chapter 27 stressors

Chapter 27
Water Quality Stressors

27.1 Stressor Identification

27.1.1 Introduction and Overview

Water quality stressors are identified when impacts have been noted to biological (fish and
benthic) communities or water quality standards have been violated. Stressors apply to one or
more use support categories and may be identified for Impaired as well as Supporting waters
with noted impacts. Identifying stressors is difficult in many cases because direct measurements
of the stressor may be difficult or prohibitively expensive. DWQ staff use field observations
from sample sites, special studies and data from ambient monitoring stations as well as
information from other agencies and the public to identify potential water quality stressors. It is
important to identify stressors and potential sources of stressors so that water quality programs
can target limited resources to address water quality problems.

Stressors to recreation uses include the following pathogen indicators - fecal coliform bacteria,
escheria coli, and enterrococci. Stressors to shellfish harvesting are fecal coliform bacteria, and
stressors to fish consumption are mercury and any other substance that causes issuance of a fish
consumption advisory.
Most stressors to the biological community are complex groupings of many different stressors
that individually may not degrade water quality or aquatic habitat but together can severely
degrade aquatic life. Sources of stressors are most often associated with land use in a watershed
as well as the quality and quantity of any treated wastewater that may be entering a stream.
During naturally severe conditions such as droughts or floods, any individual stressor or group of
stressors may have more severe impacts to aquatic life than during normal climatic conditions.
The most common source of stressors is from altered watershed hydrology.
As discussed above, sources of stressors most often come from a watershed where the hydrology
is altered enough to allow the stressor to be easily delivered to a stream during a rain event along
with unnaturally large amounts of water. DWQ identifies the source of a stressor as specifically
as possible depending on the amount of information available in a watershed. Most often the
source is based on the predominant land use in a watershed. Stressor sources identified in the
Cape Fear River basin during this assessment period include urban or impervious surface areas,
construction sites, road building, land clearing, agriculture and forestry.

27.1.2 Altered Hydrology as the Ultimate Stressor Source

Aquatic communities (benthic macroinvertebrates and fish) in natural or undisturbed watersheds
are impacted only by the most extreme events such as hurricanes or extreme droughts. Even
after these events streams in these watersheds are able to recover. As a watershed is altered,
more stressors (such as chemicals and bacteria) are found in the watershed and because of the
nature of watershed alteration, there are more ways for water to get to streams very rapidly
Chapter 27 – Water Quality Stressors 249

carrying these new stressors. Once a watershed is severely altered, such as in most urban areas,
there are multitudes of stressors in the watershed and many ways for the stressors to affect
aquatic life. Also in these watersheds the important habitats are depleted because the natural
ground cover is removed and trees are rare. The very high flows in heavily altered watersheds
can cause a multitude of instream habitat problems as well. The following stressor discussions
are aimed at identification of specific stressors to the various land uses, but the ultimate cause
and source of these stressors is the altered watershed hydrology.

27.1.3 Overview of Stressors Identified in the Cape Fear River Basin

The stressors noted below are summarized from all waters and for all use support categories.
Figures 30 to 32 identify stressors noted for Impaired waters in the Cape Fear River basin during
the most recent assessment period. The stressors noted in these figures may not be the sole
reason for an Impaired use support rating. Stressors that are listed because of standards
violations may require TMDL development for waters where these stressors are identified. Refer
to subbasin chapters for a complete listing of stressors by waterbody. For specific discussions of
stressors to Impaired waters refer to the subbasin chapters 1 through 24. There are also 4.7 miles
of Atlantic Coastline miles Impaired for recreation where the identified stressor is enterrococcus
(not graphed). All waters in the basin are Impaired in the fish consumption category where
mercury is the stressor of concern. Stressor definitions and impacts are discussed in the
remainder of this chapter.

Noted Stressors to Impaired Reservoirs
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Figure 30 Noted Stressors to Impaired Reservoirs in the Cape Fear River Basin.

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Figure 31 Noted Stressors to Impaired Streams in the Cape Fear River Basin.

Noted Stressors to Impaired Streams
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Figure 32 Noted Stressors to Impaired Estuarine Waters in the Cape Fear River Basin.

