Water quality in the upper Tennessee River basin, Tennessee, North Carolina, Virginia, and Georgia 1994-98

POINTS OF CONTACT AND ADDITIONAL INFORMATION

The companion Web site for NAWQA summary reports:

http://water.usgs.gov/nawqa/

Upper Tennessee River Basin contact and Web site:

District Chief

Water Resources Division 640 Grassmere Park Drive, Suite 100 Nashville, TN 37211 e-mail: dc_tn@usgs.gov http://tn.water.usgs.gov/

Other NAWQA summary reports

Front cover: Clear Creek, Tennessee (courtesy of National Park Service, Obed Wild and Scenic River). Back cover: Tobacco in Cocke County, Tennessee (photograph by G.C. Johnson, U.S. Geological Survey); center, Whitewater rafting (photograph courtesy of National Park Service, Obed Wild and Scenic River); right, French Broad River Valley, North Carolina (photograph by P.S. Hampson, U.S. Geological Survey). National NAWQA Program:

Chief, NAWQA Program

Water Resources Division 12201 Sunrise Valley Drive, M.S. 413 Reston, VA 20192 http://water.usgs.gov/nawqa/

By Paul S. Hampson, M.W. Treece, Jr., Gregory C. Johnson, Steven A. Ahlstedt, and Joseph F. Connell

Free on application to the

Information Services Box 25286 Federal Center Denver, CO 80225

CONTENTS

Ground-Water Highlights............................................................................................................... 2

INTRODUCTION TO THE UPPER TENNESSEE RIVER BASIN....................................................... 3 MAJOR FINDINGS ............................................................................................................................. 7 Bacteria in the Upper Tennessee River Basin .............................................................................. 7

Toxic Spills and Releases ............................................................................................................. 22

STUDY UNIT DESIGN ....................................................................................................................... 23 GLOSSARY ........................................................................................................................................ 25 REFERENCES ................................................................................................................................... 26 APPENDIX—WATER-QUALITY DATA FROM THE UPPER TENNESSEE RIVER BASIN IN A NATIONAL CONTEXT ........................................................................................... 27

NATIONAL WATER-QUALITY ASSESSMENT PROGRAM

THIS REPORT summarizes major findings about water quality in the Upper Tennessee River Basin that emerged from an assessment conducted between 1994 and 1998 by the U.S. Geological Survey (USGS) National Water-Quality Assessment (NAWQA) Program. Water quality is discussed in terms of local and regional issues and compared to conditions found in all 36 NAWQA study areas, called Study Units, assessed to date. Findings are also explained in the context of selected national benchmarks, such as those for drinking-water quality and the protection of aquatic organisms. The NAWQA Program was not intended to assess the quality of the Nation’s drinking water, such as by monitoring water from household taps. Rather, the assessments focus on the quality of the resource itself, thereby complementing many ongoing Federal, State, and local drinking-water monitoring programs. The comparisons made in this report to drinking-water standards and guidelines are only in the context of the available untreated resource, Finally, this report includes information about the status of aquatic communities and the condition of in-stream habitats as elements of a complete water-quality assessment. Many topics covered in this report reflect the concerns of officials of State and Federal agencies, water-resource managers, and members of stakeholder groups who provided advice and input during the Upper Tennessee River Basin assessment. Basin residents who wish to know more about water quality in the areas where they live will find this report informative as well.

THE NAWQA PROGRAM seeks to improve scientific and public understanding of water quality in the Nation’s major river basins and ground-water systems. Better understanding facilitates effective resource managment, accurate identification of water-quality priorities, and successful development of strategies that protect and restore water quality. Guided by a nationally consistent study design and shaped by ongoing communication with local, State, and Federal agencies, NAWQA assessments support the investigation of local issues and trends while providing a firm foundation for understanding water quality at regional and national scales. The ability to integrate local and national scales of data collection and analysis is a unique feature of the USGS NAWQA Program. The Upper Tennessee River Basin Study Unit is one of 51 water-quality assessments initiated since 1991, when the U.S. Congress appropriated funds for the USGS to begin the NAWQA Program. As indicated on the map, 36 assessments have been completed, and 15 more assessments will conclude in 2001. Collectively, these assessments cover about one-half of the land area of the United States and include water resources that are available to more than 60 percent of the U.S. population.

SUMMARY OF MAJOR FINDINGS

Surface-Water Highlights

The Upper Tennessee River Basin is characterized by an abundance of surface water that usually meets existing guidelines for drinking-water supply, recreation, and the protection of aquatic life. Bacteria levels, however, frequently exceed State standards for contact recreation both in agricultural and urban areas. In addition, mixtures of pesticides were detected at 67 of the 74 stream sites sampled. No pesticide concentrations exceeded drinking-water standards, but standards have not been determined for 11 of the 31 compounds detected.

• Bacteria levels frequently exceeded State standards in agricultural streams and streams in urban areas. Runoff from pasture land and direct livestock access to streams contribute to elevated bacterial counts in agricultural streams. Aging wastewater infrastructures are the most likely cause of elevated bacteria counts in urban streams.
• Inputs from urban and agricultural land uses have increased nutrient levels in streams. Yields of total nitrogen in streams are correlated to agricultural inputs, such as animal waste and fertilizer applications, whereas yields of total phosphorus are correlated with wastewater discharges. Tributary reservoirs serve as effective sinks for both nitrogen and phosphorus species in the basin.
• Herbicides and herbicide degradates were detected in 98 percent of the 428 total stream-water samples collected but at levels within drinking-water standards and aquatic-life guidelines. Insecticides used on agricultural fields, gardens, and lawns were detected infrequently (less than 12 percent of samples) and were at levels within drinking-water standards. Concentrations exceeding aquatic-life guidelines were observed, however, for carbaryl, diazinon, and lindane.
• Contamination from previous industrial and mining activities persists in parts of the basin resulting in fish-consumption advisories for PCB’s (polychlorinated biphenyls), dioxin, and mercury in certain reservoirs and stream reaches. SVOC (semivolatile organic compounds) sediment concentrations exceeding aquatic-life guidelines were detected in some stream reaches draining coal mining areas.
• The Upper Tennessee River Basin is widely known for its aquatic diversity of fish and mussel species. While mussel populations are recovering in some parts of the basin, overall diversity is slowly declining.
• Releases and spills resulting in fish and mussel kills have occurred in many parts of the basin and pose a threat to isolated and endangered populations of aquatic species.

Trends in Stream-Water Quality

Because of water-treatment improvements, nitrogen and phosphorus levels for most of the streams in the Upper Tennessee River Basin remained unchanged or decreased from 1970 to 1993. Nitrogen concentrations, however, increased significantly for many streams in the Blue Ridge physiographic province because of nonurban residential development and aquaculture.

Trends in other water-quality constituents are difficult to assess because of changes in data-collection methods over time and an overall lack of data. Persistent organochlorine compounds such as DDE, a breakdown product of DDT, which was discontinued in 1973, and chlordane, which was discontinued in 1988, are still detected in fish tissues and bottom sediments in various parts of the basin.

Major Influences on Surface Waters

• Runoff from agricultural and urban areas
• Effluent from wastewater-treatment facilities
• Persistent sediment contamination
• Episodic spills and toxic releases

Ground-Water Highlights

Although ground-water use accounts for a little more than 3 percent of the total water use in the basin, over one-third of the population relies upon ground-water sources for drinking water. In the Upper Tennessee River Basin, ground-water studies focused on the carbonate rock formations of the Valley and Ridge physiographic province, which compose the most prolific aquifers in the basin and are the most susceptible to contamination. These aquifers typically provide water that meets all Federal and State drinking-water standards with the exceptions of nitrate and bacteria. Nitrate concentrations in domestic wells and springs used as drinking-water sources were within drinking-water standards and guidelines. Levels of nitrate exceeding drinking-water standards were detected only in shallow agricultural monitoring wells. Numerous pesticides and volatile organic compounds were detected in wells and springs, but none exceeded drinking-water standards.

