M artinB-2 23-(26) 07/99 45/17 5.96/4.77 G -F
03/99 73/23 6.32/5.07 G -F
09/94 53/17 5.70/4.80 G -F
Indian Cr SR 1108 BertieB-3 23-47 03/97 30/17.40/7.78 NR
Conoho Cr NC 125/903 M artinB-4 23-49 02/99 29/37.28/7.56 NR
08/94 23/07.49/-NR
Conoho Cr SR 1417 M artinB-5 23-49 02/99 39/56.26/4.80 NR
Hardison Mill Cr NC 171 M artinB-6 23-50-3 02/99 24/27.69/7.65 NR
Hardison Mill Cr SR 1528 M artinB-7 23-50-3 02/99 27/37.28/7.65 NR
Deep Run Swp NC 171 M artinB-8 23-52-1-1 02/99 21/17.61/7.78 NR
Welch Cr SR 1552 M artinB-9 23-55 02/99 32/37.20/6.92 NR
Roanoke R NC 45 BertieB-10 23-(53) 07/99 59/97.35/6.56 NR
09/94 52/97.52/6.08 NR
06/92 60/87.48/5.82 NR
07/90 51/10 7.48/6.23 NR
07/88 60/77.93/6.62 NR
07/86 50/87.68/6.77 NR
07/85 37/48.16/6.50 NR
07/84 42/67.63/6.18 NR
07/83 38/68.07/5.42 NR
Conaby Cr SR 1114 W ashington B-11 23-56 04/94 68/57.015.89 NR
Conaby Cr SR 1325 W ashington B-12 23-56 04/94 41/07.44/-NR
03-02-10
Cashie R (above WWTP) off NC 11 BertieB-1 24-2-(1) 06/84 37/08.61/-NR
Cashie R (below WWTP) off NC 11 BertieB-2 24-2-(1) 06/84 41/08.39/-NR
Cashie RSR 1219 BertieB-3 24-2-(1) 02/99 41/67.47/7.23 NR
06/84 43/28.247.00 NR
07/83 34/28.54/7.00 NR
Cashie RSR 1257 BertieB-4 24-2-(1) 02/99 34/76.78/6.09 NR
Hoggard Mill Cr SR 1301 BertieB-5 24-2-6 02/99 46/76.74/6.37 NR
W ading Place Cr NC 308 BertieB-6 24-2-8 03/99 35/37.35/7.42 NR
Roquist Swp US 13/17 BertieB-7 24-2-8 02/99 31/46.98/5.48 NR
Cashie RSR 1500 BertieB-8 24-2-(9) 09/94 56/98.10/6.34 NR
1 E = Excellent, G = G ood,
G-F = G ood-Fair, F = Fair, P = Poor, and NR = Not Rated.
A-II-7
Fish Community Sampling Methodology and Bioclassification Criteria
At each sample site, a 600-foot section of stream is measured and selected. Fish in the
delineated stretch of stream are then collected using two backpack electrofishing units and two
persons netting the stunned fish. After collection, all readily identifiable fish are examined for
sores, lesions, fin damage, or skeletal anomalies, measured (total length to the nearest 1 mm),
and then released. Those fish that are not readily identifiable are preserved and returned to the
laboratory for identification, examination, and measurement. Detailed descriptions of the
sampling methods may be found on the Environmental Sciences Branch website:
http://www.esb.enr.state.nc.us/BAUwww/IBI%20Methods%202.pdf.
The assessment of biological integrity using the North Carolina Index of Biotic Integrity
(NCIBI) is provided by the cumulative assessment of 12 parameters or metrics. The values
provided by the metrics are converted into scores on a 1, 3 or 5 scale. A score of 5 represents
conditions which would be expected for undisturbed reference streams in the specific river basin
or ecoregion, while a score of 1 indicates that the conditions deviate greatly from those expected
in undisturbed streams of the region. Each metric is designed to contribute unique information to
the overall assessment. The scores for all metrics are then summed to obtain the overall NCIBI
score. Finally, the score (an even number between 12 and 60) is then used to determine the
ecological integrity class, as proposed by Karr (1981), of the stream from which the sample was
collected (Table A-II-2).
Table A-II-2 Original Scores, Integrity Classes, and Class Attributes for Evaluating Fish
Communities Using Karr’s 1981 Index of Biotic Integrity
NCIBI
Scores
Integrity
Classes Class Attributes*
> 58 Excellent Comparable to the best situations without human disturbance. All regionally expected
species for the habitat and stream size, including the most intolerant forms are present,
along with a full array of size classes and a balanced trophic structure.