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Figures 33 to 35 identify stressors noted for Impacted waters in the Cape Fear River basin during
the most recent assessment period. The stressors noted in these figures did not result in an
Impaired use support rating. Refer to subbasin chapters for a complete listing of stressors by
waterbody. For specific discussions of stressors to Impacted waters refer to the subbasin
chapters 1 through 24. Stressor definitions and impacts are discussed in the remainder of this
chapter.

Figure 33 Noted Stressors to Impacted Reservoirs in the Cape Fear River Basin.

Noted Stressors to Impacted Reservoirs
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Figure 34 Noted Stressors to Impacted Streams in the Cape Fear River Basin.

Noted Stressors to Impacted Streams
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Figure 35 Noted Stressors to Impacted Estuarine Waters in the Cape Fear River Basin.

Noted Stressors to Impacted Estuarine Waters
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27.1.4 Overview of Stressor Sources Identified in the Cape Fear River Basin

The sources noted below are summarized from all waters and for all use support categories.
Figures 36 to 38 identify sources of stressors noted for waters in the Cape Fear River basin
during the most recent assessment period. Refer to subbasin chapters for a complete listing of
sources by waterbody. For specific discussions of stressor sources refer to the subbasin chapters
1 through 24. There are also 10.3 miles of Atlantic Coastline where the identified sources of
stressors are stormwater outfalls to the beach (not graphed).

WWTP NPDES (wastewater treatment plants) were noted as a potential source to many of the
freshwater acres in the Cape Fear River basin. WWTPs contribute nutrients (with other sources)
that may increase the potential for algal blooms and cause exceedances of the chlorophyll a
standard. This can include all discharges upstream of the area of Impairment or noted impacts.
WWTPs were noted as a potential source of water quality problems in 105.8 stream miles. Most
of these impacts were localized and based on permit violations. Better treatment technology and
permit compliance has greatly decreased the number of stream miles locally impacted by
WWTPs.

MS4 NPDES (municipal separate storm sewer systems) were noted as sources to many of the
freshwater acres for the same reasons as the WWTPs discussed above. MS4 was noted as a
potential source when the stream segment was associated with a NPDES permitted municipality.
Unlike the WWTPs, MS4s were noted as a potential source of stressors to 375.8 stream miles
because of the local impacts of runoff from these urban areas. Impervious surface was noted as a
source when field observations indicated that roads and other development not associated with
permitted urban areas was the source of stressors to the stream segment. Impervious surface was
noted as a source of stressors in 77.2 stream miles. Developed land is the most common source
of stressors to water quality in the Cape Fear River basin.
Chapter 27 – Water Quality Stressors 253

Agriculture was noted as a potential source of water quality stressors when field observations
and watershed studies noted agriculture as the predominant land cover. Agriculture was noted as
a source of stressors in 91.8 stream miles. Pasture was also noted as a source when field
observations indicated that cattle had access to streams or streams ran through pasture areas.
Pasture was noted as a potential source of water quality stressors in 36.3 stream miles.
Agriculture and pasture impacts and programs are discussed in more detail in Chapter 28.

Land clearing and road construction were noted as potential sources of water quality stressors to
less than 70 stream miles. Much of the land clearing and road construction is associated with
increased development. Streams where land clearing is a noted source are likely to be more
heavily impacted in the future by increased development.

Figure 36 Sources of Stressors to Reservoirs in the Cape Fear River Basin.

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Figure 37 Sources of Stressors to Streams in the Cape Fear River Basin.

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Figure 38 Sources of Stressors to Estuarine Waters in the Cape Fear River Basin.

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27.2 Aquatic Life Stressors-Habitat Degradation

27.2.1 Introduction and Overview

Instream habitat degradation is identified as a
notable reduction in habitat diversity or a negative
change in habitat. This term may include
sedimentation, lack of organic (woody and leaf)
habitats and channelization. These stressors to
aquatic insect and fish communities can be caused
by many different land use activities and less often
by discharges of treated wastewater into small
streams. In the Cape Fear River basin, over 149.2
stream miles are Impaired where at least one form
of habitat degradation is the stressor. There are an
additional 236.0 stream miles where habitat
degradation is impacting water quality. Many of the
stressors discussed below are either directly caused
by or are a symptom of altered watershed
hydrology. The altered hydrology increases both
sources of stressors and delivery of stressors to
receiving waters. Refer to the subbasin chapters for
more information on the types of habitat
degradation noted at sample locations and in watershed studies.
Some Best Management Practices