• Bacteria levels exceeding finished drinking-water standards were detected in 11 of 30 wells used for untreated domestic drinking-water supply and in all 35 springs sampled. Bacteria levels in two springs exceeded State standards for recreation. Seventeen of the springs sampled are used for untreated drinking-water supplies.
• Nitrate was present in all domestic wells and springs but usually in concentrations well within the Federal drinking-water standard. Five of 30 monitoring wells that were installed adjacent to burley tobacco fields contained nitrate concentrations exceeding the drinking-water standard.
• Pesticides were detected in 40 percent of the agricultural wells, 43 percent of domestic water-supply wells, and 69 percent of the springs in relatively low concentrations. No pesticide concentrations exceeded drinking-water standards; however, 5 of the 18 compounds detected currently do not have standards. The most frequently detected pesticides were atrazine and metalaxyl (tobacco-specific) in the agricultural wells and atrazine, tebuthiuron, and prometon in domestic wells and springs.
• Volatile organic compounds were detected in 86 percent of the springs and 67 percent of the domestic wells sampled. Trichloromethane was the most frequently detected compound of the 28 volatile organic compounds that were detected; but carbon disulfide, propanone, and methylbenzene generally were detected in the highest concentrations. None of the volatile organic compounds exceeded drinking-water standards or guidelines, but only 12 of the 28 currently have standards.

Major Influences on Ground Water

• Agricultural and urban land uses
• Permeability of soils and aquifer materials
• Bedrock fracture patterns and karst features

INTRODUCTION TO THE UPPER TENNESSEE RIVER BASIN

The Upper Tennessee River Basin Study Unit encompasses about 21,390 square miles and includes the entire drainage area of the Tennessee River and its tributaries upstream from the USGS gaging station at Chattanooga, Tennessee. The study area includes parts of four States: Tennessee (11,500 square miles), North Carolina (5,480 square miles), Virginia (3,130 square miles), and Georgia (1,280 square miles). In 1990, the total population of the study area was about 2.4 million, of which about 1.6 million resided in the four metropolitan statistical areas of Chattanooga and Knoxville, Tennessee; Asheville, North Carolina; and the Tri-Cities area of Kingsport and Johnson City, Tennessee, and Bristol, Tennessee and Virginia.

Parts of three physiographic provinces–the Cumberland Plateau, Valley and Ridge, and Blue Ridge Provinces– compose the Upper Tennessee River Basin. Altitudes range from 621 feet above sea level at Chattanooga to 6,684 feet at Mount Mitchell, which is just northeast of Asheville, North Carolina, and is the highest point in the Eastern United States. The Study Unit contains some of the most rugged terrain in the Eastern United States, including the Great Smoky Mountains range. The crest of the Smoky Mountains exceeds 5,000 feet for 34 miles along the Tennessee-North Carolina State line, has 16 peaks that exceed 6,000 feet, and is the most massive mountain range east of the Mississippi River.

The region generally has a temperate climate; temperatures and annual precipitation totals largely are dependent on land-surface elevations. Average annual temperatures in the area generally decrease by about 3 degrees Fahrenheit for every 1,000-foot increase in elevation. Average annual precipitation ranges from about 40 inches in some low-lying, sheltered areas in the Valley and Ridge province to more than 90 inches at elevations over 6,000 feet. Precipitation generally is distributed evenly throughout the year with no distinct dry and wet seasons.(1)

Introduction to the Upper Tennessee River Basin

Forests cover more than 67 percent of the Study Unit (fig. 1) and five National Forests–Jefferson, Pisgah, Cherokee, Nantahala, and Chattahooche National Forests–wholly or partially lie within the basin. Agricultural land, predominantly pasture, is the second most common land use and accounts for more than 26 percent of the study area. Row crops account for only about 2.6 percent of the study area. Most of the agricultural land is located in the stream valleys and gently rolling parts of the Valley and Ridge physiographic province. The crests of steep ridges and more rugged areas of the basin remain forested. Less than 4.5 percent of the basin is developed. Row crops and developed areas, however, generally affect water-quality conditions much more than their small percentages would indicate.

Surface-Water Features

The most prominent surface-water features of the Upper Tennessee River Basin are the tributary and main-stem reservoirs constructed and maintained by the Tennessee Valley Authority (TVA) and sometimes referred to as the “Great Lakes of the South.” Four main-stem reservoirs are primarily flow-through systems that provide power generation and maintain navigational depths but provide little flood storage. These four reservoirs have a combined capacity of about 3.1 million acre-feet. Seventeen tributary reservoirs provide flood storage and power generation. These tributary reservoirs have a combined storage capacity of some 10 million acre-feet. An additional 17 privately owned and operated reservoirs also are located in the study area and have a combined storage capacity of about 0.6 million acre-feet.

Five major tributaries (fig. 2) account for about 86 percent of the annual mean discharge of 35,450 cubic feet per second at the Tennessee River at Chattanooga and over 87 percent of the total area of the upper Tennessee River Basin. The Clinch (4,413 square miles), Holston (3,776 square miles), French Broad (5,124 square miles), Little Tennessee (2,627 square miles), and Hiwassee (2,700 square miles) Rivers each exhibit distinctive climatic and runoff characteristics. Average annual precipitation in these river basins ranges from about 45 inches in the Holston River Basin to almost 60 inches in the Little Tennessee River Basin, which receives the highest rainfall in the continental United States outside of the Puget Sound area of

Washington State.(3) Average annual runoff totals have similar variations and range from about 18 inches in the Holston River Basin to more than 34 inches in the Little Tennessee River Basin.(4)

Water Use

In 1995, withdrawals of surface and ground water in the Upper Tennessee River Basin totaled about 4.8 billion gallons per day. Surface-water withdrawals for once-through cooling at thermoelectric plants accounted for about 3.5 billion gallons per day, or 73 percent of this total. Other uses (fig. 3) were commercial and industrial, 702 million gallons per day; public and domestic supply, 394 million gallons per day; agricultural, 203.3 million gallons per day: and mining, 10.4 million gallons per day, all of which were predominantly surface-water withdrawals.(5) A total of 897 facilities were permitted to discharge wastewater in 1995 to area streams.

Figure 3. Nonthermoelectric water use in the Upper Tennessee River Basin, 1995. (Thermoelectric water use accounted for 73 percent of the total water use.)

Total ground-water withdrawals in the basin for 1995 were about 138 million gallons per day and accounted for about 10.5 percent of the total nonthermoelectric water use in the basin. About 77 percent of the ground-water withdrawals were for public and domestic supply for over one-third of the basin’s population.

Hydrologic Conditions

Understanding hydrologic variations over time is necessary for assessing water-quality conditions as well as for providing a context with which to evaluate trends. Overall, rainfall during the data-collection period was about 10 percent greater than the long-term mean values. Most of the excess rainfall occurred in the northern part of the basin, as the Knoxville and Tri-Cities weather stations both recorded about 4 inches per year more than their long-term averages of 46.7 and 41.3 inches, respectively. During this same period, rainfall at Chattanooga averaged only about 1 inch per year more than the long-term average of 53.3 inches.(6)

Although precipitation usually is distributed relatively evenly throughout the year in the Upper Tennessee River Basin with no pronounced dry or wet seasons, two relatively dry periods occurred in the late summer and fall of 1997 and 1998. These periods are reflected in the rainfall departures in figure 4 and streamflow discharges in figure 5.

