2001 Roanoke Sec B Chap 9

Section B: Chapter 9 - Roanoke River Subbasin 03-02-09 146
Chapter 9 -
Roanoke River Subbasin 03-02-09
Includes the lowest portion of the Roanoke River and tributaries
9.1 Water Quality Overview
This subbasin contains the lower 83 miles of the Roanoke
River and tributaries including Conoho, Indian, Hardison
Mill, Welch and Conaby Creeks. Municipalities include
Hamilton, Williamston, Jamesville and Plymouth. A map
of this subbasin including water quality sampling
locations is presented in Figure B-9.
Bioclassifications for sample sites in this subbasin are
presented in Table B-23. Use support ratings for each
applicable category in this subbasin are summarized in
Table B-24. Refer to Appendix III for a complete listing
of monitored waters and further information about use
support ratings.
This subbasin is located entirely within the coastal plain
of North Carolina. Most of the land is forested (71
percent), but a significant amount is also used for
agriculture (25 percent).
The lower Roanoke River is bordered by extensive floodplain forests. These "backswamps" are
inundated during high flows when the river is full. Then, when the river level drops, water
returns to the main channel through only a few connections, called "guts". Through the collected
efforts of The Nature Conservancy, the US Fish and Wildlife Service, and the NC Wildlife
Resources Commission, more than 34,000 acres of the floodplain have been brought into
conservation ownership. With an additional 21,000 acres of Georgia-Pacific timberland under
conservation management, an almost continuous corridor stretching from Hamilton to the Sound
has been preserved (see Section C for more information).
There are nine NPDES permitted dischargers in the subbasin. The largest discharge is 82.5
MGD from Weyerhaeuser Company. Others include the Williamston WWTP and the Plymouth
WWTP. All of three these discharges flow directly into the Roanoke River. The only facility in
significant noncompliance during this review period was the Williamston WWTP. Four facilities
are required to perform toxicity tests on their effluent. In the past, Liberty Fabrics has had the
most problems, failing 42 percent of its tests. However, in 1999, none of these facilities failed a
test.
Subbasin 03-02-09 at a Glance
Land and Water Area
Total area: 559 mi
2
Land area: 435 mi
2
Water area: 124 mi
2
Population Statistics
1990 Est. Pop.: 58,886 people
Pop. Density: 135 persons/mi
2
Land Cover (%)
Forest/Wetland: 71.5
Surface Water: 2.4
Urban: 0.6
Cultivated Crop: 24.8
Pasture/
Managed Herbaceous: 0.8
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Section B: Chapter 9 - Roanoke River Subbasin 03-02-09
Table B-23 DWQ Monitoring Locations and Benthic Macroinvertebrate Bioclassifications
(1999) for Roanoke River Subbasin 03-02-09
Site Stream County Location Bioclassification
Benthic Macroinvertebrates
B-1* Roanoke River Martin NC 125/903 Good-Fair
B-2* Roanoke River Martin Williamston Good-Fair
B-4* Conoho Creek Martin NC125/903 Not Rated
B-5 Conoho Creek Martin SR 1417 Not Rated
B-6 Hardison Mill Creek Martin NC 171 Not Rated
B-7 Hardison Mill Creek Martin SR 1528 Not Rated
B-8 Deep Run Swamp Martin NC 171 Not Rated
B-9 Welch Creek Martin SR 1522 Not Rated
B-10* Roanoke River Martin NC 45 Not Rated
Fish Tissue
FT-6 Roanoke River Martin Williamston N/A
FT-7 Roanoke River Martin Near Plymouth N/A
Ambient Monitoring
N8550000 Roanoke River Martin Williamston N/A
N9250000 Roanoke River Martin Above Plymouth N/A
N9600000 Roanoke River Bertie Below Plymouth N/A
N9700000 Albemarle Sound Bertie Batchelor Bay N/A
* Historical data are available; refer to Appendix II.
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
(as is currently done for other streams and rivers across the state). However, DWQ believes that
there has been insufficient sampling of reference swamp streams to assign these
bioclassifications and use them for use support determinations in the Roanoke River basin.