48-52 Good Species richness somewhat below expectation, especially due to the loss of the most
intolerant species; some species are present with less than optimal abundances or size
distributions; and the trophic structure shows some signs of stress.
40-44 Fair Signs of additional deterioration include the loss of intolerant species, fewer species,
and a highly skewed trophic structure.
28-34 Poor Dominated by omnivores, tolerant species, and habitat generalists; few top carnivores;
growth rates and condition factors commonly depressed; and diseased fish often
present.
< 22 Very Poor Few fish present, mostly introduced or tolerant species; and disease fin damage and
other anomalies are regular.
----- No fish Repeated sampling finds no fish.
* Over-lapping classes share attributes with classes greater than and less than the respective IBI score.
The NCIBI has been revised since the 1997 Standard Operating Procedures were printed
(NCDEHNR 1997). Recently, the focus of using and applying the NCIBI has been restricted to
wadeable streams that can be sampled by a crew of four persons. The bioclassifications and
criteria have also been re-calibrated against regional reference site data (Table A-II-3).
A-II-8
Table A-II-3 Revised Scores and Classes for Evaluating the Fish Community of a Wadeable
Stream Using the NCIBI in the Piedmont Portion of the Cape Fear, Neuse,
Roanoke and Tar River Basins
NCIBI Scores NCIBI Classes
> 54 Excellent
46 - 52 Good
40 - 44 Good-Fair
34 - 38 Fair
≤ 32 Poor
The definition of the piedmont for these four river basins is based upon a map of North Carolina
watersheds by Fels (1997). Specifically for the Roanoke River basin, the piedmont encompasses
the entire basin above Roanoke Rapids, NC and a small area between Roanoke Rapids and
Halifax, NC.
Work began in 1998 to develop a fish community boat sampling method that could be used in
non-wadeable coastal plain streams. Plans are to sample 10-15 reference sites with the boat
method once it is finalized. As with the benthos in swamp streams, several years of reference
site data will be needed before criteria can be developed with confidence to evaluate the
biological integrity of large streams and rivers, like the Roanoke River, using the fish
community.
Table A-II-4 Fish Community Data Collected in the Roanoke River Basin, 1990-1999
(Sites sampled during the current five-year basinwide cycle are bolded.)
Subbasin Waterbody Station County Date NCIBI Rating
03-02-02 Paw Paw Cr SR 1360 Rockingham 08/90 Good
03-02-03 Wolf Island Cr NC 700 Caswell 10/94 Excellent
03-02-04 Cane Cr SR 1527 Caswell 10/94 Good-Fair
03-02-04 Country Line Cr NC 57 Caswell 09/94 Good
03-02-04 Moon Cr SR 1511 Caswell 09/94 Good
03-02-05 Marlowes Cr SR 1322 Person 09/94 Good-Fair
03-02-06 Grassy Cr SR 1300 Granville 06/99 Good
SR 1436 Granville 06/94 Good
03-02-06 Island Cr SR 1445 Granville 06/99 Excellent
06/94 Good
03-02-06 Nutbush Cr SR 1317 Vance 10/94 Good-Fair
03-02-07 Six Pound Cr SR 1306 Warren 05/94 Good-Fair
03-02-07 Smith Cr US 1 Warren 05/94 Good-Fair
03-02-08 Conoconnara Swp NC 561 Halifax 09/94 Not Rated
03-02-08 Deep Cr US 158 Halifax 09/94 Good
03-02-08 Kehukee Swp SR 1804 Halifax 10/94 Not Rated
03-02-08 Quankey Cr SR 1619 Halifax 09/94 Good-Fair
03-02-10 Cashie R SR 1257 Bertie 10/94 Not Rated
A-II-9
Fish Tissue Criteria
In evaluating fish tissue analysis results, several different types of criteria are used. Human
health concerns related to fish consumption are screened by comparing results with:
• Federal Food and Drug Administration (FDA) action levels.
• Environmental Protection Agency (EPA) recommended screening values.
• Criteria adopted by the North Carolina State Health Director.