Ground-Water Resources

Ground water in the Upper Tennessee River Basin occurs almost exclusively in unconfined water-table conditions with no regional flow systems. Ground-water flow systems usually are less than 10 square miles in areal extent and are largely controlled by the bedrock geology (fig. 6) and thickness of overlying regolith.

The Cumberland Plateau is characterized by hard, relatively impermeable sandstone of Pennsylvanian age generally overlain by thin soils. Well yields generally range from 5 to 50 gallons per minute from fractures, faults, and bedding-plane openings. Over much of the province, however, reliable ground-water supplies are not obtainable. Similarly, the Blue Ridge physiographic province is characterized by fractured crystalline igneous and metamorphic rock of low porosity and little storage capacity. Well yields depend upon interception of water-bearing fracture systems and usually range from 10 to 25 gallons of water per minute where available.

The Valley and Ridge physiographic province is underlain by folded and extensively faulted limestone, dolomite, shale, and sandstones that occur in long subparallel belts trending southwest to northeast. The principal water-bearing units are the carbonatebased dolomites and limestones, which provide water for many cities and industries. Yields generally range from

Figure 6. Ground-water availability is a function of surface geology in the Upper Tennessee River Basin.

Introduction to the Upper Tennessee River Basin

5 to 200 gallons per minute, but wells penetrating extensive solution features may yield as much as 2,000 gallons per minute.(7) Solution features, such as caves and sinkholes with their inherent permeability, make the Valley and Ridge carbonate aquifers the most susceptible in the basin to contamination.

Biological Diversity

The Upper Tennessee River Basin is noted nationally for its diversity of freshwater fishes and mussels. The basin provides habitat for 174 species of fish, including 25 species that are non-native.

Of the 149 fish species native to the Upper Tennessee River, 29 are found only in the Tennessee and adjacent Cumberland River Basins, and 15 are found only in the Upper Tennessee River. Fifteen fish species in the basin are federally listed as endangered or threatened and 50 species are listed under management categories used by the four States.

Most of the fish diversity in the basin is concentrated in the Valley and Ridge physiographic province, which includes 141 of the 149 native Upper Tennessee species, most notably in the Upper Clinch and lower Holston River Basins (fig. 7). The Clinch River alone is home to 126 Upper Tennessee River native species, 12 of which are federally protected and 41 of which are State listed. Four previously recorded fish species are no longer found in the Clinch River, the largest number of eliminated fish species for any Upper Tennessee drainage.

The Upper Tennessee River also includes one of the most diverse freshwater mussel fauna in the world with 85 different species having historically been recorded. Twenty-five of these species are no longer found in the basin, mostly because of habitat destruction associated with reservoir

impoundment, and 11 are now believed to be extinct. Of the 60 freshwater mussel species now found in the Upper Tennessee River Basin, 30 species are under Federal protection and 52 species are listed by the States.

As with fishes, most of the freshwater mussel diversity is associated with the Valley and Ridge physiographic province, especially the Clinch River system (fig. 8). The Clinch River is now home to about 52 species of a previously recorded total of 79. Of the current total, 28 are federally listed and 38 are listed by the States.

Home to more than 300 globally rare species, the Upper Clinch River system, which includes the Powell River, has attracted attention from a number of environmental organizations including the designation as one of the “Last Great Places” by the Nature Conservancy. The Clinch River system also is considered to be one of the more biologically threatened river systems in the country (fig. 9). Of the 178 freshwater fish and mussel species presently inhabiting the Clinch River Basin, more than onefourth are considered to be at-risk.(8)

Study Unit Design Focuses on Land Use.

Chemical and biological samples were collected from selected rivers and streams draining different land-use areas to assess overall quality as well as the effects of specific land uses. The study focused on agricultural land use and unregulated streams in the Valley and Ridge physiographic province. At Basic Fixed Sites, water samples were collected monthly and during storms to assess runoff conditions. Synoptic sites were sampled only once during periods of average flow.

Springs, domestic wells, and specifically installed agricultural monitoring wells were sampled to assess overall ground-water quality in the basin. Ground-water studies focused on the dolomite and limestone areas of the Valley and Ridge province, which provide the best aquifers and are the most susceptible areas in the basin to ground-water contamination. (See Study Unit Design, page 23, for details.)

MAJOR FINDINGS

Bacteria in the Upper Tennessee River Basin

Fecal indicator bacteria are the most frequent and widespread water-quality standard exceedances involving potential adverse effects to human health in the Upper Tennessee River Basin. The indicator bacteria themselves usually are harmless and easy to detect, but they are indicators of the presence of fecal material and have been shown to be associated with some waterborne disease-causing organisms. The presence of indicator bacteria, however, cannot be considered direct proof of any threat to human health, and research is underway to find better indicators.

Bacterial Counts Frequently Exceed Standards

The State of Tennessee’s current water-quality standards are based on a total fecal coliform level of 200 colonies per 100 milliliters of water, as a mean value.(9) This value is commonly exceeded in agricultural and urban streams in the Upper Tennessee River Basin (fig. 10). In agricultural areas, livestock waste is the most likely bacterial source both from allowing livestock direct access to streams and runoff from animal-waste areas. Bacterial counts generally increase during higher streamflows associated with runoff events in the agricultural areas (fig. 11).

Deteriorated and leaky sewage systems, faulty sewage treatment plants, urban runoff, and combined sewer overflow systems are among the sources of bacterial contamination in many urban streams. For example, all of the urban streams draining the central Knoxville, Tennessee, area regularly exceed bacterial standards because of widespread leakage from very old and deteriorating sewer systems in the older parts of the city. Replacement in 1998 of an obsolete combined sewer overflow system for one city neighborhood, however, has improved conditions for that neighborhood and adjacent parts of Fort Loudon Reservoir. These conditions highlight the continuing need for infrastructure improvements, especially in older urban areas.

Figure 10. Fecal coliform bacteria frequently exceed standards in Upper Tennessee River (UTEN) streams.

Figure 11. Fecal coliform counts vary with streamflow at Big Limestone Creek in Tennessee.

Bacteria Frequently Are Detected in Domestic Wells and Springs

A common misconception is that untreated ground water from wells and springs generally is safe for consumption because percolation through the soil removes most contaminants. While the soil can act as a natural filter, this does not guarantee the absence of contaminants. In fact, about half of the waterborne-disease outbreaks in the United States since 1900 have involved contaminated ground water.(11)

Ground-water systems such as the carbonate systems of the Upper Tennessee River Basin are particularly susceptible to contamination from surface sources. Ground-water flow paths in these systems usually are shallow, principally involving the upper 10 to 20 feet of highly fractured and heavily weathered rock. In addition, the common presence of bedrock outcrops, areas of thin overburden, and karst features such as sinkholes provide direct avenues for aquifer contamination (fig. 12). Other potential sources for bacterial contamination include faulty or poorly placed septic systems and poor well construction or sanitation practices.

For finished drinking water, the detection of as few as 4 coliform bacteria colonies per 100 milliliters (col/100 mL) or the detection of 1 col/100 mL of fecal coliform bacteria, or E. coli, warrants concern for human health.(12) Of 30 domestic wells used as sources for untreated drinking water, 11 (37 percent) exceeded the total coliform drinking-water standard and 9 (30 percent)

the E. coli drinking-water standard (fig. 13). The highest E. coli value detected was 1,600 col/100 mL.

Total coliform values for 35 springs sampled in the Upper Tennessee River Basin ranged from 10 to 1,900 col/100 mL and E. coli ranged from 0 to 660 col/100 mL. All of the springs tested exceeded drinking-water standards for total coliform bacteria, and 95 percent of the springs exceeded the E. coli standard. Two springs exceeded the E. coli body-contact standard of 126 col/100 mL. Sixteen of the 35 springs are used as domestic water supplies and others are used for filling water containers by the roadside with what usually is believed to be “clean mountain spring water.”

