2001 Roanoke Sec A Chap 3

Section A: Chapter 3 – Summary of Water Quality Information for the Roanoke River Basin 42
Chapter 3 -
Summary of Water Quality Information for the
Roanoke River Basin
3.1 General Sources of Pollution
Human activities can negatively impact
surface water quality, even when the
activity is far removed from the
waterbody. With proper management
of wastes and land use activities, these
impacts can be minimized. Pollutants
that enter waters can be grouped into
two general categories: point sources
and nonpoint sources.
Point sources are typically piped discharges and are controlled through regulatory programs
administered by the state. All regulated point source discharges in North Carolina must apply for
and obtain a National Pollutant Discharge Elimination System (NPDES) permit from the state.
Nonpoint sources are from a broad range of land use
activities. Nonpoint source pollutants are typically
carried to waters by rainfall, runoff or snowmelt.
Sediment and nutrients are most often associated with
nonpoint source pollution. Other pollutants associated
with nonpoint source pollution include fecal coliform
bacteria, heavy metals, oil and grease, and any other
substance that may be washed off the ground or
deposited from the atmosphere into surface waters.
Unlike point source pollution, nonpoint pollution sources are diffuse in nature and occur
intermittently, depending on rainfall events and land disturbance. Given the diffuse nature of
nonpoint source pollution, it is difficult and resource intensive to quantify nonpoint contributions
to water quality degradation in a given watershed. While nonpoint source pollution control often
relies on voluntary actions, the state has many programs designed to reduce nonpoint source
pollution.
Every person living in or visiting a watershed
contributes to impacts on water quality. Therefore,
each individual should be aware of these contributions
and take actions to reduce them.
Point Sources
• Piped discharges from municipal wastewater
treatment plants
• Industrial facilities
• Small package treatment plants
• Large urban and industrial stormwater systems
Nonpoint Sources
• Stormwater runoff
• Agricultural lands
• Rural residential development
• Hydrologic modifications
• Septic systems
• Timber harvesting
Cumulative Effects
While any one activity may not have a
dramatic effect on water quality, the
cumulative effect of land use activities
in a watershed can have a severe and
long-lasting impact.
Section A: Chapter 3 – Summary of Water Quality Information for the Roanoke River Basin 43
3.2 Description of Surface Water Classifications and Standards
North Carolina’s Water Quality Standards program adopted classifications and water quality
standards for all the state’s river basins by 1963. The program remains consistent with the
Federal Clean Water Act and its amendments. Water quality classifications and standards have
also been modified to promote protection of surface water supply watersheds, high quality
waters, and the protection of unique and special pristine waters with outstanding resource values.
Statewide Classifications
All surface waters in the state are assigned a primary classification that is appropriate to the best
uses of that water. In addition to primary classifications, surface waters may be assigned a
supplemental classification. Most supplemental classifications have been developed to provide
special protection to sensitive or highly valued resource waters. Table A-20 briefly describes the
best uses of each classification. A full description is available in the document titled:
Classifications and Water Quality Standards Applicable to Surface Waters of North Carolina.
Information, including a database of North Carolina’s stream classifications, is also available on
DWQ’s website at http://h2o.enr.state.nc.us/csu/.
Table A-20 Primary and Supplemental Surface Water Classifications
PRIMARY FRESHWATER AND SALTWATER CLASSIFICATIONS*
Class Best Uses
C and SC Aquatic life propagation/protection and secondary recreation.
B and SB Primary recreation and Class C uses.
SA Waters classified for commercial shellfish harvesting.
WS Water Supply watershed. There are five WS classes ranging from WS-I through WS-V. WS
classifications are assigned to watersheds based on land use characteristics of the area. Each water
supply classification has a set of management strategies to protect the surface water supply. WS-I
provides the highest level of protection and WS-IV provides the least protection. A Critical Area
(CA) designation is also listed for watershed areas within a half-mile and draining to the water
supply intake or reservoir where an intake is located.
SUPPLEMENTAL CLASSIFICATIONS
Class Best Uses
Sw Swamp Waters: Recognizes waters that will naturally be more acidic (have lower pH values) and
have lower levels of dissolved oxygen.
Tr Trout Waters: Provides protection to freshwaters for natural trout propagation and survival of
stocked trout.
HQW High Quality Waters: Waters possessing special qualities including excellent water quality, Native
or Special Native Trout Waters, Critical Habitat areas, or WS-I and WS-II water supplies.
ORW Outstanding Resource Waters: Unique and special surface waters which are unimpacted by
pollution and have some outstanding resource values.
NSW Nutrient Sensitive Waters: Areas with water quality problems associated with excessive plant
growth resulting from nutrient enrichment.
* Primary classifications beginning with a "S" are assigned to saltwaters.
Section A: Chapter 3 – Summary of Water Quality Information for the Roanoke River Basin 44
Statewide Water Quality Standards
Each primary and supplemental classification is assigned a set of water quality standards that
establish the level of water quality that must be maintained in the waterbody to support the uses
associated with each classification. Some of the standards, particularly for HQW and ORW
waters, outline protective management strategies aimed at controlling point and nonpoint source
pollution. These strategies are discussed briefly below. The standards for C and SC waters
establish the basic protection level for all state surface waters. With the exception of Sw, all of
the other primary and supplemental classifications have more stringent standards than for C and
SC, and therefore, require higher levels of protection.
Some of North Carolina’s surface waters are relatively unaffected by pollution sources and have
water quality higher than the standards that are applied to the majority of the waters of the state.
In addition, some waters provide habitat for sensitive biota such as trout, juvenile fish, or rare
and endangered aquatic species.
Trout Waters
Different water quality standards for some parameters, such as dissolved oxygen, temperature
and turbidity, have been developed to protect freshwaters for natural trout propagation and
survival of stocked trout. These water quality standards result in more restrictive limits for
wastewater discharges to trout waters (Tr). There are no watershed development restrictions
associated with the Tr classification. However, the NC Division of Land Resources does require
a 25-foot vegetated buffer between Tr waters and graded construction sites.
