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Watauga River Basin Plan Chapter 3

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Watauga River Basin Plan Chapter 3 ...

    WATAUGA RIVER BASIN PLAN CHAPTER 3

    CAUSES AND SOURCES OF WATER POLLUTION

     IN THE WATAUGA RIVER BASIN

3.1 INTRODUCTION

Water pollution is caused by a number of substances including sediment, nutrients, bacteria, oxygen-

    demanding wastes, metals, color and toxic substances. Sources of these pollution-causing

    substances are divided into broad categories called point sources and nonpoint sources. Point

    sources are typically piped discharges from wastewater treatment plants and large urban and

    industrial stormwater systems. Nonpoint sources can include stormwater runoff from small urban

    areas (population less than 100,000), forestry, mining, agricultural lands, rural residential

    development, and others. Section 3.2 identifies and describes the major causes of pollution in the basin. Sections 3.3 and 3.4 describe point and nonpoint source pollution in the basin.

    3.2 DEFINING CAUSES OF POLLUTION

The term causes of pollution refers to the substances which enter surface waters from point and

    nonpoint sources and result in water quality degradation. The major causes of pollution discussed

    throughout the basin plan include biochemical oxygen demand (BOD), sediment, nutrients,

    toxicants (such as heavy metals, chlorine, pH and ammonia) and fecal coliform bacteria. Each of

    the following descriptions indicates whether the cause is point or nonpoint source-related (or both).

3.2.1 Sedimentation

Sediment is the most widespread cause of stream degradation and potential impairment in the

    Watauga River basin. While no streams in the Watauga River basin are classified as impaired due

    to sedimentation, Laurel Fork has been rated Support-Threatened due to sediments. Several other

    streams have been determined to be impacted to a lesser degree by sedimentation.

Sedimentation is the most widespread cause of nonpoint source pollution in the state and results

    from land-disturbing activities including agriculture, construction, urban runoff, streambank erosion,

    mining and forestry. Sedimentation is often divided into two categories: suspended load and bed

    load . Suspended load is composed of small particles that remain in the suspension in the water.

    Bed load is composed of larger particles that slide or roll along the stream bottom. Suspension of

    load types depends on water velocity and stream characteristics. Biologists are primarily concerned

    with the concentration of the suspended sediments and the degree of sedimentation on the

    streambed (Waters 1995).

The concentration of suspended sediments affects the availability of light for photosynthesis, as well

    as the ability of aquatic animals to see their prey. Several researchers have reported reduced feeding

    and growth rates by fish in waters with high suspended solids. In some cases it was noted that young

    fish left those stream segments with turbid conditions. Suspended sediments can clog the gills of fish

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    Chapter 3 - Causes and Sources of Water Pollution

    and reduce their respiratory abilities. These forms of stress may reduce the tolerance level of fish to disease, toxicants and chronic turbid conditions. Suspended solids are reported as Total Suspended Solids or as Turbidity. They are measured in parts per million, milligrams per liter (Waters 1995) or NTUs.

    The degree of sedimentation affects both the habitat of aquatic macroinvertebrates and the quality and amount of fish spawning and rearing habitat. Degree of sedimentation can be estimated by observing the amount of streambed covered, the depth of sedimentation, and the percent saturation of interstitial space or embeddedness. Eggs and fry in interstitial spaces may be suffocated by the sediments thereby reducing reproductive success (Waters 1995). Effects of sedimentation on macroinvertebrates can be seen in alterations in community density, diversity, and structure (Lenat et al. 1979).

    The impact of sedimentation on fish populations depends on both concentration and degree of sedimentation, but impact severity can also be affected by the duration (or dose) of sedimentation. Suspended sediments may occur at high concentrations for short periods of time, or at low concentrations for extended periods of time. The greatest impacts to fish populations will be seen at high concentrations for extended time periods. The use of a dose-response matrix in combination with field investigations can help predict the impact of suspended sediments on various life stages of fish populations (Newcombe 1996).

    Sedimentation impacts streams in several other ways. Eroded sediments may gradually fill lakes and navigable waters and may increase drinking water treatment costs. Sediment also serves as a carrier for other pollutants including nutrients (especially phosphorus), toxic metals, pesticides and road salts.