Nutrients in the Upper Tennessee River Basin

Nutrients are nitrogen and phosphorus compounds that are essential for plant growth. When found at elevated concentrations, however, nutrients can degrade water quality. The enrichment of a water body with nutrients, called eutrophication, can result in dense, rapidly multiplying growths, or blooms, of algal species and other nuisance aquatic plants. These can clog water intake pipes and filters and interfere with recreational activities, such as fishing, swimming, and boating. Subsequent decay of algal blooms can overload water bodies with oxidizable debris and result in foul odors, bad taste, and reduced dissolved oxygen levels, which are harmful to other aquatic life.(13)

Nutrients in the Upper Tennessee River Basin originate from point and nonpoint sources. Point sources are typically piped discharges from wastewater-treatment facilities and large urban and industrial stormwater systems. Nonpoint sources include stormwater runoff from urban and agricultural areas. In the Upper Tennessee River Basin, applications of synthetic fertilizers and manure are major sources.

Nutrient Loadings and Yields Vary among Upper Tennessee River Subbasins

Nutrient loadings in the Upper Tennessee River subbasins are primarily influenced by land use and streamflow conditions. Loads were estimated by using a constituent transport model and multiple regression to relate streamflow to the concentration of a water-quality constituent to derive loads.(14) Twenty-three stations with adequate streamflow and chemical records were used for nitrogen calculations and 20 for total phosphorus.

The highest yields in the study area for both nutrient species were detected in the French Broad River Basin, particularly the upstream portion that includes Asheville, North Carolina (figs. 14 and 15). The French Broad River, as a whole, accounted for about 40 percent of the 138,000 pounds per day (lb/d) average annual total nitrogen load(15) and about 25 percent of the 13,500 lb/d average annual total phosphorus load,(16) leaving the basin at Chattanooga, Tennessee. The Holston River Basin added another 22 percent of the total nitrogen load but only 8 percent of the total phosphorus load.

Figure 15. Mean annual total phosphorus yields between 1973 and 1993 were highest in the upper French Broad River Basin.

A combination of agricultural and urban runoff is probably responsible for conditions in the French Broad River. In addition, the French Broad River and its tributaries have a history of water-quality problems associated with industrial point-source discharges. These basins also had the highest yields and loadings in the Upper Tennessee River Basin for total ammonia and organic forms of nitrogen.

Nutrient loadings and yields generally were lowest in those basins with relatively low percentages of agricultural land use and at sites directly downstream from tributary reservoirs. The fate of nutrients in the reservoirs depends on the physical characteristics of the reservoir (volume, surface area, depth, and hydraulic retention time) and its trophic state.(17) The tributary reservoirs in the Upper Tennessee River Basin commonly function as sinks for nutrient species by providing a favorable environment for nitrogen transformation and by efficiently trapping both dissolved and sediment-bound phosphorus. Outflow loads of total phosphorus below Norris Lake on the Clinch River, for example, were 37 percent of the inflow load from the Clinch and Powell River Basins. Load estimates for the Holston River upstream and downstream from

Major Findings

Cherokee Reservoir similarly indicate that the reservoir traps about 46 percent of the incoming load of total phosphorus. In contrast, less trapping occurs in the main-stem reservoirs, which are predominantly flow-through systems with limited storage capacity and relatively short residence times. Outflow phosphorus loads downstream from Chickamauga and Watts Bar Reservoirs significantly exceeded the inflow loads from upstream drainages. The increased loads can be attributed to low rates of trapping as well as additional input from ungaged areas adjacent to the reservoirs.(16)

Nutrient Concentrations and Yields Vary with Land Use

The relation between total nitrogen concentrations and land-use percentages was investigated for 87 sites in the Upper Tennessee River Basin and was found to be statistically significant. Stations in forested watersheds had the lowest concentrations of total nitrogen, whereas stations in agricultural areas had the highest. Concentrations of nitrogen in urban and mixed land-use areas were significantly greater than forested watersheds but were somewhat less than nitrogen concentrations in agricultural watersheds. Total nitrogen concentrations tended to increase with increased development whether agricultural or urban (fig.16).(15)

Nitrogen sources also were investigated by using regression analysis between annual basin yields and total annual inputs from fertilizer, animal waste, wastewater discharges, and atmospheric deposition. For total nitrogen, basin yields significantly and positively correlated with agricultural inputs but only weakly correlated with wastewater discharges and atmospheric inputs. This tends to identify agricultural land use as the major contributor to annual instream nitrogen yields.(18)

The relation between total phosphorus concentrations and land-use percentages also were investigated for 83

Figure 16. Median total nitrogen concentrations can be related to (A) agricultural, and (B) urban land uses.

Figure 17. Median total phosphorus concentrations can be related to (A) agricultural and (B) urban land uses.

sites in the Upper Tennessee River Basin. Although the relation was not quite as clear as with nitrogen, statistically significant increases in total phosphorus concentrations also accompanied increased development whether urban or agricultural (fig. 17). As with total nitrogen, the lowest phosphorus concentrations were detected at sites in predominantly forested watersheds, whereas sites in urban and agricultural areas had the highest phosphorus concentrations.(16)

Phosphorus sources also were investigated by using calculated basin yields and total annual inputs from fertilizer,

animal waste, wastewater discharges, and the atmosphere. Phosphorus yields were found to strongly correlate with wastewater discharges but not with the agriculturally related input categories. This suggests that wastewater discharges may account for most of the total phosphorus load in basin streams (J.F. Connell, U.S. Geological Survey, written comun., October 20, 2000). Agriculturally applied phosphorus may be assimilated quickly by area soils thereby reaching area streams slowly if at all.

Nutrient Concentrations in Upper Tennessee River Basin Surface Waters Generally Are Lower Than National Median Concentrations

Although nutrient concentrations and loadings are a concern in parts of the Upper Tennessee River Basin, concentrations generally are low for most area subbasins when compared with national averages. Mean total nitrogen concentrations exceeded or equaled the national median values only for three agricultural sites: Big Limestone Creek (83 percent agricultural), Copper Creek (51 percent agricultural), and the Nolichucky River (39 percent agricultural). Similar results

Nitrogen Species Changed by Wastewater Treatment

Prior to the widespread implementation of wastewater treatment, nitrogen loadings for most Upper Tennessee River Basin streams primarily consisted of reduced species such as ammonia and various organic forms. These nitrogen species generally are undesirable in surface water because of associated color changes and decreases in dissolved oxygen levels. In addition, under certain conditions, ammonia nitrogen can be highly toxic to aquatic life. Wastewater-treatment facilities convert these undesirable forms to the oxidized species, nitrite and nitrate.

At the Tennessee River at Chattanooga, Tennessee, as with most major streams in the Upper Tennessee River Basin, the ratio of reduced to oxidized nitrogen species began to change in the late 1970s (fig. 18), corresponding to were obtained for total phosphorus at Big Limestone Creek and the Nolichucky River, but the French Broad River flowing into Tennessee from North Carolina also exceeded the national median value. Although relatively low, mean total phosphorus concentrations at most sites exceeded the U.S. Environmental Protection Agency (USEPA) goal of 0.05 mg/L total phosphorus for surface water entering reservoirs.

the implementation of wastewater-treatment facilities. By about 1983, the oxidized nitrogen species, nitrate and nitrite, became the predominant forms of nitrogen discharged from the basin, a trend which has continued to the present.