DWQ continues to work toward preparing these criteria for future use.
Based on benthic macroinvertebrate data, the biological community in the Roanoke River has
been assigned Good-Fair bioclassifications from the upper end of this subbasin to below
Williamston. These data represent a slight decline compared to communities observed upstream.
The lowest section of the river, above and below Plymouth, has experienced a mild temporary
estuarine influence in some years, but is still regarded as a lower coastal plain freshwater river.
Section B: Chapter 9 - Roanoke River Subbasin 03-02-09
Macroinvertebrate data from the river below Plymouth has suggested good water quality in this
section of the river, even though no bioclassification can be assigned.
All the tributaries in this subbasin are swampy and may experience periods of very little or no
flow. The lower portion of Conoho Creek was found to represent nearly natural swamp
conditions, while the upper portion of Conoho Creek, the upper and lower portions of Hardison
Mill Creek, and Welch Creek suggested water quality or habitat problems. The most severe
problems were observed in Deep Run Swamp, an area of intensive agricultural land use. These
streams are discussed in more detail in Part 9.5.1 and 9.5.2.
Water chemistry samples are collected monthly from sites on the Roanoke River near
Williamston and above and below Plymouth. These data have not indicated any major water
quality problems in these areas, with the exception of elevated ammonia nitrogen concentrations
below Plymouth (median = 0.075 mg/l).
Fish tissue samples were collected by DWQ from two sites on the Roanoke River in 1995 and
1999. Eight bowfin from the river near Williamston had mercury concentrations greater than
FDA consumption criteria in 1995. In 1999, 15 of 24 samples (63 percent) of bowfin,
largemouth bass and white catfish had mercury concentrations greater than EPA and FDA
criteria (0.6 and 1.0 µg/g, respectively). Mercury concentrations were somewhat lower near
Plymouth: four of seven (57 percent) bowfin collected in 1995 had high mercury concentrations.
In 1999, four (three largemouth bass and one chain pickerel) out of 22 samples (18 percent) had
concentrations which exceeded consumption criteria. The Roanoke River and Welch Creek are
impaired because of fish consumption advisories and are discussed in following sections.
For more detailed information on sampling and assessment of streams in this subbasin, refer to
the Basinwide Assessment Report - Roanoke River Basin (DENR-DWQ, May 2000), available
from DWQ Environmental Sciences Branch at http://www.esb.enr.state.nc.us/bar.html or by calling
[phone].
Table B-24 Use Support Ratings Summary (1999) for Monitored and Evaluated
1 Freshwater
Streams (miles) in Roanoke River Subbasin 03-02-09
Use Support
Category
FS PS NS NR Total
2
Aquatic Life/
Secondary Recreation
72.8 0 0 198.3 271.1
Fish Consumption 0 25.3 13.3 0 38.6
Primary Recreation 0 0 0 11.3 11.3
Water Supply 00000
1 For the fish consumption use support category, only monitored stream miles are presented.
2 Total stream miles assigned to each use support category in this subbasin. Column is not additive
because some stream miles are assigned to more than one category.
Section B: Chapter 9 - Roanoke River Subbasin 03-02-09
9.2 Status and Recommendations for Previously Impaired Waters
This section reviews use support and recommendations detailed in the 1996 basinwide plan,
reports status of progress, gives recommendations for the next five-year cycle, and outlines
current projects aimed at improving water quality for each water. The 1996 Roanoke River basin
plan identified two impaired streams and a portion of the Albemarle Sound in this subbasin.
These waters are discussed below.
9.2.1 Welch Creek (13.3 miles from source to Roanoke River)
Roanoke River (28.5 miles from Williamston to the Albemarle Sound)
Albemarle Sound (2,586 acres from Bull Bay to Harvey Point)
1996 Recommendation(s)
The 1996 basin plan listed Welch Creek and the Roanoke River from Williamston down to and
including the Albemarle Sound as partially supporting due to a fish consumption advisory for
dioxin. Weyerhaeuser Company operates a facility at the mouth of Welch Creek and originally it
discharged directly to the stream. In the 1980s, it was recognized that dioxin, a carcinogenic by-
product of the chlorine bleaching process, was accumulating in fish tissue. In 1988,
improvements were made and the discharge was relocated to the Roanoke River. Weyerhaeuser
is required by DWQ to provide extensive monitoring in the Roanoke River. The
recommendation was to review this data to monitor the decline of dioxin in fish tissue.