    North Carolina does not have a numeric water quality standard for suspended solids. However, all dischargers must meet federal effluent guideline values at a minimum (e.g. 30 mg/l for domestic discharges). Also, most point source BOD limitations require treatment to remove sediments to a level below federal guideline requirements. Discharges to high quality waters (HQW) must meet a total suspended solids (TSS) limit of 10 mg/l for trout waters and primary nursery areas and 20 mg/l for all other HQWs. In addition, the state has adopted a numerical instream turbidity standard for point and nonpoint source pollution. Nonpoint sources are considered to be in compliance with the standard if approved best management practices (BMPs) have been implemented.

    Statistics compiled by the US Department of Agriculture, Natural Resource Conservation Service (formerly known as the Soil Conservation Service) indicate a statewide decline in erosion from 1982 to 1992 (USDA, NRCS, 1992) as shown in Table 3.1.

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    Table 3.1 Overall Erosion Trends in North Carolina

     1982 1987 1992

    Area (1,000 acres) 33,708.2 33,708.2 33,708.2

    Gross Erosion (1,000 tons/yr) 46,039.5 43,264.6 36,512.9

    Erosion Rate (Tons/Yr/Ac) 1.4 1.3 1.1

    The NRCS statistics also indicate a statewide reduction per acre on cropland erosion using the Universal Soil Loss Equation (Table 3.2).

Table 3.2 USLE Erosion on Cultivated Cropland in North Carolina

     1982 1987 1992

    Cropland Area (1,000 acres) 6,318.7 5956.8 5538.0

    Gross Erosion (1,000 tons/yr) 40,921.4 37475.3 30,908.3

    Erosion Rate (Tons/Yr/Ac) 6.5 6.3 5.6

    However, in the Blue Ridge Mountains region, which encompasses the entire Watauga River basin and several others, the overall erosion picture is less clear. Table 3.3 shows a significant decline in cultivated cropland acreage and a corresponding decline in gross erosion over the past ten years, but the erosion rate per acre increased from 12.7 tons/acre/year in 1982 to 20.8 tons/acre/year in 1987 and then dropped to 18.3 tons/acre/year in 1992. Non-cultivated cropland erosion rates also increased over the ten year period from 1.4 tons/acre/year in 1982 to 1.7 tons/acre/year although pasture land rates dropped from 2.6 to 2.2 tons/acre/year over the same period.

    According to the Raleigh NRCS office, several factors may explain the large erosion rate increase from 1982 to 1987. The mountains were the last region of the state to be accurately soil-mapped, and so more recent data may reflect an improved knowledge of soil loss. Secondly, there have been some revisions in soil loss coefficients for individual soil types. And third, Christmas tree farms have been included in the cropland acreage figures. Many farms are located on extremely steep lands and the large increase in the Christmas tree industry could play an important role in these numbers.

Table 3.3 North Carolina Erosion in Blue Ridge Mountain Region

     1982 1987 1992

    Cropland Area (1,000 acres) 122.9 97.9 76.2

    Gross Erosion (1,000 tons/yr) 1555.6 2035.2 1397.5

    Erosion Rate (Tons/Yr/Ac) 12.7 20.8 18.3

    Compared with other regions of the state, the overall erosion rate per acre for cultivated cropland in the mountains is very high although it is noted that the rate has dropped since 1987 (Table 3.4).

Table 3.4 North Carolina Erosion on Major Land Resource Areas (MLRA)

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     1982 1987 1992

    Blue Ridge Mountains 12.7 20.8 18.3

    Southern Piedmont 12.3 12.0 10.5

    Carolina and Georgia

     Sand Hills 6.0 5.6 5.1

    Southern Coastal Plain 3.9 3.9 4.0

    Atlantic Coast Flatwoods 3.2 3.1 3.2

    Tidewater Area 1.4 1.5 1.6

    Much of this data relates to cropland, including Christmas tree farms, and the need to continue to improve cropland erosion controls in the mountains. It also carries a broader message of the high erosion potential in the mountains, not only from agricultural activities, but for all land-disturbing activities on the steep slopes which are so prevalent in this region. Of particular concern are potential sediment losses from logging operations, Christmas tree farms, streambank erosion, second home development and highway construction.