A state fishery management classification, Designated Public Mountain Trout Waters, is
administered by the NC Wildlife Resources Commission. It provides for public access to
streams for fishing and regulates fishing activities (seasons, size limits, creel limits, and bait and
lure restrictions). Although many of these waters are also classified Tr by DWQ, this is not the
same classification.
High Quality Waters
Special HQW protection management
strategies are intended to prevent
degradation of water quality below
present levels from both point and
nonpoint sources. HQW requirements
for new wastewater discharge facilities
and facilities which expand beyond
their currently permitted loadings
address oxygen-consuming wastes,
total suspended solids, disinfection,
emergency requirements, volume,
nutrients (in nutrient sensitive waters)
and toxic substances.
Criteria for HQW Classification
• Waters rated as Excellent based on DWQ’s
chemical and/or biological sampling.
• Streams designated as native and special native
trout waters or primary nursery areas by the
Wildlife Resources Commission (WRC).
• Waters classified by DWQ as WS-I and WS-II are
HQW by definition, but these waters are not
specifically assigned the HQW classification
because the standards for WS-I and WS-II waters
are sometimes more stringent than those classified
HQW.
Section A: Chapter 3 – Summary of Water Quality Information for the Roanoke River Basin 45
For nonpoint source pollution, development activities which require a Sedimentation and Erosion
Control Plan in accordance with rules established by the NC Sedimentation Control Commission
or an approved local erosion and sedimentation control program, and which drain to and are
within one mile of HQWs, are required to control runoff from the development using either a low
density or high density option. The low density option requires a 30-foot vegetated buffer
between development activities and the stream; whereas, the high density option requires
structural stormwater controls. In addition, the Division of Land Resources requires more
stringent erosion controls for land-disturbing projects within one mile and draining to HQWs.
Outstanding Resource Waters
A small percentage of North Carolina’s surface waters have excellent water quality (rated based
on biological and chemical sampling as with HQWs) and an associated outstanding resource.
The requirements for ORW waters are more
stringent than those for HQWs. Special
protection measures that apply to North
Carolina ORWs are set forth in 15A NCAC 2B
.0225. At a minimum, no new discharges or
expansions are permitted, and a 30-foot
vegetated buffer or stormwater controls for
new developments are required. In some
circumstances, the unique characteristics of the
waters and resources that are to be protected
require that a specialized (or customized)
ORW management strategy be developed.
Water Supply Watersheds
The purpose of the Water Supply Watershed Protection Program is to provide an opportunity for
communities to work with the state to strengthen protection of their water supplies. There are
five water supply classifications (WS-I to WS-V) that are defined according to the amount and
types of permitted point source discharges, as well as requirements to control nonpoint sources of
pollution (Table A-20). Watersheds draining to waters classified WS carry some restrictions on
point source discharges and on many land use activities including urban development,
agriculture, forestry and highway sediment control. Minimum requirements for WS-I to WS-IV
include a 30-foot undisturbed vegetated buffer. The WS-I and WS-II classifications are HQW by
definition because requirements for these levels of water supply protection are at least as
stringent as for HQWs.
Classifications and Standards in the Roanoke River Basin
The waters of the Roanoke River basin have a variety of surface water quality classifications
applied to them. Water supply watersheds range from WS-II to WS-IV. There are currently no
designated High Quality Waters in the basin and only two small segments of Outstanding
Resource Waters which are discussed in the following section. Several miles of stream,
including the Dan River mainstem, in the upper portion of the Dan River watershed are classified
The ORW rule defines outstanding resource
values as including one or more of the
following:
• an outstanding fisheries resource;
• a high level of water-based recreation;
• a special designation such as National Wild
and Scenic River or a National Wildlife
Refuge;
• within a state or national park or forest; or
• a special ecological or scientific significance.
Section A: Chapter 3 – Summary of Water Quality Information for the Roanoke River Basin 46
Trout Waters. Portions of the Roanoke River basin that contain these special classifications are
shown on Figures A-15 and A-16.
Pending and Recent Reclassifications in the Roanoke River Basin
In August of 1998, a portion of two streams, Cascade and Indian Creeks, inside the Hanging
Rock State Park were reclassified Outstanding Resource Waters. In addition to excellent water
quality found in both streams, rare benthic macroinvertebrate species were found in both Cascade
Creek and an unnamed tributary. Both streams were also found to be "important components of
a state park" that have "special ecological significance" in the area.
Parts of some streams located in the lower portion of the Roanoke River basin may qualify for
the Outstanding Resource Waters designation and/or a special set of management strategies
based on their ecological and scientific significance, their presence as part of a National Wildlife
Refuge, and their unique recreational value. Management strategies associated with these
reclassifications would take into account natural variations in these complex swamp stream
systems. Citizens, organizations or local governments can recommend waters for reclassification
at any time, and DWQ will consider them for these protective classifications.
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Section A: Chapter 3 – Summary of Water Quality Information for the Roanoke River Basin 49
3.3 DWQ Water Quality Monitoring Programs in the Roanoke River
Basin
Staff in the Environmental Sciences Branch and
Regional Offices of DWQ collect a variety of
biological, chemical and physical data. The
following discussion contains a brief introduction
to each program, followed by a summary of water
quality data in the Roanoke River basin for that
program. For more detailed information on
sampling and assessment of streams in this basin,
refer to the Basinwide Assessment Report for the
Roanoke River basin, available from the
Environmental Sciences Branch website at
http://www.esb.enr.state.nc.us/bar.html or by calling
[phone].
3.3.1 Benthic Macroinvertebrate Monitoring
Benthic macroinvertebrates, or benthos, are organisms that live in and on the bottom substrates
of rivers and streams. These organisms are primarily aquatic insect larvae. The use of benthos
data has proven to be a reliable monitoring tool, as benthic macroinvertebrates are sensitive to
subtle changes in water quality. Since macroinvertebrates have life cycles of six months to over
one year, the effects of short-term pollution (such as a spill) will generally not be overcome until
the following generation appears. The benthic community also integrates the effects of a wide
array of potential pollutant mixtures.