Agriculture
Construction
Forestry
• No till or conservation tillage practices
• Strip cropping and contour farming
• Leaving natural buffer areas around
small streams and rivers

• Using phased grading/seeding plans
• Limiting time of exposure
• Planting temporary ground cover
• Using sediment basins and traps

• Controlling runoff from logging roads
• Replanting vegetation on disturbed areas
• Leaving natural buffer areas around
small streams and rivers

Good instream habitat is necessary for aquatic life to survive and reproduce. Streams that
typically show signs of habitat degradation are in watersheds that have a large amount of land-
disturbing activities (construction, mining, timber harvest and agricultural activities) or a large
percentage of impervious surface area. A watershed in which most of the riparian vegetation has
been removed from streams or channelization has occurred also exhibits instream habitat
degradation. Streams that receive a discharge quantity that is much greater than the natural flow
in the stream often have degraded habitat as well. All of these activities result in altered
watershed hydrology.

Quantifying amounts of habitat degradation is very difficult in most cases. To assess instream
habitat degradation in most streams would require extensive technical and monetary resources
and even more resources to restore the stream. Although DWQ and other agencies are starting to
address this issue, local efforts are needed to prevent further instream habitat degradation and to
restore streams that have been Impaired by activities that cause habitat degradation. As point
sources become less of a source of water quality impairment, nonpoint sources that pollute water
and cause habitat degradation need to be addressed to further improve water quality in North
Carolina’s streams and rivers.

27.2.2 Sedimentation

Sedimentation is a natural process that is important to the maintenance of diverse aquatic
habitats. Overloading of sediment in the form of sand, silt and clay particles fills pools and
Chapter 27 – Water Quality Stressors 256

covers or embeds riffles that are vital aquatic insect and fish habitats. A diversity of these
habitats is important for maintenance of biological integrity. Suspended sediment can decrease
primary productivity (photosynthesis) by shading sunlight from aquatic plants, affecting the
overall productivity of a stream system. Suspended sediment also has several effects on various
fish species including avoidance and redistribution, reduced feeding efficiency, and therefore,
reduced growth by some species, respiratory problems, reduced tolerance to diseases and
toxicants, and increased physiological stress (Roell, 1999). Sediment filling rivers, streams and
reservoirs also decreases their storage volume and increases the frequency of floods (NCDENR-
DLR, 1998). Suspended sediment also increases the cost of treating municipal drinking water.
Sediment overloading to many streams has reduced biological diversity to the point of the stream
being Impaired for aquatic life.

Sediment comes from land-disturbing activities in a watershed. The cause of this form of
sedimentation is erosion of land in the watershed. Land-disturbing activities such as the
construction of roads and buildings, crop production, livestock grazing and timber harvesting can
accelerate erosion rates by causing more soil than usual to be detached and moved by water.

Streambank erosion, caused by very high stormwater flows after rain events, is another source of
sediment overloading. Watersheds with large amounts of impervious surfaces transport water to
streams very rapidly and at higher volumes than occurs in watersheds with little impervious
surfaces. In many urban areas, stormwater is delivered directly by storm sewers. This high
volume and velocity of water after rain events undercuts streambanks causing bank failure and
large amounts of sediment to be deposited directly into the stream. Many urban streams are
adversely impacted by sediment overloading from the watershed as well as from the
streambanks.

Sedimentation can be controlled during most land-disturbing activities by using appropriate
BMPs. Substantial amounts of erosion can be prevented by planning to minimize the amount
and time that land is exposed during land-disturbing activities and by minimizing impervious
surface area and direct stormwater outlets to streams. Refer to Chapter 31 for more information
on programs designed to reduce sedimentation.

27.2.3 Lack of Organic Aquatic Habitats

During 2002 basinwide sampling, DWQ biologists reported degradation of aquatic communities
at numerous sites throughout the Cape Fear River basin in association with narrow or nonexistent
zones of native riparian vegetation. Riparian vegetation loss was common in rural and
residential areas as well as in urban areas. The loss of riparian vegetation and subsequent
reduction of organic aquatic habitats is caused by loss of riparian areas, most commonly by land
clearing for development, field agriculture, pastureland, forestry and by grazing animals.
Instream organic habitat removal has also been caused by de-snagging activities.