Sample results which exceed these levels are a human health concern and are evaluated by the
NC Division of Occupational and Environmental Epidemiology at DWQ’s request. The FDA
levels were developed to protect humans from the chronic effects of toxic substances consumed
in foodstuffs, and thus, employ a "safe level" approach to fish tissue consumption. Presently, the
FDA has only developed metals criteria for mercury.
The EPA has recommended screening values for target analytes which are formulated from a risk
assessment procedure (EPA, 1995). These are the concentrations of analytes in edible fish tissue
that are of potential public health concern. DWQ compares fish tissue results with EPA
screening values to evaluate the need for further intensive site-specific monitoring.
Table A-II-5 Fish Tissue Criteria
Contaminant FDA
Action Levels
US EPA
Screening Values
NC
Health Director
Metals
Cadmium -- 10.0 --
Mercury 1.0 0.6 --
Selenium -- 50.0 5.0
Organics
Aldrin 0.3 -- --
Chlorpyrifos -- 30 --
Total chlordane 1 -- 0.08 --
Cis-chlordane 0.3 -- --
Trans-chlordane 0.3 -- --
Total DDT 2 -- 0.3 --
Dieldrin -- 0.007 --
Dioxins (total) -- 0.7 3.0
Endosulfan (I and II) -- 60.0 --
Endrin 0.3 3.0 --
Heptachlorepoxide -- 0.01 --
Hexachlorobenzene -- 0.07 --
Lindane -- 0.08 --
Mirex -- 2.0 --
Total PCBs -- 0.01 --
PCB-1254 2.0 -- --
Toxaphene -- 0.1 --
1 Total chlordane includes the sum of cis-and trans- isomers as well as nonachlor and oxychlordane.
2 Total DDT includes the sum of all its isomers and metabolites (i.e., p,p DDT, o,p DDT, DDE,
and DDD).
Note: All wet weight concentrations are reported in parts per million (ppm,
dioxin which is in parts per trillion (ppt, pg/g).
The North Carolina State Health Director has adopted a selenium limit of 5 µg/g for issuing an
advisory. Although the EPA has suggested a screening value of 0.7 ppt (pg/g) for dioxins, the
State of North Carolina currently uses a value of 3.0 ppt in issuing an advisory.
A-II-10
Table A-II-6 Wet Weight Concentrations of Mercury (Hg), Arsenic (As) and Cadmium (Cd) in
Fish Tissue from the Roanoke River Basin (1994 – 1999)
Subbasin/
Site CountyDate Species
Total
Length
(cm )
Weight
(g)
Hg
(
As
(
Cd
(
03-02-03
Dan River near Eden Rockingham 08/31/1999 Bluegill 16 77 0.05 ND
1 ND1
Channel catfish 35.5 358 0.10 ND ND
Golden redhorse 37.8 335 0.36 ND ND
Golden redhorse 33 387 0.17 ND ND
Golden redhorse 31.2 300 0.27 ND ND
Golden redhorse 33.5 378 0.23 ND ND
Golden redhorse 37.1 476 0.37 ND ND
Golden redhorse 34.3 426 0.17 ND ND
Largemouth bass 30 374 0.20 ND ND
Largemouth bass 28.2 304 0.13 ND ND
Largemouth bass 27.5 260 0.12 ND ND
Quillback 38.2 796 0.29 ND ND
Redbreast sunfish 16.3880.07 ND ND
Redbreast sunfish 13.2 44.20.10 ND ND
Redear sunfish 15.7 73.50.04 ND ND
Golden redhorse 37.8 414 0.22 ND ND
Snail bullhead 30.1 369 0.03 ND ND
Snail bullhead 31 346 0.03 ND ND
White catfish 29 334 0.16 ND ND
03-02-06
Kerr Lake at m outh
of Nutbush Cr
Vance 05/20/1999 Bluegill 18.4 125 0.12 ND ND
Chain pickerel 57 1552 0.39 ND ND