Criteria have been developed to assign a bioclassification to each benthic sample based on the
number of different species present in the pollution intolerant groups of Ephemeroptera
(Mayflies), Plecoptera (Stoneflies) and Trichoptera (Caddisflies), commonly referred to as EPTs,
and a Biotic Index value, which gives an indication of overall community pollution tolerance.
Different benthic macroinvertebrate criteria have been developed for different ecoregions
(mountains, piedmont and coastal plain) within North Carolina. Bioclassifications fall into five
categories ranging from Poor to Excellent.
Extensive evaluation of swamp streams across eastern North Carolina suggests that current
coastal plain criteria are not appropriate for assessing the condition of water quality in these
special systems. Swamp streams are characterized by slower flow, lower dissolved oxygen,
lower pH, and sometimes very complex braided channels and dark-colored water. DWQ is
working to refine biological criteria that may be used in the future to assign bioclassifications to
these streams. Refer to Chapter 4 of this section for more detailed information.
Overview of Benthic Macroinvertebrate Data
Appendix II lists all the benthic macroinvertebrate collections in the Roanoke River basin
between 1983 and 1999, giving site location, collection date, taxa richness, biotic index values
DWQ monitoring programs for the
Roanoke River Basin include:
• benthic macroinvertebrates
(Section 3.3.1)
• fish assessments
(Section 3.3.2)
• aquatic toxicity monitoring
(Section 3.3.3)
• lakes assessment
(Section 3.3.4)
• ambient monitoring system
(Section 3.3.5)
Section A: Chapter 3 – Summary of Water Quality Information for the Roanoke River Basin 50
and bioclassifications. Benthic macroinvertebrates have been collected at 79 sites in the
Roanoke River basin since 1983. Table A-21 lists the most recent ratings since 1983, by
subbasin, for all 79 benthos sites. Most of the streams listed as "Not Rated" are swamp streams
in subbasins 03-02-08, 03-02-09 and 03-02-10. Benthos sampling may slightly overestimate the
proportion of Fair and Poor sites, as DWQ special studies often have the greatest sampling
intensity (number of sites/stream) in areas where it is believed that water quality problems exist.
Table A-21 Summary of Bioclassifications for All Freshwater Benthic Macroinvertebrate
Sites (using the most recent rating for each site) in the Roanoke River Basin
Subbasin Excellent Good Good-Fair Fair Poor Not Rated Total
03-02-01 3 7 7 2 1 0 20
03-02-02 0 2 3 0 0 0 5
03-02-03 1 4 0 2 0 0 7
03-02-04 0 1 1 0 0 0 2
03-02-05 0 0 0 2 0 0 2
03-02-06 0 0 2 3 0 2 7
03-02-07 0 0 1 1 0 0 2
03-02-08 0 3 0 3 0 5 11
03-02-09 0 0 2 0 0 10 12
03-02-10 0 0 0 0 0 8 8
Total (#) 4 17 16 13 1 28 79
Total (%) 5% 22% 20% 16% 2% 35%100%
Sampling was hampered by extremes in streamflows in 1999. Many streams ceased flowing
during the summer drought, while other sites could not be sampled because of high flow events.
Therefore, only 35 sites were sampled during 1999 basinwide surveys or special studies. For the
1999 collections, Figure A-17 presents the following bioclassifications: Excellent – 0, Good – 6
(17%), Good-Fair – 5 (14%), Fair – 7 (20%), Poor – 0, Not Rated – 17 (49%).
Long-term trends (>5 years of data) in water quality were evaluated at six sites in the Roanoke
River basin. None of the sites showed a decline in water quality. One site showed positive
changes related to improvements in wastewater treatment. Subbasin chapters in Section B
contain more specific information regarding these streams.
Section A: Chapter 3 – Summary of Water Quality Information for the Roanoke River Basin 51
1999 Benthic Sampling Results
Good
17%Not Rated
49%
Fair
20%
Good-Fair
14%
Figure A-17 Bioclassifications for 35 Roanoke River Basin Benthic Macroinvertebrate Sites
Sampled by DWQ in 1999
3.3.2 Fish Assessments
Historical studies of fish communities in the Roanoke River basin were conducted primarily by
the North Carolina Wildlife Resources Commission (NCWRC) in the 1960s and late 1970s.
Approximately 102 species have been collected from the Roanoke River basin in North Carolina.
Several streams were sampled by DWQ during the last basinwide planning cycle (1994), and two
samples were collected in 1999. Scores are assigned to these samples using the North Carolina
Index of Biotic Integrity (NCIBI). The NCIBI uses a cumulative assessment of twelve
parameters or metrics. 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.
Appendix II contains more information regarding the NCIBI.
During the late 1990s, application of the NCIBI has been restricted to wadeable streams that can
be sampled by a crew of 2-4 persons using backpack electrofishers and following the DWQ
Standard Operating Procedures (NCDEHNR, 1997). 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 other
biological monitoring programs, many years of reference site data will be needed before solid
criteria can be developed to evaluate biological integrity of large streams and rivers using the fish
community assessment. Refer to Chapter 4 of this section for further information.
Overview of Fish Community Data
Appendix II lists all of the fish community collections in the Roanoke River basin between 1990
and 1999, giving site location, collection date and NCIBI rating. Fish community samples have
been collected at 16 sites in the Roanoke River basin since 1990. Table A-22 lists the most
recent ratings since 1990, by subbasin, for all fish community sites.