Removing trees, shrubs and other vegetation to plant grass or place rock (also known as riprap)
along the bank of a river or stream degrades water quality. Removing riparian vegetation
eliminates habitat for aquatic macroinvertebrates that are food for trout and other fish. Rocks or
concrete lining on a bank absorb the sun’s heat and warm the water. Some fish require cooler
water temperatures as well as the higher dissolved oxygen levels cooler water provides. Trees,
shrubs and other native vegetation cool the water by shading it. Straightening a stream, clearing
Chapter 27 – Water Quality Stressors 257

streambank vegetation, and lining the banks with grass or rock severely impact the habitat that
aquatic insects and fish need to survive.

Establishing, conserving and managing streamside vegetation (riparian buffer) is one of the most
economical and efficient BMPs. Forested buffers in particular provide a variety of benefits
including filtering runoff and taking up nutrients, moderating water temperature, preventing
erosion and loss of land, providing flood control and helping to moderate streamflow, and
providing food and habitat for both aquatic and terrestrial wildlife. To obtain a free copy of
DWQ’s Buffers for Clean Water brochure, call [phone], ext. 558.

Organic microhabitat (leafpacks, sticks and large wood) and edge habitat (root banks and
undercut banks) play very important roles in a stream ecosystem. Organic matter in the form of
leaves, sticks and other materials serve as the base of the food web for small streams.
Additionally, these microhabitats serve as special niches for different species of benthic
macroinvertebrates, providing food and/or habitat. For example, many stoneflies are found
almost exclusively in leafpacks and on small sticks. Some beetle species prefer edge habitat,
such as undercut banks. If these microhabitat types are not present, there is no place for these
specialized macroinvertebrates to live and feed. The absence of these microhabitats in some
streams in the Cape Fear River basin is directly related to the absence of riparian vegetation.
Organic microhabitats are critical to headwater streams, the health of which is linked to the
health of the entire downstream watershed.

27.2.4 Channelization

Channelization refers to the physical alteration of naturally occurring stream and riverbeds.
Channelization is caused by mechanical straightening of channels or by hydraulic overloading
during rain events. Often streams in urban areas become channelized as part of the development
process in essence using the stream channels as stormwater conveyances. Although increased
flooding, bank erosion and channel instability often occur in downstream areas after
channelization has occurred, flood control, reduced erosion, increased usable land area, greater
navigability and more efficient drainage are frequently cited as the objectives of channelization
projects (McGarvey, 1996).

Channelization reduces the sinuosity of streams greatly increasing the velocity of water running
these streams. Direct or immediate biological effects of channelization include injury and
mortality of benthic macroinvertebrates, fish, shellfish/mussels and other wildlife populations, as
well as habitat loss. Indirect biological effects include changes in benthic macroinvertebrate,
fish and wildlife community structures, favoring species that are more tolerant of or better
adapted to the altered habitat (McGarvey, 1996).

Restoration or recovery of channelized streams may occur through processes, both naturally and
artificially induced. In general, streams that have not been excessively stressed by the
channelization process can be expected to return to their original forms. However, streams that
have been extensively altered may establish a new, artificial equilibrium (especially when the
channelized streambed has been hardened). In such cases, the stream may enter a vicious cycle
of erosion and continuous entrenchment. Once the benefits of a channelization project become
outweighed by the costs, both in money and environmental integrity, channel restoration efforts
are likely to be taken (McGarvey, 1996).
Chapter 27 – Water Quality Stressors 258

Channelization of streams is extensive and promises to become even more so as urban
development continues. Overall estimates of lost or altered riparian habitats within US streams
are as high as 70 percent. Unfortunately, the dynamic nature of stream ecosystems makes it
difficult (if not impossible) to quantitatively predict the effects of channelization (McGarvey,
1996). Channelization has occurred historically in parts of the Cape Fear River basin and
continues to occur in some watersheds, especially in small headwater streams.