Loading Trends Increase in Parts of the Upper Tennessee Basin

Trend analyses for 56 stations using the seasonal Kendall statistical analysis test indicated significant increases in total nitrogen at seven sites in the Upper Tennessee River Basin and significant decreases at eight sites (fig. 19). Sites showing decreases were all on relatively major streams (average drainage area, 2,600 square miles) or below major impoundments. Of the seven sites showing increases, six are in the Blue Ridge physiographic province and six drain basins with forests accounting for more than 75 percent of the total land use. The exception is Beaver Creek, which drains the Bristol, Tennessee and Virginia, urban area in the Valley and Ridge Province. The average area of basins showing nitrogen increases was only 276 square miles.(15)

Of the seven sites showing increases, five are in the Blue Ridge in North Carolina–two sites on the French Broad River and one each on the Little Tennessee River and tributaries to the Hiwassee and Pigeon Rivers. Much of this area is undergoing nonurban residential development in the form of vacation homes. Nitrogen loads are probably increased by the sewage and fertilizer use associated with this development.

Similar trend analyses for 42 sites to detect changes in total phosphorus concentrations yielded only one site with significant increases (fig. 20). West Chickamauga Creek, which drains a major industrial and urban setting, showed high concentrations for the entire period of record. Most (33) sites showed no trend, and eight sites showed significant decreases. These sites are dominated for the most part by pasture and forest; however, three sites are downstream from major wastewater discharges.(16) For sites in these more urbanized basins, improvements in wastewater-treatment processes are clearly responsible for the downward phosphorus trends.

Nutrient Concentrations Generally Are Low in Upper Tennessee River Basin Ground Water

All of the nutrients measured in the Upper Tennessee River Basin ground water were relatively low, as is usually typical of ground water. Most nutrient species are retained by soil particles or organic matter, taken up by plants, or utilized by soil bacteria and never enter the ground-water flow system. Exceptions are the nitrate and ammonia forms of nitrogen; however, only nitrate has a drinking-water standard, which is 10 mg/L. Drinking water containing nitrate concentrations higher than the standard can cause methemoglobinemia, a life-threatening illness in infants.

Nitrate was present in all wells and springs sampled in the Upper Tennessee River Basin but usually at concentrations of 3 mg/L or less. This included all of the 30 domestic wells used for drinking-water supply that were sampled and the 35 springs sampled across the basin. The median nitrate concentration for domestic wells was 0.59 mg/L, slightly more than the 25th percentile value nationally; the median nitrate concentration for springs was 1.16 mg/L, which was significantly lower than the national 50th percentile. The higher concentrations detected in springs most likely reflect the predominance of relatively short ground-water flow paths associated with localized recharge and runoff. No nitrate concentrations in excess of the 10-mg/L standard were detected in any domestic wells or springs. Nitrate concentrations in excess of the 10 mg/L standard were detected in 5 of the 30 wells installed during the study period to monitor shallow ground-water quality under and adjacent to tobacco fields. Tobacco is the main cash crop in the Upper Tennessee River Basin and is usually grown in small but intensively fertilized and cultivated plots. In general, fertilizer applications for tobacco cultivation are much greater than for any other row-type crop raised in the Upper Tennessee River Basin.

The median nitrate concentration in the shallow agricultural monitoring wells, however, was 0.68 mg/L–only slightly more than the median concentration for domestic wells and the national 25th percentile. Among the concentrations found nationally for agricultural and urban land uses, this value falls in the lower end of the medium range as shown in the accompanying figure.

The results indicate that nitrate contamination of extensive areas of ground water in the Upper Tennessee River Basin is very unlikely. High nitrate concentrations relative to the 10 mg/L drinking-water standard were detected only in shallow ground water directly under heavily fertilized tobacco plots. Tobacco fields typically cover only about 2 acres and are widely scattered across the study area. The potential for nitrate contamination of drinking-water sources is, therefore, very low outside of the immediate vicinity of tobacco fields.

Pesticides in the Upper Tennessee River Basin

Pesticides are widely used in the Upper Tennessee River Basin to control insects, fungi, weeds, and other undesirable organisms. These compounds vary in their toxicity, persistence in the environment, and transport characteristics. Use of some of the more persistent organochlorine compounds, such as DDT, chlordane, dieldrin, and aldrin has been discontinued in the United States, but their residues are still detected in the environment. Although pesticides usually are applied to specific areas and directed at specific organisms, these compounds often become widely distributed and pose hazards to nontarget organisms. Of 18 sites sampled for organochlorine residues in bottom material and biota in the Upper Tennessee River Basin, chlordane was detected at three sites and dieldrin and DDT-related residues at two sites.

Pesticide use in the Upper Tennessee River Basin is primarily for agricultural purposes. Herbicides, including atrazine and its degradation product, deethylatrazine, had some of the highest application rates and were also among the most frequently detected pesticides in the basin. Herbicides were detected in 98 percent of the 428 surface-water samples collected; atrazine was found in 91 percent and deethylatrazine in 86 percent. Metolachlor and

simazine were detected in 62 and 40 percent, respectively. Tebuthiuron and prometon, which are used most commonly in noncrop areas, were also among the most frequently detected herbicides (in 58 and 31 percent of the samples collected, respectively). The most frequently detected insecticides were diazinon (12 percent), carbaryl (10 percent), and chlorpyrifos (10 percent), all of which are used on a variety of crops to control pests.

Detection frequencies for 27 pesticides detected at 3 intensively sampled agricultural sites in the Upper Tennessee River Basin (fig. 21) generally illustrate the results obtained at all 13 Basic Fixed Sites from which surface-water samples were collected. Overall, a total of 32 pesticides were detected. Chlorothalonil, alpha-BHC, and terbacil each were detected once and ethoprop was detected twice.

Some differences among the three sites are notable and probably reflect different agricultural practices and hydrologic conditions. For example, at the Nolichucky River site, compounds generally not found at other sites such as cyanazine, alachlor, DCPA, metribuzin, bromacil, and diazinon, were detected. Molinate, trifluralin, and p,p’-DDE were detected only at the Copper Creek site, which also had a significantly higher frequency of detection for tebuthiuron. Pesticide detection frequencies at Big Limestone Creek and the Nolichucky River were, as expected, similar for several compounds

Figure 21. Pesticide detections at three agriculturally dominated sites followed similar patterns.

. including metolachlor, simazine, prometon, and napropamide. Big Limestone Creek is a tributary to the Nolichucky River, and both drain the same general agriculturally dominated area. The Big Limestone Creek drainage basin, however, contains more dairy operations than other parts of the Nolichucky drainage basin, which may account for some of the differences between the two sites.

Mixtures of Pesticides Are Common

Pesticides were seldom detected alone in surface-water samples and usually occurred as mixtures of several compounds. Generally, the effects of pesticide mixtures on biota or humans are not included in water-quality criteria, which are most commonly based on single-species, single-chemical toxicity tests conducted under laboratory conditions. As a result, potential adverse effects on biota may be underestimated.

Of the 163 samples collected at the three intensive sites, only 2 samples at Copper Creek contained only one detectable pesticide compound, and only 5 total samples contained only two compounds (fig. 22). Among the intensively sampled sites, samples from the Nolichucky River at Lowlands, Tennessee, generally contained more detectable pesticide compounds than samples from the other sites, but usually at lower concentrations. This reflects the larger drainage area of the Nolichucky River (1,687 square miles) as compared to the drainage areas of the other intensive sites (79 and 106 square miles for Big Limestone and Copper Creeks, respectively). Similarly, more pesticides also were detected in samples from Big Limestone Creek, which has a larger percentage of agricultural land use and a greater variety of crops than the Copper Creek Basin in Virginia.