Section A: Chapter 3 – Summary of Water Quality Information for the Roanoke River Basin 52
Table A-22 Summary of NCIBI Categories for All Freshwater Fish Community Sites (using
the most recent rating for each site) in the Roanoke River Basin
Subbasin Excellent Good Good-Fair Fair Poor Not Rated Total
03-02-01 0 0 0 0 0 0 0
03-02-02 0 1 0 0 0 0 1
03-02-03 1 0 0 0 0 0 1
03-02-04 0 2 1 0 0 0 3
03-02-05 0 0 1 0 0 0 1
03-02-06 1 1 1 0 0 0 3
03-02-07 0 0 2 0 0 0 2
03-02-08 0 1 1 0 0 2 4
03-02-09 0 0 0 0 0 0 0
03-02-10 0 0 0 0 0 1 1
Total (#) 2 5 6 0 0 3 16
Total (%) 13% 31% 37% 0% 0% 19%100%
No basinwide fish community surveys were conducted during 1999 because of ongoing special
studies and additional reference site sampling. Only 2 sites were sampled in 1999: Grassy Creek
received a Good NCIBI score and Island Creek received an Excellent score.
Roanoke River Basin Fish Kills
DWQ has only systematically tracked reported fish kill events across the state since 1996. From
1994 to 1999, DWQ field investigators reported five fish kill events in the Roanoke River basin.
Fish kills occurred on the Roanoke River from Roanoke Rapids to Jamesville and along the
Cashie River near Windsor and Sans Souci. Mortality estimates ranged from 30 to more than
10,000 fish per event.
Two of these fish kills were extensive and occurred in the Roanoke River between July 25 and
August 2, 1995 as a result of operations at the Roanoke Rapids dam. The first kill occurred
directly below the dam after spillway gates were closed leaving fish stranded in isolated pools
where water temperature increased rapidly. The second kill began after water release rates from
the dam were rapidly curtailed causing waters which had inundated thousands of acres of
wetlands adjacent the Roanoke River, and which had become anoxic, to empty into the river.
This fish kill occurred over approximately 76 miles and killed an estimated 7,000 striped bass as
well as approximately 16,000 other species. Dissolved oxygen in the kill area ranged from 0.4 to
2.0 mg/l (Kornegay and Jones, 1995).
The magnitude of these events led Dominion (formerly North Carolina Power) to implement, in
cooperation with the NC Wildlife Resources Commission and the US Army Corps of Engineers,
a plan to incrementally "step down" flood control flow reductions (refer to Part 2.9.4 of this
Section A: Chapter 3 – Summary of Water Quality Information for the Roanoke River Basin 53
section for more information). Since the plan was put into effect, no additional fish kills have
been reported related to reduction of water releases. Fish kills were also reported following
Hurricane Fran and Hurricane Bonnie in 1996 and 1998, respectively.
Overview of Fish Tissue Sampling
Fish tissue surveys were conducted by DWQ at eight stations within the basin from 1994 to
1999. These surveys were conducted as part of special mercury contamination assessments in
the eastern part of the state and during routine basinwide assessments.
The majority of fish tissue samples collected from the Roanoke River basin in 1994 and 1999
contained metal and organic contaminants at undetectable levels or at levels less than the EPA,
Food and Drug Administration, and State of North Carolina consumption criteria. Figure A-18
shows the number of fish tissue samples that exceeded one or more of these consumption criteria.
Only six sites are represented on the figure because none of the samples collected from the Dan
River at Eden or from Lake Gaston exceeded any consumption criteria. More detailed
information regarding these sampling events and streams can be found in the appropriate
subbasin chapter in Section B.
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Figure A-18 Fish Tissue Samples Exceeding Consumption Criteria at Six Sites Sampled by
DWQ in 1994 and 1999
Elevated mercury concentrations were most often detected in largemouth bass and bowfin.
These two species are at the top of the food chain and are most often associated with mercury
bioaccumulation in fish tissue in North Carolina. More than 50 percent of samples collected
from the Roanoke River at Williamston and the Cashie River at Windsor contained mercury
concentrations exceeding the state criteria. Presently, the only consumption advisory for
mercury-contaminated fish in the Roanoke River basin is the statewide advisory for bowfin.
Section A: Chapter 3 – Summary of Water Quality Information for the Roanoke River Basin 54
No samples from the above referenced eight stations contained concentrations greater than
consumption criteria of any other metals of concern (arsenic, cadmium, chromium, copper, lead,
nickel, selenium and zinc). Samples collected by Duke Power Company and Carolina Power &
Light Company in Belews Lake and Hyco Reservoir, respectively, have shown high
concentrations of selenium. However, contamination levels have declined in recent years. More
information regarding causes and sources of the selenium, as well as recommended management
strategies for these waters, can be found in Section B.
Weyerhaeuser Company monitors dioxin levels in fish tissue in the lower Roanoke River and
Welch Creek. Fish consumption advisories for almost all species of fish due to dioxin
contamination are in effect in these waters, as well as the western portion of Albemarle Sound,
although levels of dioxin have also been declining in recent years. Refer to Chapter 9 of Section
B for more information regarding these waters.
3.3.3 Aquatic Toxicity Monitoring
Acute and/or chronic toxicity tests are used to determine toxicity of discharges to sensitive
aquatic species (usually fathead minnows or the water flea, Ceriodaphnia dubia). Results of
these tests have been shown by several researchers to be predictive of discharge effects on
receiving stream populations. Many facilities are required to monitor whole effluent toxicity by
their NPDES permit or by administrative letter. Other facilities may be tested by DWQ’s
Aquatic Toxicology laboratory.
The Aquatic Toxicology Unit maintains a compliance summary (Figure A-19) for all facilities
required to perform tests and provides a monthly update of this information to regional offices
and DWQ administration. Ambient toxicity tests can be used to evaluate stream water quality
relative to other stream sites and/or a point source discharge.
0
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1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998
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Figure A-19 Summary of Compliance with Aquatic Toxicity Tests in the Roanoke River Basin
Section A: Chapter 3 – Summary of Water Quality Information for the Roanoke River Basin 55
Twenty-nine NPDES permits in the Roanoke River basin currently require whole effluent
toxicity (WET) testing. Twenty-seven permits have a WET limit; the other two facilities have
episodic discharges and their permits specify monitoring but with no limit.