27.3 Aquatic Life Stressors - Water Quality Standards Violations

27.3.1 Introduction and Overview

In addition to the habitat stressors discussed in the previous section, the stressors discussed
below are identified by water quality standards violations. These are usually direct measures of
water quality parameters from ambient water quality monitoring stations. The water quality
standards are designed to protect aquatic life. As discussed above, altered watershed hydrology
greatly increases the sources of these stressors as well as delivery of the stressors to the receiving
waters. The following stressors were identified for waters where greater than 10 percent of the
observations were above the water quality standard. Refer to the subbasin chapters for more
information on the affected waters and the data used to make these assessments.

27.3.2 Arsenic

27.3.3 Chlorophyll a Algal Blooms
Arsenic is a metal that is toxic to aquatic life. Waters are Impaired for aquatic life when greater
than 10 percent of samples collected exceed the state arsenic standard and at least 10 samples
were collected. The arsenic water quality standard for Class C waters is 50 µg/l. In the Cape
Fear River basin during this assessment period, there were 6.6 stream miles where arsenic was
the identified stressor (see Chapter 8).

Algae are aquatic, microscopic plants, which respond to nutrients, temperature and light, and are
an important food source for fish and other aquatic animals. Algae also contain pigments,
including chlorophyll, which enable them to photosynthesize and produce oxygen. During
summer, algae respond to warm temperatures, high light and nutrients washed into waterways
after rain events and from treated wastewater. When temperatures and nutrient concentrations
are elevated, algae reproduce to high concentrations ("bloom"). When this occurs at a particular
site, chlorophyll a, dissolved oxygen (DO) and pH increase. When a site experiences dissolved
oxygen concentrations >9 mg/l, DO percent saturation >110%, pH >8, or chlorophyll a
concentrations exceed the state standard of 40 µg/l, the site is likely experiencing an algal bloom.
When these algae die off or respire at night, dissolved oxygen can become very low. Many
times low dissolved oxygen caused by algal die off can cause fish kills. Algal blooms have been
a problem in lakes, reservoirs and estuaries that are overloaded with nutrients.

Waters are Impaired for aquatic life when greater than 10 percent of samples collected exceed
the state chlorophyll a standard of 40 µg/l and at least 10 samples were collected. In the Cape
Fear River basin during this assessment period, there were 10,833.9 freshwater acres and 11.7
Chapter 27 – Water Quality Stressors 259

stream miles that are Impaired where chlorophyll a is a stressor. There were also 2,239.8
freshwater acres and 32.6 stream miles that are impacted where chlorophyll a is a stressor.

27.3.4 Low Dissolved Oxygen

Maintaining an adequate amount of dissolved oxygen (DO) is critical to the survival of aquatic
life and to the general health of surface waters. A number of factors influence DO
concentrations including water temperature, depth and turbulence. Additionally, in the Cape
Fear River basin, a large floodplain drainage system and flow management from upstream
impoundments also influences DO. Oxygen-consuming wastes such as decomposing organic
matter and some chemicals can reduce DO levels in surface water through biological activity and
chemical reactions. NPDES permits for wastewater discharges set limits on certain parameters
in order to control the effects that oxygen depletion can have in receiving waters.

Waters are Impaired for aquatic life when greater than 10 percent of samples collected exceed
the state DO standard and at least 10 samples were collected. The DO water quality standard for
Class C waters is not less than a daily average of 5 mg/l with a minimum instantaneous value of
not less than 4 mg/l. For Class SC waters the standard is 5 mg/l. Swamp waters (supplemental
Class Sw) may have lower values if caused by natural conditions. In the Cape Fear River basin
during this assessment period, there were 6,527.4 estuarine acres and 43.9 stream miles that are
Impaired where low DO is a stressor. There were also over 667.5 freshwater acres, 264.9 stream
miles and 1.0 estuarine acres where low DO is a stressor, although many of these streams are in
swampy areas where low DO levels are likely from natural sources.

27.3.5 pH

Waters are Impaired for aquatic life when greater than 10 percent of samples collected exceed
the state pH standard and at least 10 samples were collected. The pH water quality standard for
Class C waters is between 6.0 and 9.0. For Class SC waters the standard is between 6.8 and 8.5.
Swamp waters (supplemental Class Sw) may have lower values if caused by natural conditions.
In the Cape Fear River basin during this assessment period, there were 97.9 stream miles and
6,360.4 estuarine acres that are Impaired where low pH is a stressor. There were 1,445.5
freshwater acres that are Impaired where high pH is a stressor. There were also 3,799.6
freshwater acres and 107.2 stream miles that are impacted where low pH is a stressor, although
many of these streams are in swampy areas where low pH levels are likely from natural sources.