    Streambank erosion is a natural process, but one that is accelerated by human activities. Streambank erosion results from two processes: high flows and bank failures. Growth is associated with an increase in impervious surfaces, resulting in higher volumes and rates of flow into receiving streams. The Watauga River basin, as noted earlier, has seen a 212% increase in urban growth. Bank failures can occur due to these high flows, or from heavy use of streambanks for cattle or vehicle crossings. Loss of buffer strips along streambanks can also greatly contribute to bank erosion. The use of structural techniques such as: bank sloping, use of tree roots for stabilization, buffer strips, and fencing cattle out of streams can greatly reduce streambank erosion. Average annual soil loss has shown decreases of 40% after cattle were fenced away from streams. This decrease resulted in nearly a 60% reduction in average sediment concentration during stormflow events (Owens, et al 1996).

    Most sediment-related impacts are associated with nonpoint source pollution. Programs aimed at addressing sedimentation are listed in Chapter 6 and are briefly described under nonpoint source pollution controls in Chapter 5. Nonpoint sources are considered to be in compliance with the standard if approved best management practices (BMPs) have been implemented.

3.2.2 Oxygen-Consuming Wastes

    Oxygen-consuming wastes include decomposing organic matter or chemicals that reduce dissolved oxygen in the water column through chemical reactions or biological activity. Maintaining a sufficient level of dissolved oxygen in the water is critical to most forms of aquatic life, especially trout.

    A number of factors affect dissolved oxygen concentrations. Higher dissolved oxygen is produced by turbulent actions, such as waves, rapids and waterfalls, which mix air and water. Lower water

    temperature also generally allows for retention of higher dissolved oxygen concentrations.

    Therefore, the cool swift-flowing streams of the mountains are generally high in dissolved oxygen. Low dissolved oxygen levels tend to occur more often in warm, slow-moving waters that receive a high input of effluent from wastewater treatment plants during low flow conditions. In general, the lowest dissolved oxygen concentrations occur during the warmest summer months and particularly

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    during low flow periods. Water depth is also a factor. In deep slow-moving waters, such as

    reservoirs or estuaries, dissolved oxygen concentrations may be very high near the surface due to

    wind action and plant (algae) photosynthesis but may be entirely depleted (anoxic) at the bottom.

Sources of dissolved oxygen depletion include wastewater treatment plant effluent, the

    decomposition of organic matter (such as leaves, dead plants and animals) and organic waste matter

    that is washed or discharged into the water. Sewage from human and household wastes is high in

    organic waste matter, as is waste from trout farms. Bacterial decomposition can rapidly deplete

    dissolved oxygen levels unless these wastes are adequately treated at a wastewater treatment plant.

    In addition, some chemicals may react with and bind up dissolved oxygen. Industrial discharges

    with oxygen consuming wasteflow may be resilient instream and continue to use oxygen for a long

    distance downstream.

Oxygen-Consuming Wastes in the Watauga River Basin

    Oxygen-consuming wastes have not been identified as a significant source of water quality

    impairment in the Watauga River basin.

3.2.3 Nutrients

The term nutrients in this document refers to the two major plant nutrients, phosphorus and nitrogen.

    These are common components of fertilizers, animal and human wastes, vegetation and some

    industrial processes. Nutrients in surface waters come from both point and nonpoint sources.

    Nutrients are beneficial to aquatic life in small amounts. However, in overabundance and under

    favorable conditions, they can stimulate the occurrence of algal blooms and excessive plant growth

    in quiet waters such as ponds, lakes, reservoirs and estuaries.

Nutrients in the Watauga River Basin

    Nutrients have not been identified as a significant source of water quality impairment in the

    Watauga River basin.

3.2.4 Toxic Substances

Regulation 15A NCAC 2B. 0202(36) defines a toxicant as "any substance or combination of

    substances ... which after discharge and upon exposure, ingestion, inhalation, or assimilation into

    any organism, either directly from the environment or indirectly by ingestion through food chains,

    has the potential to cause death, disease, behavioral abnormalities, cancer, genetic mutations,

    physiological malfunctions (including malfunctions or suppression in reproduction or growth) or

    physical deformities in such organisms or their offspring or other adverse health effects". Toxic

    substances frequently encountered in water quality management include chlorine, ammonia,

    organics (hydrocarbons and pesticides) heavy metals and pH. These materials are toxic to different

    organisms in varying amounts. The effects may be evident immediately, or may only be manifested

    after long-term exposure or accumulation in living tissue.