The number of facilities required to monitor whole effluent toxicity has increased steadily since
1987, the first year that whole effluent toxicity limits were written into permits in North
Carolina. The compliance rate has risen as well. Since 1993, the compliance rate has stabilized
at approximately 90-95 percent. Facilities with toxicity problems during the most recent two-
year review period are discussed in the subbasin chapters in Section B
3.3.4 Lakes Assessment Program
Eleven lakes in the Roanoke River basin were sampled as part of the Lakes Assessment Program
in summer of 1999. These data are used to determine the trophic state of each lake, a relative
measure of nutrient enrichment and biological productivity. Five lakes (Hanging Rock, Belews
Lake, Hyco Lake, Mayo Reservoir and Lake Gaston) exhibited low biological productivity. The
North Carolina portion of John H. Kerr Reservoir and Roanoke Rapids Lake demonstrated
moderate biological productivity. The remaining four lakes (Kernersville Reservoir, Farmer
Lake, Lake Roxboro and Roxboro Lake) were found to be very biologically productive. Lakes
for which one or more uses are impaired are listed in Part 3.5.3 of this section (Table A-31) and
are discussed in the appropriate subbasin chapter in Section B.
3.3.5 Ambient Monitoring System
The Ambient Monitoring System (AMS) is a network of stream, lake and estuarine sample
stations strategically located for the collection of physical and chemical water quality data.
North Carolina has 21 stations in the Roanoke River basin listed in Table A-23 and shown on
individual subbasin maps in Section B. These stations are sampled monthly for 27 parameters.
Overall, measurements of water quality parameters in the Roanoke River basin showed few
temporal patterns. An exception is the site located on Nutbush Creek, where water quality
improved greatly during the mid-1980s as improvements to the Town of Henderson’s WWTP
were put into place. At other sites, distinct spatial differences occurred depending upon whether
or not the sites were located upstream or downstream of wastewater dischargers.
Fecal coliform bacteria are widely used as an indicator of the potential presence of pathogens
typically associated with the intestinal tract of warm-blooded animals. The water quality
standard for fecal coliform bacteria is based on a geometric mean of 200 colonies/100ml. Fecal
coliform bacteria concentrations, represented by geometric means, showed few temporal
patterns. The only ambient monitoring station with a geometric mean greater than 200
colonies/100 ml for this five-year assessment period was Marlowe Creek (N4400000). Most
stations in the basin (67 percent) had geometric means of less than 100 colonies/100ml.
Section A: Chapter 3 – Summary of Water Quality Information for the Roanoke River Basin 56
Table A-23 Ambient Monitoring System Stations within the Roanoke River Basin
Subbasin/
Station code Station County Classification*
03-02-01
N0150000 Dan River at NC Hwy 704, near Francisco Stokes C Tr
03-02-02
N1400000 Mayo River at SR 1358, near Price Rockingham WS-IV
03-02-03
N2300000 Dan River at SR 2150, near Wentworth Rockingham WS-IV
N2450000 Smith River at NC Hwy 14, at Eden Rockingham WS-IV
N3000000 Dan River at SR 1716, near Mayfield Rockingham C
03-02-04
N3500000 Dan River at NC Hwy 62 at NC-VA state line Caswell C
03-02-05
N4110000 Hyco Creek at US Hwy 158, near Leasburg Caswell C
N4250000 Hyco River below afterbay dam, near McGhees Mill Person C
N4400000 Marlowe Creek at SR 1322, near Woodsdale Person C
N4510000 Hyco River at US Hwy 501, near Denniston, VA Halifax Virginia
N4590000 Mayo Creek at SR 1501, near Bethel Hill Person C
03-02-06
N5000000 Nutbush Creek at SR 1317, near Henderson Vance C
03-02-07
N6400000 Smith Creek at US 1, near Paschall Warren C
03-02-08
N7300000 Roanoke River at Roanoke Rapids Halifax C
N8200000 Roanoke River near Scotland Neck Halifax C
N8300000 Roanoke River at NC Hwy 11 Martin C
03-02-09
N8550000 Roanoke River at Williamston Martin C
N9250000 Roanoke River near Plymouth Martin C Sw
N9600000 Roanoke River at Sans Souci Bertie C Sw
N9700000 Albemarle Sound (Batchelor Bay) near Black Walnut Bertie B Sw
03-02-10
N8950000 Cashie River at SR 1219, near Lewiston Bertie C Sw
* An index for DWQ freshwater classifications can be found in Part 3.2 of this section (Table A-20).
Elevated turbidity measurements were observed often in streams in the Dan River subbasins over
the past five years. The turbidity standard for trout waters (10 NTU) was exceeded in 35 percent
of 54 samples collected from the upper Dan River (N0150000) near Fransico. The turbidity
standard (50 NTU) was exceeded at the Dan River near Wentworth station (N2300000) in 18
percent of 55 samples between 1995 and 1999. Concentrations in this segment of the Dan River
ranged from 2.6 to 200 NTU, compared with 1.4 to 90 NTU near Francisco upstream. The
turbidity water quality standard was only exceeded in 9 percent of samples at the downstream
station near Mayfield (N3000000). More information regarding causes and sources of turbidity,
as well as recommended management strategies for the Dan River, can be found in Section B.
Section A: Chapter 3 – Summary of Water Quality Information for the Roanoke River Basin 57
Figure A-20 depicts nearly 20 years of dissolved oxygen data collected from DWQ Ambient
Monitoring Stations in the Roanoke River basin. (Appendix V contains an explanation of box
plots.) Dissolved oxygen (DO) concentrations were low at the Smith Creek station in the Dan
River watershed. Approximately 25 percent of measurements were less than the 5.0 mg/l water
quality standard between September 1994 and August 1999. The stream at this sampling
location is slow moving, a factor which could contribute to these sample results. In the eastern
portion of the basin, the Cashie River exhibited very low DO concentrations; however, the
monitoring site is located in swamp waters where DO is naturally lower.