27.3.6 Total Suspended Solids

Total suspended solids (TSS) are noted as a stressor when identified from NPDES compliance
reports. Waters are not Impaired due to TSS permit violations. In the Cape Fear River basin
during this assessment period, there were 12.4 stream miles impacted where TSS is a stressor.

27.3.7 Toxic Impacts
Toxic impacts are noted as a stressor when identified during biological community monitoring.
Waters are not Impaired due to toxic impacts. In the Cape Fear River basin during this
assessment period, there were 10.8 stream miles Impaired where toxic impacts are a stressor.
Chapter 27 – Water Quality Stressors 260

27.3.8 Turbidity

Waters are Impaired for aquatic life when greater than 10 percent of samples collected exceed
the state turbidity standard and at least 10 samples were collected. The turbidity water quality
standard for Class C waters is not to exceed 50 Nephelometric Turbidity Units (NTU). In the
Cape Fear River basin during this assessment period, there were 115.4 stream miles and 5,616.7
estuarine acres that are Impaired where turbidity is a stressor. There were also 685.5 freshwater
acres and 127.7 stream miles that are impacted where turbidity is a stressor.

27.4 Recreation Stressors - Pathogens

27.4.1 Fecal Coliform Bacteria

Water quality standards for fecal coliform bacteria are intended to ensure safe use of waters for
recreation (refer to Administrative Code Section 15A NCAC 2B .0200). The North Carolina
fecal coliform standard for freshwater is 200 colonies/100ml based on the geometric mean of at
least five consecutive samples taken during a 30-day period and not to exceed 400
colonies/100ml in more than 20 percent of the samples during the same period. In the Cape Fear
River basin, there are 40.9 stream miles where this standard was exceeded. These waters are
Impaired for recreation. In 154.6 stream miles fecal coliform bacteria is a noted stressor because
annual screening criteria were exceeded. These waters were not intensively sampled to assess
the standard as described above, but had either a geometric above 200 colonies/100ml and/or 20
percent of samples exceeded 400 colonies/100ml over the five-year assessment period. These
waters are discussed in the subbasin chapters. A total of 19,339 acres, 1,119.9 stream miles and
48.6 coastline miles were monitored for recreation.

A number of factors beyond the control of any state regulatory agency contribute to elevated
levels of disease-causing bacteria. Therefore, the state does not encourage swimming in surface
waters. To assure that waters are safe for swimming indicates a need to test waters for
pathogenic bacteria. Although fecal coliform standards have been used to indicate the
microbiological quality of surface waters for swimming for more than 50 years, the value of this
indicator is often questioned. Evidence collected during the past several decades suggests that
the coliform group may not adequately indicate the presence of pathogenic viruses or parasites in
water.

Fecal coliform bacteria live in the digestive tract of warm-blooded animals (humans as well as
other mammals) and are excreted in their waste. Fecal coliform bacteria do not actually pose a
danger to people or animals. However, where fecal coliform are present, disease-causing
bacteria may also be present and water that is polluted by human or animal waste can harbor
other pathogens that may threaten human health.

The presence of disease-causing bacteria tends to affect humans more than aquatic creatures.
High levels of fecal coliform bacteria can indicate high levels of sewage or animal wastes that
could make water unsafe for human contact (swimming). Fecal coliform bacteria and other
potential pathogens associated with waste from warm-blooded animals are not harmful to fish
and aquatic insects. However, high levels of fecal coliform bacteria may indicate contamination
that increases the risk of contact with harmful pathogens in surface waters. Pathogens associated
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with fecal coliform bacteria can cause diarrhea, dysentery, cholera and typhoid fever in humans.
Some pathogens can also cause infection in open wounds.

Under favorable conditions, fecal coliform bacteria can survive in bottom sediments for an
extended period (Howell et al., 1996; Sherer et al., 1992; Schillinger and Gannon, 1985).
Therefore, concentrations of bacteria measured in the water column can reflect both recent inputs
as well as the resuspension of older inputs.