Chain pickerel 53 1219 0.31 ND ND
Largemouth bass 46.5 1470 0.56 ND ND
Largemouth bass 42 1121 0.51 ND ND
Largemouth bass 43.8 984 0.65 ND ND
Largemouth bass 38 671 0.41 ND ND
Largemouth bass 38.5 767 0.59 ND ND
Largemouth bass 31 500 0.35 ND ND
Largemouth bass 33.6 477 0.52 ND ND
Largemouth bass 30.5 412 0.34 ND ND
Largemouth bass 31.5 423 0.26 ND ND
Largemouth bass 29.5 401 0.28 ND ND
Redear sunfish 27.5 377 0.06 ND ND
Redear sunfish 26.8 419 0.11 ND ND
Redear sunfish 22 179 0.08 ND ND
White catfish 27 241 0.34 ND ND
01/28/1999 Striped bass 70
Striped bass 467
Striped bass 48.2
Striped bass 42.5
Striped bass 73.2
Striped bass 41
Striped bass 77.1
Striped bass 65
Striped bass 44.6
Striped bass 67
Striped bass 41.7
Striped bass 44.3
Striped bass 74.8
Striped bass 39.5
Striped bass 42.4
Striped bass 70.1
Striped bass 72.2
Striped bass 44.5
Striped bass 78.2
A-II-11
Subbasin/
Site CountyDate Species
Total
Length
(cm )
Weight
(g)
Hg
(
As
(
Cd
(
03-02-07
Lake Gaston near Halifax 07/08/1999 Bluegill 17.5 104.60.05 ND ND
Henrico Bluegill 18.1 119.30.05 ND ND
Bluegill 14.8 76.50.03 ND ND
Channel catfish 49.2 1096 0.05 ND ND
Channel catfish 48.2 1013 0.21 ND ND
Channel catfish 48.5 1172 0.05 ND ND
Channel catfish 43.5 804 0.10 ND ND
Channel catfish 47.8 1136 0.07 ND ND
Largemouth bass 25 212 0.07 ND ND
Largemouth bass 29.5 343 0.10 ND ND
Largemouth bass 31.1 423 0.07 ND ND
Largemouth bass 36.2 612 0.29 ND ND
Largemouth bass 42.6 962 0.37 ND ND
Largemouth bass 38.2 797 0.19 ND ND
Largemouth bass 37.4 728 0.14 ND ND
Largemouth bass 40.1 979 0.24 ND ND
Largemouth bass 45.3 1077 0.20 ND ND
Largemouth bass 45 1585 0.27 ND ND
Yellow perch 19.7 87.30.05 ND ND
Yellow perch 24.4 169 0.12 ND ND
03-02-08
Roanoke River at
Weldon
Halifax 05/19/99 Bluegill 14.9 66.60.07 ND ND
Bluegill 15.7 77.50.06 ND ND
Black crappie 25.1 254 0.28 ND ND
Largemouth bass 43.1 1193 0.57 ND ND
Largemouth bass 40.7 1095 0.33 ND ND
Largemouth bass 38.2 657 0.43 ND ND
Largemouth bass 30.2 371 0.29 ND ND
Largemouth bass 32.3 412 0.43 ND ND
Largemouth bass 29.3 330 0.33 ND ND
Largemouth bass 25.3 244.50.23 ND ND
Largemouth bass 21.9 139.50.18 ND ND
Redbreast sunfish 17 92 0.10 ND ND
Striped bass 47.5 1256 0.20 ND ND
Striped bass 43.8 986 0.21 ND ND
Striped bass 45.3 907 0.24 ND ND
Striped bass 42.8 732 0.20 ND ND
Striped bass 39.7 661 0.19 ND ND
Striped bass 43.1 1540 0.51 ND ND
White catfish 37.5 575 0.07 ND ND
White catfish 33.8 528 0.15 ND ND
Yellow perch 23.8 188 0.17 ND ND
09/20/1995 Bowfin 39.5 621 0.13 ----
Bowfin 42 686 0.13 ----
Bowfin 46 992 0.11 ----
Bowfin 53.5 1223 0.67 ----
Bowfin 64 2701 0.68 ----
Bowfin 57.5 2394 0.56 ----
A-II-12
Subbasin/
Site CountyDate Species
Total
Length
(cm )
Weight
(g)
Hg
(
As
(
Cd
(
03-02-08 (con’t)
Roanoke River at
Scotland Neck
Halifax 05/19/99 Bowfin 58 1847 0.52 ND ND
Bowfin 55 1417 0.47 ND ND
Bowfin 60.1 2010 1.1ND ND
Bowfin 50 1100 0.39 ND ND
Bowfin 54.9 1429 0.41 ND ND
Bowfin 49.5 1349 0.57 ND ND
Bluegill 17.5 116 0.14 ND ND