Status of Progress
These waters remain impaired (Welch Creek – not supporting; Roanoke River and Albemarle
Sound – partially supporting) because of fish consumption advisories for dioxin. No fish should
be consumed from Welch Creek. Data collected by Weyerhaeuser Company indicate a decline in
dioxin concentrations. Shellfish are not covered by this advisory.
2001 Recommendation(s)
DWQ, in cooperation with Weyerhaeuser Company, will continue to monitor the lower Roanoke
River and Welch Creek and will work closely with the Department of Health and Human
Services’ Division of Public Health to lift the advisory when there is no longer a risk to human
health from consumption of fish. For more information regarding fish consumption advisories,
call [phone] or visit the NC DHHS Division of Public Health website at
http://www.schs.state.nc.us/epi/fish/current.html.
9.3 Status and Recommendations for Newly Impaired Waters
The majority of the lower Roanoke River in North Carolina was rated as impaired based on fish
consumption advisories. This section outlines the potential causes and sources of impairment
and provides recommendations for improving water quality.
Section B: Chapter 9 - Roanoke River Subbasin 03-02-09
9.3.1 Roanoke River (138.7 miles from the Roanoke Rapids dam to the Albemarle Sound)
Current Status
The Roanoke River, from the Roanoke Rapids dam to the Albemarle Sound, is impaired because
of a statewide fish consumption advisory due to high levels of mercury in bowfin (blackfish).
Bowfin with levels of mercury that exceed consumption criteria were collected by DWQ in the
Roanoke River near Williamston and Plymouth in 1995 and 1999. Because of these advisories,
this portion of the river is only partially supporting the fish consumption use support category.
(Note: This is not a new advisory, but improved use support methodology now bases
impairment for the fish consumption use support category on fish consumption advisories.)
2001 Recommendation(s)
DWQ will continue to monitor fish tissue in the Roanoke River and will work to identify sources
of mercury. Given the global scale of mercury cycling, it may be difficult for DWQ to recognize
significant reductions of mercury in fish over the short-term. The NC Department of
Environment and Natural Resources (DENR) has established a Mercury Task Force that includes
staff from DWQ, Division of Air Quality, Hazardous Waste, Pollution Prevention and Wildlife
Resources. In addition, DWQ has established an internal Water Quality Section Work Group to
stay abreast of mercury issues. Section A, Part 4.8 provides more details about mercury.
9.4 Section 303(d) Listed Waters
Currently in this subbasin, there are no waters listed on the state’s year 2000 §303(d) list. The
Roanoke River and Welch Creek, along with all other waters in the basin, will be added to the
state’s §303(d) list of impaired waters in 2002 based on fish consumption advisories. Refer to
Appendix IV for more information on the state’s §303(d) list and listing requirements.
9.5 Other Issues and Recommendations
The surface waters discussed in this section are fully supporting designated uses (or not rated)
based on recent DWQ monitoring; however, data revealed some impacts to water quality.
Although no action is required for these streams, voluntary implementation of BMPs is
encouraged and continued monitoring is recommended. DWQ will notify local agencies of water
quality concerns regarding these waters and work with them to conduct further monitoring and to
locate sources of water quality protection funding. Nonpoint source program agency contacts are
listed in Appendix VI.
9.5.1 Hardison Mill Creek
Deep Run Swamp
As was mentioned previously, the benthic macroinvertebrate communities of these two streams
were sampled, but not rated by DWQ, in 1999 because of their swampy nature. However,
significantly less diverse aquatic communities were observed in these streams than in other
Roanoke River basin swamp stream communities. The headwaters of both streams are
extensively channelized leading to severe habitat degradation in several miles of stream in these
watersheds. Refer to Section A, Part 4.4 for further information and recommendations.