Peak Pesticide Concentrations Are Seasonal

Pesticide concentrations were found to be seasonal and closely related to land use. The highest concentrations occurred in the more heavily agricultural basins in late spring and early summer, coinciding with crop applications. Results of weekly sampling results at the three intensively sampled agricultural sites illustrate the seasonality and short-lived nature of the peak concentrations in streams draining agricultural areas (fig. 23). Peak concentrations coincided with the first substantial runoff event following agricultural applications in May 1996, after which concentrations declined relatively rapidly to near-background levels. Less frequent sampling would have made it less likely to have noted the existence of the peaks. Because these streams are “flashy” in that peak discharges come and go very quickly, it is possible that even higher concentrations can occur for short periods of time. Seasonality also was evident at sites not characterized or directly influenced by intense agricultural activities. Atrazine and metolachlor concentrations at Clear Creek at Lilly Bridge, a predominantly forested watershed and part of the Obed National Wild and Scenic River watershed, also showed a distinct seasonality but with much lower concentrations (fig. 24). The seasonal pattern at this site is more gradual, suggesting atmospheric input more than runoff from agricultural activity.

Major Findings

Although most of the water samples collected contained detectable concentrations of one or more pesticides, no concentrations exceeded any drinking-water standards or guidelines. Only 20 of the 31 pesticides detected, however, have established guidelines. Of the 15 compounds that have aquatic-life guidelines, four were detected at concentrations higher than the guidelines. Carbaryl concentrations in excess of the 0.20- g/L (micrograms per liter) aquatic-life criterion were found in four samples—two each from the Guest River near Millers Yard, Virginia, and the Nolichucky River at Lowlands, Tennessee (fig. 25). Lindane, an organochlorine used primarily for the protection of tobacco transplants, was above the 0.01-μg/L criterion in three samples from three different sites, two of which were in the same subbasin - Little Limestone Creek and the Nolichucky River at Lowlands, Tennessee.

Some Pesticides Were Detected More Frequently in the Upper

Three herbicides consistently were detected more frequently in the Upper Tennessee River Basin than in other basins across the Nation. Atrazine and deethylatrazine were detected in 99 and 98 percent, respectively, of samples from agricultural basins in the Upper Tennessee River Basin and in 94 and 95 percent, respectively, of samples from mixed land-use basins - significantly more frequently than the national averages of about 80 and 60 percent, respectively. Tebuthiuron also was detected in about 60 percent of the Upper Tennessee River

Figure 25. Pesticide concentrations, in micrograms per liter (μg/L), infrequently exceeded aquatic-life criteria in the Upper Tennessee River Basin, 1996-98.

An atrazine concentration higher than the 0.18-μg/L criterion(20) also was detected in one sample taken at the Nolichucky River at Lowlands, Tennessee, in May 1996. This was the only criterion exceedance noted for any herbicide even though herbicides were detected much more frequently than the other

Tennessee River Basin Than Nationally

Basin samples as opposed to an overall average of about 20 percent nationally. Detection frequencies for most of the other herbicides probably reflect different herbicide-use patterns in the Upper Tennessee River Basin resulting from particular crop patterns. The three most commonly detected insecticides in the Upper Tennessee River Basin - diazinon, carbaryl, and chlorpyrifos - were detected less frequently than the national averages in all land-use categories. pesticide types. One sample collected at the Guest River near Millers Yard, Virginia, contained a diazinon concentration that was not only greater than the aquatic-life guideline of 0.08 μg/L but approached the USEPA lifetime health advisory level of 0.60 μg/L for drinking water.

Pesticides were detected in Upper Tennessee River Basin ground-water samples more often than not, but generally at concentrations less than 0.01 g/L. Pesticide concentrations in ground water did not exceed any drinking-water standards or guidelines. Usually, however, pesticides occur in mixtures for which criteria are not available. In addition, 5 of the 11 pesticides detected have no established guidelines or criteria.

Pesticides were detected in springs significantly more often and in more pesticide detections per sample than in other ground-water sources sampled (fig. 26). This probably reflects the greater vulnerability of springs to surface contamination either from the immediate area or karst features in the carbonate bedrocks. More frequent detections also may reflect the larger drainage areas from which springs capture ground water as opposed to wells. Of the 35 springs sampled, 24 (69 percent) contained detectable pesticide concentrations, and 12 (34 percent) contained detectable quantities of three or more different compounds. Detection frequencies in agricultural and domestic wells, by contrast, were significantly lower and similar to one another; 12 of 30 (40 percent) agricultural wells and 13 of 30 (43 percent) domestic wells contained detectable pesticide concentrations. Of these detections, only three (10 percent) samples from agricultural wells had detections of three or more pesticides. Eight (27 percent) domestic wells, however, had detections of three or more compounds.

Figure 26. Pesticides were detected at low concentrations in Upper Tennessee River Basin ground water.

Atrazine and its degradation product, deethylatrazine, were the pesticides most commonly detected in all ground-water samples but were detected twice as frequently in springs as in other ground-water sources (fig. 27). Tebuthiuron, the third most frequently detected pesticide, also was detected more than twice as frequently in springs as in domestic wells. The different pesticide mixtures typical of the agricultural wells sampled reflect the focus on tobacco in this phase of the study. In general, a different suite of pesticides are used for tobacco than for most other crops. For example, atrazine and other broadleaf herbicides are toxic to tobacco.

Volatile Organic Compounds Were Frequently Detected in Ground Water

Ground-water samples were collected from 30 domestic wells and 35 springs tapping carbonate strata in the Upper Tennessee River Basin. Volatile organic compounds (VOCs) were detected in most of the ground-water samples (fig. 28) but generally at very low concentrations–often in orders of magnitude below the established reporting limit. Twenty-eight different VOCs were detected during sampling, 12 of which have drinking-water standards. No measured concentrations, however, exceeded these standards.

VOCs were detected more frequently in springs (86 percent) than in domestic wells (67 percent) and generally at slightly higher concentrations. Of the 20 samples with one or more concentrations greater than 0.1 μg/L, 14 were taken from springs and only 6 from wells. Similarly, of the 28 compounds detected, 22 were detected in spring samples and only 18 were detected in domestic wells.

The most frequently detected VOCs were trichloromethane (51 percent), chloromethane (28 percent), styrene (23 percent), tetrachloroethane (18 percent), carbon disulfide (11 percent), and trichloroethene (9 percent). The remaining 22 compounds were detected in three or fewer samples (less than 5 percent).

Other than the greater detection frequencies for spring samples, no areal or other occurrence patterns could be found. As is the case nationally, the source for many of the most common VOCs detected in ground water, such as trichloromethane, is unclear. The greater occurrence of detections in springs as well as the widespread but random pattern of occurrence suggests the possibility of atmospheric origins, but no definite source can be identified at present.

Figure 28. Volatile organic compounds (VOCs) are often detected in Upper Tennessee River Basin ground water.

Upper Tennessee River Basin and National VOC Detection Frequencies Are Similar

Detection frequencies in Upper Tennessee River Basin wells for the 10 most commonly detected VOCs nationally were similar to national detection frequencies found for ambient ground water in all land-use settings. All compounds were assessed at a common detection level of 0.1 μg/L. Trichloromethane was the most commonly detected compound nationally as well as in the Upper Tennessee River Basin but typically was detected at concentrations far below drinking-water standards. The results are consistent with the mixed urban and rural land uses surrounding most Upper Tennessee River Basin ground-water sites.

Water-Quality Influences of Industry and Mining

Industrial and mining activities prior to the passage of the Clean Water Act in 1972 have left a legacy of contaminated sediment that continues to affect water quality in parts of the Upper Tennessee River Basin. The most widespread contaminants are PCBs (polychlorinated biphenyls) and mercury, mostly from industrial activities dating from 1950 to1972. Sources for some of the other contaminants, however, such as those affecting the Pigeon and Ocoee Rivers date back as far as 1908 and 1843, respectively.