North Carolina has adopted standards and action levels for several toxic substances. These are

    contained in 15A NCAC 2B .0200. Usually limits are not assigned for parameters which have

    action levels unless 1) monitoring indicates that the parameter may be causing toxicity or, 2) federal

    guidelines exist for a given discharger for an action level substance. This process of determining

    action levels exists because these toxic substances are generally not bioaccumulative and have

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    Chapter 3 - Causes and Sources of Water Pollution

    variable toxicity to aquatic life because of chemical form, solubility, stream characteristics and/or associated waste characteristics. Water quality based limits may also be assigned to a given NPDES permit if data indicate that a substance is present for which there is a federal criterion but no water quality standard.

    Whole effluent toxicity (WET) testing is required on a quarterly basis for major NPDES dischargers and any discharger containing complex (industrial) wastewater. This test shows whether the effluent from a treatment plant is toxic, but it does not identify the specific cause of toxicity. If the effluent is found to be toxic, further testing is done to determine the specific cause. This follow-up testing is called a toxicity reduction evaluation (TRE). WET testing is discussed in Chapter 4 and Appendix III. Other testing, or monitoring, done to detect aquatic toxicity problems include fish tissue analyses, chemical water quality sampling and assessment of fish community and bottom-dwelling organisms such as aquatic insect larvae. These monitoring programs are discussed in Chapter 4.

Toxic substances in the Watauga River Basin

    There are no waters in the Watauga River basin known to be impacted by toxic substances.

3.2.5 Fecal Coliform Bacteria

    Fecal coliform bacteria has not been identified as a problem parameter in the Watauga River basin at the three ambient monitoring stations in the basin. However, the Valle Crucis and Sugar Grove sites on the Watauga River showed elevated fecal coliform concentrations.

    Fecal coliform bacteria are typically associated with the intestinal tract of warm-blooded animals. Common sources of fecal coliform bacteria include leaking or failing septic systems, leaking sewer lines or pump station overflows, runoff from livestock operations and wildlife, and improperly disinfected wastewater effluent.

    Fecal coliform bacteria are widely used as indicators of the potential presence of waterborne pathogenic organisms (which cause such diseases as typhoid fever, dysentery, and cholera). Fecal coliform bacteria in treatment plant effluent are controlled through disinfection methods including chlorination (sometimes followed by dechlorination), ozonation or ultraviolet light radiation.

    Due to the low number of farm animal operations and limited development in the basin, the chances of bacterial contamination in streams is relatively low. However, failing septic systems, straight piping of waters to streams and animal operations without appropriate best management practices in place can cause elevated bacterial levels in any of the many unmonitored streams.

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    Chapter 3 - Causes and Sources of Water Pollution

    3.3 POINT SOURCES OF POLLUTION

    3.3.1 Defining Point Sources

    Point sources refers to discharges that enter surface waters through a pipe, ditch or other well-defined points of discharge. The term most commonly refers to discharges associated with

    wastewater treatment plant facilities. These include municipal (city and county) and industrial

    wastewater treatment plants as well as small domestic discharging treatment systems that may serve

    schools, commercial offices, residential subdivisions and individual homes. In addition, discharges

    from stormwater systems at industrial sites are now considered point source discharges and are being regulated under new urban stormwater runoff regulations being required by the U.S.

    Environmental Protection Agency (EPA). The urban stormwater runoff program is discussed in

    more detail in Chapter 5 and in Chapter 6. The primary substances and compounds associated with

    point source pollution are oxygen-demanding wastes, nutrients, color and toxic substances including

    chlorine, ammonia and metals.

Point source discharges are not allowed in North Carolina without a permit from the state.

    Discharge permits are issued under the National Pollutant Discharge Elimination System (NPDES)

    program delegated to North Carolina from EPA. The amount or loading of specific pollutants that

    may be allowed to be discharged into surface waters are defined in the NPDES permit and are called

    effluent limits. Under the NPDES permitting program, each NPDES discharger is assigned either

    major or minor status. Major facilities are large with greater flows. For municipalities, all dischargers with a flow of greater than 1 million gallons per day (MGD) are classified as major.