Reducing fecal coliform bacteria in wastewater requires
a disinfection process, which typically involves the use
of chlorine and other disinfectants. Although these
materials may kill the fecal coliform bacteria and other
pathogenic disease-causing bacteria, they also kill
bacteria essential to the proper balance of the aquatic
environment, and thereby, endanger the survival of
species dependent on those bacteria.
Sources of Fecal Coliform
in Surface Waters

• Urban stormwater
• Wild animals and domestic pets
• Improperly designed or managed
animal waste facilities
The detection and identification of specific pathogenic
bacteria, viruses and parasites such as Giardia,
Cryptosporidium and Shigella are expensive, and
results are generally difficult to reproduce
quantitatively. Also, to ensure the water is safe for
swimming would require a whole suite of tests for
many organisms, as the presence/absence of one
organism would not document the presence/absence of another. This type of testing program is
not possible due to resource constraints.
• Livestock with direct access to
streams
• Improperly treated discharges of
domestic wastewater, including
leaking or failing septic systems
and straight pipes
27.4.2 Enterrococcus-Recreational Beach Monitoring

Enterrococcus is the pathogen indicator used by DEH Recreational Water Quality Monitoring
Program to assess recreation in coastal waters. DWQ does not directly use enterococcus data to
assign use support ratings. Waters are Impaired when swimming advisories are posted for more
than 61 days during the five year assessment period. In the Cape Fear River basin 96.6 estuarine
acres and 4.7 Atlantic coastline miles are Impaired for recreation because of swimming
advisories posted during the assessment period. Enterrococcus is the stressor in these waters.
27.5 Fish Consumption Stressors - Mercury

The presence and accumulation of mercury in North Carolina’s aquatic environment are similar
to contamination observed throughout the country. Mercury has a complex life in the
environment, moving from the atmosphere to soil, to surface water and into biological
organisms. Mercury circulates in the environment as a result of natural and human
(anthropogenic) activities. A dominant pathway of mercury in the environment is through the
atmosphere. Mercury that has been emitted from industrial and municipal stacks into the
ambient air can circulate across the globe. At any point, mercury may then be deposited onto
land and water. Once in the water, mercury can accumulate in fish tissue and humans. Mercury
is also commonly found in wastewater.
Chapter 27 – Water Quality Stressors 262

The NC Department of Health and Human Services issues fish consumption advisories and
advice for those fish species which have median and/or average methyl mercury levels at 0.4
mg/kg or greater. These fish include shark, swordfish, king mackerel, tilefish, as well as
largemouth bass, bowfin (or blackfish) and chain pickerel (or jack) in North Carolina waters
south and east of Interstate 85. See Fish Consumption Advice below. Refer to Appendix X for
more information regarding use support ratings and assessment methodology. DWQ has
sampled fish tissue from 13 locations in the Cape Fear River basin. Refer to subbasin chapters
for more information on these waters.
For more detailed information, visit EPA’s internet site at http://www.epa.gov/waterscience/fish/ or
visit http://www.cfsan.fda.gov/seafood1.html or call the FDA’s food information line toll-free at 1-888-
SAFEFOOD.

For more information and detailed listing of site-specific advisories, visit the NC Department of
Health and Human Services website at http://www.schs.state.nc.us/epi/fish/current.html or call (919)
733-3816.

27.6 Shellfish Harvesting Stressors - Fecal Coliform Bacteria

DWQ does not directly use DEH Shellfish Sanitation Section (DEH SS) fecal coliform bacteria
data to make use support determinations in Class SA waters. DWQ relies on the growing area
status of waters in the Cape Fear River basin that are monitored by DEH SS. Class SA waters
that are in a DEH SS Approved classification are Supporting in the shellfish harvesting use
support category by DWQ. All other DEH SS growing area classifications are considered to be
Impaired in the shellfish harvesting category by DWQ. In the Cape Fear River basin, there are
2,654.2 acres of prohibited waters, 94.2 acres of conditionally approved-closed waters, and
3,822.8 acres of conditionally approved-open waters. All of these waters (6,571.2 acres) are
Impaired for shellfish harvesting and the stressor is fecal coliform bacteria.

Chapter 27 – Water Quality Stressors 263