Figure A-20 Dissolved Oxygen Concentrations at Ambient Monitoring Stations in the
Roanoke River Basin (1980-1999)
Dissolved oxygen fell below the water quality standard in less than seven percent of samples
collected between September 1994 and August 1999 from any station on the Roanoke River
mainstem. DWQ Ambient Monitoring System data showed no significant difference between
Section A: Chapter 3 – Summary of Water Quality Information for the Roanoke River Basin 58
DO data collected above (N9250000) and below (N9600000) Plymouth over the same five-year
period.
Copper and iron were the only two metals that often exceed their action levels. Iron is a common
element in clay soils; therefore, elevated concentrations may reflect the geochemistry of the
watershed. In general, elevated concentrations of copper were found at sites located downstream
of wastewater discharges.
3.4 Other Water Quality Research
North Carolina actively solicits "existing and
readily available" data and information for each
basin as part of the basinwide planning process.
Data meeting DWQ quality assurance objectives
are used in making use support determinations.
Data and information indicating possible water
quality problems are investigated further. Both
quantitative and qualitative information are
accepted during the solicitation period. High levels
of confidence must be present in order for outside
quantitative information to carry the same weight as
information collected from within DWQ. This is
particularly the case when considering waters for
the §303(d) list. Methodology for soliciting and
evaluating outside data is presented in North
Carolina’s Draft 2000 § 303(d) List (DENR-DWQ,
October 2000). The next data solicitation period
for the Roanoke River is planned for fall 2003.
Continuous monitoring data (dissolved oxygen and temperature) were submitted by the US Fish
and Wildlife Service from five US Geological Survey stations on the Roanoke River: Halifax
(station #0208062765); Oak City (station #02081022); Grabtown (station #0208102855);
Jamesville (station #02081094); and Westover (station #020811450). Data are collected from
each of these stations at 15-minute intervals. Data summarized below are from January 1, 1998
(when the stations were put into operation) through August 31, 1999. August 31, 1999 is the end
of the five-year window for data collected during this five-year planning cycle and reported in
this plan.
The dissolved oxygen (DO) water quality standard for Class C waters is "not less than a daily
average of 5.0 mg/l with a minimum instantaneous value of not less than 4.0 mg/l". Swamp
waters (Class C Sw) "may have lower values if caused by natural conditions" (DENR, August
2000). Table A-24 presents the number of samples representing daily averages and the number
and percent of samples less than the 5.0 mg/l DO standard for each monitoring station. Table A-
25 presents the number of samples representing instantaneous measurements and the number and
percent of samples less than the 4.0 mg/l DO standard for each monitoring station.
DWQ data solicitation includes
the following:
• Information, letters and photographs
regarding the uses of surface waters for
boating, drinking water, swimming,
aesthetics and fishing.
• Raw data submitted electronically and
accompanied by documentation of
quality assurance methods used to collect
and analyze the samples. Maps showing
sampling locations must also be included.
• Summary reports and memos, including
distribution statistics and accompanied
by documentation of quality assurance
methods used to collect and analyze the
data.
• Contact information must accompany all
data and information submitted.
Section A: Chapter 3 – Summary of Water Quality Information for the Roanoke River Basin 59
Table A-24 USGS Continuous Monitoring Station Daily Average Dissolved Oxygen (DO)
Data Summary for the Roanoke River Basin (1/98-8/99)
USGS Station
Name
Stream
Class
Water
Quality
Standard
Number of
Samples
Number of
Samples DO
<5.0 mg/l
% of total
Samples DO
<5.0 mg/l
Halifax C 5.0 mg/l 512 0 --
Oak City C 5.0 mg/l 389 0 --
Grabtown C 5.0 mg/l 494 0 --
Jamesville C 5.0 mg/l 524 30 5.7%
Westover C Sw 5.0 mg/l* 501 107 21.4%
* Swamp waters may have lower values if caused by natural conditions.
Table A-25 USGS Continuous Monitoring Station Instantaneous Dissolved Oxygen (DO)
Data Summary for the Roanoke River Basin (1/98-8/99)
USGS Station
Name
Stream
Class
Water
Quality
Standard
Number of
Samples
Number of
Samples DO
<4.0 mg/l
% of total
Samples DO
<4.0 mg/l
Halifax C 4.0 mg/l 48,790 0 --
Oak City C 4.0 mg/l 36,852 0 --
Grabtown C 4.0 mg/l 47,068 0 --
Jamesville C 4.0 mg/l 49,966 561 1.1%
Westover C Sw 4.0 mg/l* 47,575 5,077 10.7%
* Swamp waters may have lower values if caused by natural conditions.
Although, according to a strict interpretation, the data presented above show numerous violations
of the water quality standards for dissolved oxygen at the Jamesville monitoring station, this
station is located a short distance upstream of the boundary between the Class C and Class C Sw
portions of the Roanoke River. It is possible that some "swamp stream" characteristics are being
observed at this location.
Additional DWQ analyses show that an increase in temperature does not always accompany a
decrease in DO at the Oak City, Grabtown and Jamesville stations. Therefore, there are factors
other than temperature influencing DO concentrations at these stations. Refer to Chapter 4 of
this section for a discussion of studies designed to provide further information about dissolved
oxygen in the lower Roanoke River.
Water quality monitoring data for Nutbush Creek and the Nutbush Creek Arm of Kerr Reservoir
were submitted by the City of Henderson in hardcopy form only. Unfortunately, due to staff
time constraints, DWQ is unable to use raw data that is not submitted electronically.
Section A: Chapter 3 – Summary of Water Quality Information for the Roanoke River Basin 60
3.5 Use Support Summary
3.5.1 Introduction to Use Support
Waters are classified according to their best intended uses. Determining how well a water
supports its uses (use support status) is an important method of interpreting water quality data
and assessing water quality. Surface waters are rated fully supporting (FS), partially supporting
(PS) or not supporting (NS). The terms refer to whether the classified uses of the water (such as
water supply, aquatic life protection and recreation) are being met.