    Most point source discharges, other than urban and industrial stormwater discharges, are continuous

    and do not occur only during storm events as do nonpoint sources. They generally have the most

    impact on a stream during low flow conditions when the percentage of stream flow composed of

    treated effluent is greatest. Permit limits are generally set to protect the stream during low flow

    conditions. The standard low flow used for determining point source impacts is called the 7Q10.

    This is the lowest flow which occurs over seven consecutive days and which has an average

    recurrence of once in ten years.

Information is collected on NPDES permitted discharges in several ways. The major method of

    collection is facility self-monitoring data which are submitted monthly to the DWQ by each

    individual permittee. NPDES facilities are required to monitor for all pollutants for which they have

    limits as well as other pollutants which may be present in their wastewater. All domestic wastewater

    dischargers are required to monitor flow, dissolved oxygen, temperature, fecal coliform, BOD,

    ammonia, and chlorine (if they use it as a disinfectant). In addition, facilities with industrial sources

    may have to monitor for chemical specific toxicants and/or whole effluent toxicity (see Section

    3.2.3); and all dischargers with design flows greater than 50,000 gallons per day (GPD) monitor for

    total phosphorus and total nitrogen. Minimum NPDES monitoring requirements are provided in

    15A NCAC 2B .0500.

Other methods of collecting point source information include effluent sampling by DWQ during

    inspections and special studies. The regional offices may collect data at a given facility if they

    believe there may be an operational problem or as a routine compliance check. In addition, the

    DWQ may collect effluent data during intensive surveys of segments of streams, and extensive

    discharger data have been collected during onsite toxicity tests.

    3.3.2 Point Source Discharges in the Watauga River Basin

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In the Watauga River basin, there are 40 permitted NPDES dischargers. All NPDES permit

    renewals occur within a prescribed time period after completion of the basinwide water quality

    management plan. Permit renewals are repeated at five year intervals. Permits for the Watauga

    River basin are scheduled to be renewed in September 1997. A distribution map of the discharge

    facilities is shown in Figure 3.1. A list of all NPDES dischargers in the basin can be found in Table

    3.5. Twenty-nine of these facilities have individual NPDES permits (NC00 facilities), seven are

    stormwater facilities, and four are general permits (NCG facilities). The total permitted flow for all

    facilities is 2.28 million gallons per day (MGD). The average actual flow from all facilities is 3.39

    MGD. Table 3.6 summarizes the number of dischargers and their total permitted and average 1996

    flows for each subbasin. Table 3.7 provides definitions of the NPDES categories.

    There are numerous facilities which have permits with no flow limits. Cooling towers, groundwater remediation sites, and other non-process industrial facilities are the most common examples of this.

    However, due to monitoring requirements, these sites report flow data. Since there are no flow

    limits for these sites in the database, the sites (and the subbasin) appear to be generating more flow

    that the permits allow.

There is one trout farm, Grandfather Trout Ponds, in the Watauga River basin near Foscoe in

    Watauga county. The farm is under an NCG facility permit. Trout farms can be a source of

    nutrients to surface waters if the farms are not managed properly. The impacts from trout farms are

    typically found within a short stream length from the farm. In this way, impacts from trout

    production are localized and can result in lower macroinvertebrate ratings. Changes caused by trout

    farms can be in the form of algal production and higher than normal nutrients. The effects from

    trout farms are more often seen during low flows and high water temperatures. Trout farms can also

    cause water quality problems if there is more than one farm on a stream reach. See Appendix IV for

    the requirements of a general permit.

Figure 3.1 Map of NPDES Dischargers in the Watauga River Basin

    Table 3.5 NPDES Dischargers in the Watauga River Basin

Table 3.5 NPDES Dischargers in the Watauga River Basin (continued)

Table 3.5 NPDES Dischargers in the Watauga River Basin (continued)

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    Chapter 3 - Causes and Sources of Water Pollution

    Table 3.6 Summary of Major/Minor NPDES Dischargers and Permitted and Actual Flows or

    the Watauga River Basin.