Mercury in the North Fork Holston River is a result of the operation of a chlor-alkali plant on the banks of the river from 1950 through 1971. An estimated 75 pounds of mercury per day were discharged either directly to the river or into unlined holding ponds along the riverbank.(21) Although soils at the site have been remediated, the site continues to discharge mercury.(22) Bed-sediment and tissue samples taken from the Holston River system (fig. 29) were the only samples taken during the study that were above the Canadian guideline for aquatic-life protection (0.486 micrograms per gram total mercury). Although tissue samples in the main-stem Holston River site at Surgoinsville were free of mercury, the bed-sediment results suggest that mercury may be migrating farther downstream than previously thought and may eventually reach Cherokee Reservoir.

Mercury is also a major contaminant in the drainages downstream from the Department of Energy’s 35,585-acre Oak Ridge Reservation (ORR), such as East Fork Poplar Creek, the White Oak Creek watershed, and the lower Clinch River - Watts Bar Reservoir. The ORR, established in 1942 as part of the Manhattan Project to develop the atomic bomb, encompasses three major facilities — X–10, originally for weapons research but now Oak Ridge National Laboratory (ORNL); Y–12, for the fabrication of nuclear weapons components; and K–25, for uranium enrichment by gaseous diffusion. As a result of these operations, about 527 sites covering approximately 15 percent of the total ORR area have been identified as contaminated with metals, including mercury, radionuclides, a variety of VOCs, and nitrates.(23)

Most of the contamination has remained confined within the ORR, which was added in its entirety to USEPA’s National Priorities List in 1989. A number of contaminants, most notably mercury, PCBs, and cesium-137, however, have migrated to downstream areas. The State of Tennessee has posted a fish-consumption advisory for ORR drainages as wells as Watts Bar Reservoir as a result of bioaccumulation of mercury and PCBs in some fish species.

A 1983 inventory estimated that about 2 million pounds (1,088 metric tons) of mercury was ‘lost’ from operations related to thermonuclear bomb development on the ORR.(24) Most of this mercury is believed to have volatilized into the atmosphere, but much remains within ORR facilities and in Watts Bar Reservoir sediments. Analyses of sediment cores indicate that the highest discharges of mercury and cesium-137 occurred during the 1950s, and that about 76 metric tons of mercury has accumulated in Watts Bar sediments. About 91 percent of the 335

Major Findings

curies of cesium-137 released from the ORR have also been retained by the lake sediments. The concentrations detected are not believed to pose an imminent human health risk, especially if the deep sediments are not disturbed.(25)

Mining of the massive sulfide deposits in the Copper Basin along the Ocoee River began in 1843. Copper was the primary metal extracted, but iron, sulfur, zinc, and small amounts of gold and silver also were produced. Before 1900, Copper Basin was the largest metal-mining district in the Southeast. The last mine was closed in 1987.(26)

High concentrations of sulfur dioxide produced by smelting operations devastated the surrounding environment, resulting in a “moonscape” of about 25 square miles. Erosion of the area resulted in high sediment and associated metal loads to area streams. Although thousands of acres have been revegetated and the landscape is being slowly transformed back to forest, relatively high metal concentrations remain in the upper reaches of Parksville Reservoir and the Ocoee River.

Discharge of essentially untreated paper-mill effluent to the Pigeon River began in early 1908 and continued until plant improvements were instituted in the 1990s. Dioxins were first detected in fish samples from the river in 1988 (dioxin detection methods were not available until 1985) and became an immediate priority with respect to human health effects. Dioxins have not been detected in recent samples, including bed-sediment and tissue samples taken during the Upper Tennessee NAWQA study. The State of Tennessee, however, continues a precautionary fish-consumption advisory for the Tennessee portion of the river.

Even though discussions regarding the Pigeon River continue between the States of Tennessee and North Carolina, all parties agree that conditions have improved significantly. Once nearly devoid of aquatic life, benthic invertebrate and fish populations in the

Figure 30. Relatively high polycyclic aromatic hydrocarbon (PAH) concentrations, in micrograms per kilogram, are common in bed sediments in the upper Clinch River Basin.

Tennessee portion of the Pigeon River are showing signs of recovery. Waterville Lake, however, still retains tons of contaminated sediments deposited since the dam became operational in 1930, and these sediments remain a potential source of dioxin and other contaminants.

Polycyclic aromatic hydrocarbons (PAHs) commonly are detected as pollutants in soils and sediments, occur naturally in crude oil and coal, and also can result from the incomplete combustion of fossil fuels and forest fires.(28) In the upper Clinch River Basin, PAH concentrations reflect the presence of coal fines from upstream mining activities.

Twenty-nine PAHs were found in upper Clinch River bed-sediment samples and, with only a few exceptions, were not detected in the 12 samples taken from other parts of the Upper Tennessee Basin. Although PAHs are known to be toxic to fish, mussels, and aquatic insects, sediment-quality guidelines for the protection of aquatic life have been established for only 12 of the compounds detected. Of these, only two compounds – naphthalene and phenanthrene – exceeded their respective Canadian probable-effect levels of 391 μg/kg (micrograms per kilogram) and 515 μg/kg (fig. 30). The probable-effect levels define concentrations above which adverse effects are expected. A third compound, benzo(a)anthracene, occurred in concentrations very near its guideline of 385 μg/kg, and a number of compounds lacking guidelines were found at concentrations of 1,000 μg/kg or greater.

The highest concentrations generally follow the results for naphthalene and phenanthrene and occurred in the major river sites nearest, on a relative basis, to upstream mining activities. For example, concentrations at the Powell River and Pendleton Island sites exceeded those found at the Clinch River near Tazewell, which is farther removed from active mining in terms of river miles. Higher gradients and water velocities in the tributaries to the major streams prevent the accumulation of fine-grained sediment and coal fines. The main river channels, however, contain large pools and backwater areas where fine-grained material and associated constituents are deposited.

Freshwater Mussels in the Clinch and Powell Rivers

Freshwater mussel species diversity has been slowly declining in the Clinch and Powell Rivers of Tennessee and Virginia over the past 100 years. The numbers of mussel species found in these rivers are shown in figure 31 for selected periods of time and illustrate the long-term trend in loss of species diversity. The numbers do not precisely show numbers of species lost but reflect difficulties in finding specimens as species decline and, in some cases, difficulty with basin access. For example, prior to 1915, the upper parts of the river basins were inaccessible and remained unsurveyed.

Although some forms were lost, survey results from 1963 to 1971 indicate that the fauna survived TVA impoundment largely intact. Mussel declines became apparent, however, in the mid-1970’s, and by that time many previously common mussel species had become rare, extirpated, or extinct.

Upper Tennessee River Biological Communities in a National Context

Three biological indicators, which typically respond to changes in stream degradation, illustrate the relation of Upper Tennessee River Basin sites to the overall range of NAWQA sites nationwide. For all indicators, higher values suggest a more degraded stream site.

Algal status focuses on the changes in the percentage of certain algae in response to increasing siltation.Within the Upper Tennessee River Basin, the only sites in the highest 25 percent nationally are Big Limestone Creek, which drains predominantly agricultural land use, and the Pigeon River, which has been heavily affected by industrial wastes.

Invertebrate status is the average of 11 invertebrate (primarily insects, worms, crayfish, clams) metrics that summarize changes in richness, tolerance, trophic conditions, and dominance commonly associated with water-quality degradation. Among the Upper Tennessee River Basin sites, the two that rank highest on the index are the Pigeon and French Broad Rivers. The Pigeon River is recovering from decades of receiving industrial wastes. The French Broad River is principally affected by urban development in the Asheville, North Carolina, area and agriculture in the lower part of the basin.

Fish status is the sum of scores of four fish metrics (percentage of tolerant, omnivorous, non-native individuals, and percentage of individuals with external anomalies) that tend to increase in association with water-quality degradation. The Holston River at Surgoinsville, Tennessee, which ranked highest on this index, is characterized by relatively high concentrations of mercury and copper in bed sediments, probably derived from upstream industrial activities.