For example, waters classified for fishing and secondary
contact recreation (Class C for freshwater) are rated as fully
supporting if data used to determine use support did not
exceed specific criteria. However, if these criteria were
exceeded, then the waters would be rated as PS or NS,
depending on the degree of degradation. Waters rated PS or
NS are considered to be impaired. Waters lacking data, or
having inconclusive data, are listed as not rated (NR).
Historically, the non-impaired category was subdivided into
fully supporting and fully supporting but threatened (ST). ST
was used to identify waters that were fully supporting but had
some notable water quality concerns and could represent
constant, degrading or improving conditions. North
Carolina’s past use of ST was very different from that of the
US Environmental Protection Agency (EPA), which uses it to identify waters that demonstrate
declining water quality (EPA Guidelines for Preparation of the Comprehensive State Water
Quality Assessments [305(b) Reports] and Electronic Updates, 1997). Given the difference
between the EPA and North Carolina definitions of ST and the resulting confusion that arises
from this difference, North Carolina no longer subdivides the non-impaired category. However,
these waters and the specific water quality concerns remain identified in the subbasin chapters in
Section B so that data, management and the need to address the identified concerns are not lost.
Beginning in 2000 with the Roanoke River basin, an approach to assess ecosystem health and
human health risk is applied to use support categories. Six categories are used to assess this
approach: aquatic life and secondary recreation, fish consumption, shellfish harvesting, primary
recreation, water supply and "other" uses. Each of these categories relates to the primary
classifications applied to NC rivers and streams. A single water could have more than one use
support rating corresponding to one or more of the multiple use support categories, as shown in
Table A-31. For many waters, a use support category will not be applicable (NA) to the best use
classification of that water (e.g., drinking water supply is not the best use of a Class C water).
This method of determining use support differs from that done prior to 2000; in that, there is no
longer an overall use support rating for a water. For more detailed information regarding use
support methodology, refer to Appendix III.
Use support ratings for
surface waters:
• fully supporting (FS)
• partially supporting (PS)
• not supporting (NS)
• not rated (NR)
Impaired waters categories:
• partially supporting
• not supporting
Section A: Chapter 3 – Summary of Water Quality Information for the Roanoke River Basin 61
3.5.2 Comparison of Use Support Ratings to Streams on the Section 303(d) List
Section 303(d) of the Clean Water Act requires states to identify waters not meeting standards.
EPA must then provide review and approval of the listed waters. A list of waters not meeting
standards is submitted to EPA biennially. Waters placed on this list, termed the §303(d) list,
require the establishment of total maximum daily loads (TMDLs) intended to guide the
restoration of water quality. See Appendix IV for a description of §303(d) listing methodology.
Waters are placed on North Carolina’s §303(d) list primarily due to a partially or not supporting
use support rating. These use support ratings are based on biological and chemical data and, for
some categories, human health advisories. When the state water quality standard is exceeded,
then this constituent is listed as the problem parameter. TMDLs must be developed for problem
parameters on the §303(d) list. Other strategies may be implemented to restore water quality;
however, the waterbody must remain on the §303(d) list until improvement has been realized
based on either biological bioclassifications or water quality standards.
The §303(d) list and accompanying data are updated as the basinwide plans are revised. In some
cases, the new data will demonstrate water quality improvement and waters may receive a better
use support rating. These waters may be removed from the §303(d) list since water quality
improvement has been attained. In other cases, the new data will show a stable or decreasing
trend in overall water quality resulting in the same, or lower, use support rating. Attention
remains focused on these waters until water quality standards are being met.
3.5.3 Use Support Ratings for the Roanoke River Basin
Aquatic Life/Secondary Recreation
The aquatic life/secondary recreation use support category is applied to all waters in North
Carolina. Therefore, this category is applied to the total number of stream miles (2213.0) in the
North Carolina portion of the Roanoke River basin. Table A-25 presents use support ratings by
subbasin for both monitored and evaluated streams in the aquatic life/secondary recreation
category. A basinwide summary of current aquatic life/secondary recreation use support ratings
is presented in Table A-26.
Approximately 29 percent of stream miles (638) were monitored for the protection of aquatic life
and secondary recreation by DWQ during this basinwide planning cycle. All waters rated
impaired in the aquatic life/secondary recreation use support category were monitored within the
past five years. Impaired waters accounted for 2.6 percent of the total stream miles and 8.9
percent of monitored stream miles.
Section A: Chapter 3 – Summary of Water Quality Information for the Roanoke River Basin 62
Table A-25 Aquatic Life/Secondary Recreation Use Support Ratings for Monitored and
Evaluated Waters Listed by Subbasin in Miles (1995-1999)
Subbasin Fully
Supporting
Partially
Supporting
Not
Supporting
Not
Rated Total
03-02-01 276.5 0 8.0 148.9 433.4
03-02-02 76.4 0 0 55.6 132.0
03-02-03 154.6 19.5 0 68.8 242.9
03-02-04 112.0 0 0 39.6 151.6
03-02-05 84.8 10.8 0 99.3 194.9
03-02-06 127.0 4.6 0 53.0 184.6
03-02-07 41.7 10.4 0 49.4 101.5
03-02-08 167.9 3.4 0 180.6 351.9
03-02-09 72.8 0 0 198.3 271.1
03-02-10 0 0 0 149.1 149.1
TOTAL 1113.7 48.7 8.0 1042.6 2213.0
Percent 50.3% 2.2% 0.4% 47.1% 100%
Table A-26 Aquatic Life/Secondary Recreation Use Support Summary Information for Waters
in the Roanoke River Basin (1999)
Monitored and
Evaluated Streams*
Monitored
Streams Only**Aquatic Life/Secondary Recreation
Use Support Ratings Miles % Miles %
Fully Supporting 1113.7 50.3% 357.0 56.0%
Impaired 56.7 2.6% 56.7 8.9%
Partially Supporting 48.7 2.2% 48.7 7.6%
Not Supporting 8.0 0.4% 8.0 1.3%
Not Rated 1042.6 47.1% 223.9 35.1%
TOTAL 2213.0 637.6
* = Percent based on total of all streams, both monitored and evaluated. ** = Percent based on total of all monitored streams.