     SUBBASIN FACILITY CATEGORIES 01 TOTALS Total Facilities 40 40 NC00 Facilities* 29 29 Stormwater Facilities 7 7 NCG General Permit Facilities 4 4 Total Permitted Flow (MGD) 2.28 2.28 # of Facilities Reporting 25 25 Total Avg. Flow (MGD) 3.39 3.39 *Major Discharges 0 0 Total Permitted Flow (MGD) 0 0 # of Facilities Reporting 0 0 Total Avg. Flow (MGD) 0.00 0.00 *Minor Discharges 29 29 Total Permitted Flow (MGD) 2.28 2.28 # of Facilities Reporting 25 25 Total Avg. Flow (MGD) 3.39 3.39 100% Domestic Wastewater 19 19 Total Permitted Flow (MGD) 1.11 1.11 # of Facilities Reporting 19 19 Total Avg. Flow (MGD) 2.89 2.89 Municipal Facilities 4 4 Total Permitted Flow (MGD) 1.14 1.14 # of Facilities Reporting 3 3 Total Avg. Flow (MGD) 0.48 0.48 Major Process Industrial 0 0 Total Permitted Flow (MGD) 0 0 # of Facilities Reporting 0 0 Total Avg. Flow (MGD) 0.00 0.00 Minor Process Industrial 3 3 Total Permitted Flow (MGD) 0.02 0.02 # of Facilities Reporting 3 3 Total Avg. Flow (MGD) 0.01 0.01 Nonprocess Industrial 0 0 Total Permitted Flow (MGD) 0.00 0.00 # of Facilities Reporting 0 0 Total Avg. Flow (MGD) 0.00 0.00 * NC00 / Individual permit facilities

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Chapter 3 - Causes and Sources of Water Pollution

    Table 3.7 Definitions of Categories of NPDES Permits

    CATEGORY DEFINITION EXAMPLES

    For publicly owned treatment works, any There are no major dischargers in the Major vs. Minor

    facility discharging over 1 MGD is defined Watauga River basin. discharges as a Major discharge.

    For industrial facilities, the EPA provides

    evaluation criteria including daily discharge,

    toxic pollutant potential, public health

    impact and water quality factors.

    Any facilities which do not meet the criteria

    for Major status are defined as Minor

    discharges.

    A system which treats wastewater containing Housing subdivision WWTPs, schools, 100% Domestic

    household-type wastes (bathrooms, sinks, mobile home parks.

    washers, etc.).

    A system which serves a municipality of any NC0069761- Beech Mountain/Pond Municipal

    size. Creek WWTP

    Water used in an industrial process which NCG530047 - Grandfather Trout Ponds Process Industrial

    must be treated prior to discharge. (trout farm and gem mining)

    Wastewater which requires no treatment There are no facilities of this type in the Nonprocess

    1basin. Industrial prior to discharging.

    Discharges of runoff from rainfall or snow "Stormwater discharges associated with Stormwater

    melt. industrial activity" include most types of 2Facilities manufacturing plants. Light manufac-

    NPDES permits are required for "stormwater turing is subject only if they process or

    discharges associated with industrial store materials outdoors.

    activity" and from municipal stormwater Landfills, mines, junkyards, steam

    systems for towns over 100,000 in electric plants, transportation terminals

    population. and any construction activity which

    disturbs 5 acres or more during

    construction.

1. Non-contact cooling water may contain biocides; however, the biocides must be approved by our Aquatic Survey

    and Toxicology Unit. The approval process verifies that the chemicals involved have no detrimental effect on the

    stream when discharged with the non-contact cooling water.

2. Stormwater facilities are covered by General Permits NCG010000 through NCG190000. Facilities which do not

    fit the categories of these permits are covered under individual stormwater permits NCS000000.

3.4 NONPOINT SOURCES OF POLLUTION

Nonpoint source (NPS) pollution refers to runoff that enters surface waters through stormwater,

    snowmelt or atmospheric deposition (e.g. acid rain). There are many types of land use activities that

    are a source of nonpoint source pollution including land development, construction, crop production,

    animal feeding lots, failing septic systems, landfills, roads and parking lots. As noted earlier,

    stormwater from large urban areas (>100,000 people) and from certain industrial sites is considered

    a point source since NPDES permits are required for piped discharges of stormwater from these

    areas. However, a discussion of urban runoff will be included in this section.

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