Channel catfish 54.8 1654 0.15 ND ND
Channel catfish 43.5 641 0.10 ND ND
Largemouth bass 40.2 966 0.71 ND ND
Largemouth bass 32.5 533 0.46 ND ND
Largemouth bass 31.2 412 0.52 ND ND
Redbreast sunfish 18.9 167 0.06 ND ND
Striped bass 49 1245 0.26 ND ND
Striped bass 45.2 1004 0.28 ND ND
Striped bass 48 1128 0.20 ND ND
Striped bass 47 1082 0.11 ND ND
Striped bass 45 1054 0.18 ND ND
Striped bass 43.2 835 0.15 ND ND
Striped bass 43.5 901 0.10 ND ND
Striped bass 41.1 652 0.26 ND ND
White catfish 36 712 0.42 ND ND
White catfish 28.7 305.50.19 ND ND
03-02-09
Roanoke River at
Plym outh
Washington 07/21/1999 Bowfin 55.5 1738 0.56 ND ND
Bowfin 52.5 1321 0.47 ND ND
Bowfin 45.7 837 0.50 ND ND
Bowfin 42.5 690 0.31 ND ND
Bluegill 17.9 133.60.07 ND ND
Chain pickerel 47.8 640 0.64 ND ND
Largemouth bass 41.6 1165 0.44 ND ND
Largemouth bass 44.1 1282 0.53 ND ND
Largemouth bass 39.3 924 0.68 ND ND
Largemouth bass 37.6 759 0.48 ND ND
Largemouth bass 37.2 797 0.40 ND ND
Largemouth bass 37.1 821 0.64 ND ND
Largemouth bass 39 619 0.84 ND ND
Largemouth bass 37.6 703 0.49 ND ND
Largemouth bass 33.2 484 0.42 ND ND
Largemouth bass 28.9 342 0.45 ND ND
Largemouth bass 36.2 639 0.36 ND ND
Redear sunfish 25.5 313 0.13 ND ND
Redear sunfish 26.1 338 0.22 ND ND
Redear sunfish 19.4 140 0.12 ND ND
Yellow perch 23.6 190.30.20 3.9ND
Yellow perch 20.1 119 0.16 ND ND
07/06/1995 Bowfin 44.8 900 0.43 ----
Bowfin 54 1500 0.37 ----
Bowfin 54.7 1700 0.45 ----
Bowfin 52.1 1200 0.6----
Bowfin 67.1 3000 1 ----
Bowfin 69.5 3500 1.5----
Bowfin 72.6 3900 1.2----
A-II-13
Subbasin/
Site CountyDate Species
Total
Length
(cm )
Weight
(g)
Hg
(
As
(
Cd
(
03-02-09 (con’t)
Roanoke River at US-17 M artin 07/06/1999 Bowfin 57.3 1815 0.65 ND ND
Bowfin 57 1959 0.76 ND ND
Bowfin 65.1 2633 1.3ND ND
Bluegill 23 290 0.30 ND ND
Bluegill 18.8 150.50.30 ND ND
Bluegill 17.6 132 0.17 ND ND
Bluegill 16.8990.27 ND ND
Largemouth bass 44.8 1226 1.3ND ND
Largemouth bass 42.1 1090 1.4ND ND
Largemouth bass 36.5 853 0.86 ND ND
Largemouth bass 39.7 894 0.94 ND ND
Largemouth bass 37.1 850 0.76 ND ND
Largemouth bass 35.1 692 0.94 ND ND
Largemouth bass 33 574 0.82 ND ND
Largemouth bass 33.8 704 0.75 ND ND
Largemouth bass 33 525 0.68 ND ND
Largemouth bass 26.4 253 0.44 ND ND
Largemouth bass 22.5 155 0.35 ND ND
Redear sunfish 20.9 187 0.19 ND ND
White catfish 38 768 0.64 ND ND
White catfish 35 588 0.67 ND ND
White catfish 36.2 610 0.39 ND ND
White catfish 33.1 518 0.67 ND ND
White catfish 33.2 408 0.31 ND ND
07/06/1995 Bowfin 51.1 110 0.85 ----
Bowfin 53 1200 0.84 ----
Bowfin 54.5 1300 0.85 ----
Bowfin 53.3 1300 0.84 ----
Bowfin 54.1 1200 0.98 ----
Bowfin 69.5 2800 2.4----
Bowfin 58.1 1700 1.2----
Bowfin 67.3 2400 2.2----
03-02-10
Cashie River at Windsor Bertie 07/21/1999 Bowfin 54.5 1426 1.5ND ND
Bowfin 53 1495 1.5ND ND
Bowfin 53 1468 1.3ND ND
Bowfin 50.5 1239 1.0ND ND
Bowfin 41 663 0.69 ND ND
Bowfin 41.5 649 0.67 ND ND
Bluegill 22.1 202 0.68 ND ND
Bluegill 16.8 205 0.31 ND ND
Bluegill 15.5780.20 ND ND
Black crappie 22.1 183.50.45 ND ND
Black crappie 19.9 118 0.24 ND ND