Fish Consumption
Like the aquatic life/secondary recreation use support category, the fish consumption use support
category is also applied to all waters in the state. Approximately 14 percent of stream miles
(308.0 miles) in the Roanoke River basin were monitored for the fish consumption category
during this basinwide cycle. Fish consumption use support ratings are based on fish
consumption advisories issued by the NC Department of Health and Human Services (DHHS).
Currently, there is a statewide advisory limiting consumption of bowfin due to elevated mercury
concentrations. Because of this advisory, all waters in the state are considered partially
supporting the fish consumption use. However, samples collected by DWQ in 1999 from some
waters in the basin, including the Dan River, Kerr Reservoir and Lake Gaston (where bowfin are
Section A: Chapter 3 – Summary of Water Quality Information for the Roanoke River Basin 63
not typically found), revealed concentrations of metals and PCBs below federal and state
consumption criteria.
Table A-27 presents use support ratings by subbasin for monitored streams in the fish
consumption use support category. A basinwide summary of current fish consumption use
support ratings is presented in Table A-28.
Table A-27 Fish Consumption Use Support Ratings for Monitored Waters Listed by Subbasin
in Miles (1995-1999)
Subbasin Fully
Supporting
Partially
Supporting
Not
Supporting
Not
Rated Total
03-02-011,2 0 55.8 0 0 55.8
03-02-021 09.30 09.3
03-02-031 0 14.8 0 0 14.8
03-02-041 07.50 07.5
03-02-053 00.20 00.2
03-02-064 05.10 05.1
03-02-074 05.40 05.4
03-02-08 0 123.7 0 0 123.7
03-02-09 0 25.3 13.3 0 38.6
03-02-10 0 47.6 0 0 47.6
TOTAL 0 294.7 13.3 0 308.0
Percent 0% 95.7% 4.3% 0% 100%
1 Analysis of fish tissue samples, collected by DWQ in 1999 from the Dan River, did not reveal elevated concentrations of
any metals, including mercury, in any species of fish collected.
2 Belews Lake (4,030 acres) is also included in the monitored waters in this subbasin.
3 Hyco Lake (3,750 acres) is also included in the monitored waters in this subbasin.
4 Analysis of fish tissues samples, collected by DWQ in 1999 from Kerr Reservoir and Lake Gaston, did not reveal elevated
concentrations of any metals or PCBs in any species of fish collected.
Table A-28 Fish Consumption Use Support Summary Information for Waters in the Roanoke
River Basin (1999)
Monitored and
Evaluated Streams*
Monitored
Streams Only**
Fish Consumption
Use Support Ratings
Miles % Miles %
Fully Supporting 0.0 0.0
Impaired 2213.0 100% 308.0 100%
Partially Supporting 2199.7 99.4% 294.7 95.7%
Not Supporting 13.3 0.6% 13.3 4.3%
Not Rated 0.0 0.0
TOTAL 2213.0 308.0
* = Percent based on total of all streams, both monitored and evaluated. ** = Percent based on total of all monitored streams.
Section A: Chapter 3 – Summary of Water Quality Information for the Roanoke River Basin 64
Primary Recreation
There are 120.2 stream miles currently classified for primary recreation in the Roanoke River
basin. Approximately 15 percent were monitored by DWQ over the past five years; all are fully
supporting the primary recreation use. Monitored waters include Hyco Lake, Kerr Reservoir and
Lake Gaston. A basinwide summary of current primary recreation use support ratings is
presented in Table A-29.
Table A-29 Primary Recreation Use Support Summary Information for Waters in the Roanoke
River Basin (1999)
Monitored and
Evaluated Streams*
Monitored
Streams Only**
Primary Recreation
Use Support Ratings
Miles % Miles %
Fully Supporting 18.5 15.4% 18.5 100%
Impaired 0.0 0.0
Not Rated 101.7 84.6% 0.0
TOTAL 120.2 18.5
* = Percent based on total of all streams, both monitored and evaluated. ** = Percent based on total of all monitored streams.
Water Supply
There are 270.4 stream miles currently classified for water supply in the Roanoke River basin.
All were monitored within the past five years; all are fully supporting the water supply use.
Monitored waters include Belews Lake, Hyco Lake, Kerr Reservoir and Lake Gaston. A
basinwide summary of current water supply use support ratings is presented in Table A-30.
Table A-30 Water Supply Use Support Summary Information for Waters in the Roanoke
River Basin (1999)
Monitored and
Evaluated Streams*
Monitored
Streams Only**Water Supply
Use Support Ratings Miles % Miles %
Fully Supporting 270.4 100% 270.4 100%
Impaired 0.0 0.0
Not Rated 0.0 0.0
TOTAL 270.4 270.4
* = Percent based on total of all streams, both monitored and evaluated. ** = Percent based on total of all monitored streams.
Impaired Waters
Table A-31 presents impaired waters (in all categories), listed by subbasin, in the Roanoke River
basin that were monitored by DWQ within the last five years. Ratings for each applicable use
support category are shown, even though only one use may be impaired. Impaired ratings are
shown in bold followed by the number of miles (streams and rivers) or acres (lakes) where the
Section A: Chapter 3 – Summary of Water Quality Information for the Roanoke River Basin 65
corresponding use is impaired. Descriptions of impaired segments, as well as problem
parameters, are outlined in Appendix III. Management strategies for each water are discussed in
detail in the appropriate subbasin chapter.
Color maps showing current use support ratings for the Roanoke River basin are presented in
Figures A-21 and A-22. Only waters where fish tissue has been monitored during this basinwide
cycle are shown as impaired for fish consumption on the maps. When use support ratings have
been assigned to more than one category for a particular water, the rating that represents the most
severe impairment is shown on the map (e.g., Hyco Lake is fully supporting aquatic
life/secondary recreation, but is partially supporting fish consumption. The lake is shown on
Figure A-21 as partially supporting.)
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9