The greatest declines in mussel abundance occurred during the record drought from 1983 to 1988 (fig. 32). Since that time, the Clinch River in Tennessee has shown remarkable recovery, both in mussel densities and species numbers. The Virginia parts of the Clinch and the Powell Rivers, however, have recovered to a only a little more than half the densities recorded in 1979, mostly reflecting recovery of the three most abundant species. Most of the rare and more sensitive species continue to decline in the Powell River and in the Virginia part of the Clinch River.(29)

Toxic Spills and Releases

The NAWQA Program, like most water-quality assessments, is designed to gather information on general water-quality conditions and analyze problems that tend to be chronic as opposed to episodic. Even though the NAWQA Program provides for sampling during storm events in order to achieve a more complete “picture” of water-quality conditions, detection of every instance of water contamnation is clearly beyond the program’s defined scope. In general, this is true of every other ongoing State or Federal water-quality assessment.

In late May 1996, however, a toxic release was recorded at the Big Limestone Creek site (fig. 33, number 8) that resulted in a fishkill over several miles in the lower end of the stream. The apparent cause was excessive ammonia concentrations that were traced to agricultural activities upstream. If not for the sampling activity being conducted at the site, the kill most likely would have gone unreported. Given the relatively remote nature of many biologically diverse stream reaches in the Upper Tennessee River Basin, it is possible that many similar episodes go unreported as well.

The number of relatively rare and threatened aquatic species in the Upper Tennessee River Basin make accidental spills and releases a particular concern in parts of the basin. Habitat modifications resulting from human activities, such as impoundments and pollution, have restricted the greatest numbers and variety of aquatic fauna to only a few tributaries.(32) In addition, impoundments have effectively separated once contiguous biological communities into smaller, more vulnerable subunits.

The upper Clinch and Powell watersheds are home to the most diverse fish and mussel fauna in the Upper Tennessee River Basin. These two subbasins are effectively separated from biological interaction, however, by Norris Lake and are very vulnerable to coal-

fine spills from numerous active and abandoned mining sites in their headwaters. At least five coal-fine spills occurred during the 1995–99 study period (G. Heffinger, U.S Fish and Wildlife Service, written commun., April 17, 2000).

Mussel species generally are of the greatest concern because of their lack of mobility and the longer times typically required for populations to recover. For example, data collected in 1971 following a very large 1967 fly-ash spill in the Clinch River found that fish and aquatic insects were reestablished relatively quickly. Mussels, however, have yet to recolonize the 9- to 10-mile reach directly downstream from the spill site.(33)

STUDY UNIT DESIGN

Study designs for both ground-water and surface-water components focused principally on the Valley and Ridge province. The Valley and Ridge is home to the majority of the Study Unit population and is the most highly developed in terms of agriculture and urban land uses. Ground-water studies focused on the carbonatebased dolomites and limestones of the Valley and Ridge. These geologic units form the most prolific aquifers in the Upper Tennessee River Basin and also are the most susceptible to contamination because of their associated karst and solution features. Ground-water resources are very limited in the Blue Ridge and Cumberland Plateau provinces because of the relatively impermeable nature of the bedrock and the low waterstorage capacity of the thin soils that overlie the bedrock.

Surface-water studies focused on the unregulated portions of the Upper Tennessee River Basin principally in the Valley and Ridge province, which contains the most intense agricultural activity in the basin. Thirteen basic fixed stream-sampling sites were operated during the study to monitor water-quality conditions with time in various parts of the basin. Data-collection sites were selected to cover the major subbasins of the Upper Tennessee River and to encompass the major land uses. An additional 61 sites were sampled during the study as part of three synoptic networks designed to better describe areal water-quality variations of the subbasins. In keeping with the NAWQA multiple lines of evidence approach to describe water-quality conditions,(34) data-collection activities included water-column chemistry at all sites, bed-sediment and Asiatic clam tissue samples at Basic Fixed Sites, and stream ecological sampling (fish communities, benthic invertebrates, habitat, and algae) at all Basic Fixed Sites and most Synoptic sites.

SUMMARY OF DATA COLLECTION IN THE UPPER TENNESSEE RIVER BASIN, 1994–98

Study Sampling frequency Number of Types of sites sampled What data were collected and why component and period sites

GLOSSARY

Aquatic-life criteria—Water-quality guidelines for protection of

Aquifer—A water-bearing layer of soil, sand, gravel, or rock that

Basic Fixed Sites—Sites on streams at which streamflow is mea-

Bed sediment—The material that temporarily is stationary in the

Benthic invertebrates—Insects, mollusks, crustaceans, worms,

Constituent—A chemical or biological substance in water, sedi-

Contamination—Degradation of water quality compared to origi-

Degradation products—Compounds resulting from transforma-

Detection limit—The minimum concentration of a substance that

Discharge—Rate of fluid flow passing a given point at a given

Drainage area—The drainage area of a stream at a specified loca-

Indicator sites—Stream sampling sites located at outlets of drain-

Integrator or Mixed-use site—Stream sampling site located at an Intensive Fixed Sites—Basic Fixed Sites with increased sampling

Karst—A type of topography that results from dissolution and col-

Load—General term that refers to a material or constituent in solu-

Main stem—The principal course of a river or a stream. Metamorphic rock—Rock that has formed in the solid state in

Micrograms per liter (μg/L)—A unit expressing the concentra-

Milligrams per liter (mg/L)—A unit expressing the concentration

Nonpoint source—A pollution source that cannot be defined as

Point source—A source at a discrete location such as a discharge

Synoptic sites—Sites sampled during a short-term investigation of

Water-quality standards—State-adopted and U.S. Environmental

Water table—The point below the land surface where ground

Yield—The mass of material or constituent transported by a river

APPENDIX—WATER-QUALITY DATA FROM THE UPPER TENNESSEE RIVER BASIN IN A NATIONAL CONTEXT

Water-Quality Data in a National Context Water Quality in the Upper Tennessee River Basin

A COORDINATED EFFORT

Coordination with agencies and organizations in the Upper Tennessee River Basin was integral to the success of this water-quality assessment. We thank those who served as members of our liaison committee.

Federal Agencies Tennessee Valley Authority U.S. Fish and Wildlife Service National Park Service U.S. Department of Energy, Oak Ridge National Laboratory U.S. Environmental Protection Agency U.S. Forest Service U.S. Department of Agriculture, Natural Resources Conservation Service

State Agencies Tennessee Wildlife Resources Agency Tennessee Department of Environment and Conservation Tennessee Department of Agriculture North Carolina Department of Environment and Natural Resources North Carolina Wildlife Resources Commission Virginia Department of Environmental Quality Virginia Department of Game and Inland Fisheries Virginia Department of Mines, Minerals, and Energy

We thank the following individuals for contributing to this effort.

Edward Oaksford, Ben McPherson, Michael Woodside, Rebecca Deckard, and Sandra Cooper (USGS), Roberta Hylton (U.S. Fish and Wildlife Service), Karen Koehn and Celia Hampson (Knox County, Tennessee) for reviewing the report. Charles Saylor and Edward Scott (Tennessee Valley Authority) for assistance in site selection and data collection. The numerous property owners that allowed the use of their property by the USGS for access to specific stream reaches, the installation of monitoring wells, or the sampling of exisiting wells. Local Agencies Knox County, Tennessee City of Johnson City, Tennessee

Universities University of Tennessee Virginia Polytechnic and State University Tennessee Technological University

Other public and private organizations Southern Appalachian Man and the Biosphere Program Nature Conservancy

U.S. Geological Survey Circular 1205

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