Brown bullhead 37.5 694.30.17 ND ND
Chain pickerel 39.6 435 0.80 ND ND
Largemouth bass 50.7 2201 1.4ND ND
Largemouth bass 51.5 2185 1.9ND ND
Largemouth bass 42 1088 0.64 ND ND
Largemouth bass 33.7 503 1.1ND ND
Largemouth bass 29 350 0.58 ND ND
Largemouth bass 30.1 420 0.44 ND ND
Largemouth bass 27 285 0.42 ND ND
Largemouth bass 29.8 325 0.65 ND ND
Largemouth bass 27.4 279 0.44 ND ND
Largemouth bass 25.1 219 0.49 ND ND
Yellow bullhead 32.3 498 0.56 ND ND
1 ND = non-detect; detection level for arsenic = 1.0
A-II-14
Table A-II-7 Wet Weight Concentrations of PCBs in Fish Tissue from John H. Kerr Reservoir
at the Mouth of Nutbush Creek, Vance County (1999)
Date
Sam pled Species Total
Length (mm)
Weight
(g)
PCB
(1
01/28/1999 Striped bass 467 --- ND
01/28/1999 Striped bass 482 --- ND
01/28/1999 Striped bass 425 --- ND
01/28/1999 Striped bass 732 --- ND
01/28/1999 Striped bass 410 --- ND
01/28/1999 Striped bass 771 --- ND
01/28/1999 Striped bass 650 --- ND
01/28/1999 Striped bass 446 --- ND
01/28/1999 Striped bass 670 --- ND
01/28/1999 Striped bass 417 --- ND
01/28/1999 Striped bass 443 --- ND
01/28/1999 Striped bass 748 --- ND
01/28/1999 Striped bass 395 --- ND
01/28/1999 Striped bass 424 --- ND
01/28/1999 Striped bass 701 --- ND
01/28/1999 Striped bass 722 --- ND
01/28/1999 Striped bass 445 --- ND
01/28/1999 Striped bass 782 --- 0.162
01/28/1999 Striped bass 700 --- 0.222
05/20/1999 Largemouth bass 465 1470 ND
05/20/1999 Largemouth bass 420 1121 ND
05/20/1999 Largemouth bass 438 984 ND
05/20/1999 Largemouth bass 380 671 ND
05/20/1999 Largemouth bass 385 767 ND
1 ND = not detected; detection level was 0.125
A-II-15
Lakes Assessments
Numerical indices are often used to evaluate the trophic state of lakes. An index was developed
specifically for North Carolina lakes as part of the state’s original Clean Lakes Classification
Survey. The North Carolina Trophic State Index (NCTSI) is based on total phosphorus (TP in
mg/l), total organic nitrogen (TON in mg/l), Secchi depth (SD in inches), and chlorophyll a
(CHL in µg/L). Lakewide means for these parameters are used to produce a NCTSI score for
each lake, using the equations:
TONScore = ((Log (TON) + 0.45)/0.24)*0.90
TPScore = ((Log (TP) + 1.55)/0.35)*0.92
SDScore = ((Log (SD) – 1.73)/0.35)*-0.82
CHLScore = ((Log (CHL) – 1.00)/0.48)*0.83
NCTSI= TONScore + TPScore + SDScore + CHLScore
In general, NCTSI scores relate to trophic classifications (Table A-II-8). When scores border
between classes, best professional judgment is used to assign an appropriate classification.
NCTSI scores may be skewed by highly colored water typical of dystrophic lakes. Some
variation in the trophic state of a lake between years is not unusual because of the potential
variability of data collections which usually involve sampling a limited number of times during
the growing season.
Table A-II-8 Lakes classification criteria
NCTSI Score Trophic Classification
< -2.0 Oligotrophic
-2.0 – 0.0 Mestrophic
0.0 – 5.0 Eutrophic
> 5.0 Hypereurtrophic