However, in our region much of this rain is not pure. The effluent from coal-burning power plants combines with other effluents from industries, commercial incinerators, and the exhaust pipes of cars and trucks. Together, these chemical reactions combine with moisture in the air to form acid rain, ice, snow or fog. Measured on the pH scale (logarithmic: one unit increase equals a tenfold increase in acidity), natural rain has a pH of 5.0 to 5.6. The average pH of rain in the Smokies is 4.4, five to ten times more acidic. Precipitation of 3.5 has been recorded. Clouds in the Smoky Mountains have a pH as low as 1.8, considerably more acidic than lemon juice or vinegar.
Water that falls in the Mountains
Soil acts as a natural buffer against acid rain, neutralizing acidic compounds. But, the soil at high elevations in the Smoky Mountains is so saturated with deposited nitrogen that it cannot absorb any more. Thus, nitric acid is free to run off into streams or down into the water table. Similarly, the buffer capacity for sulfates will be overrun in a couple of decades.
In the last twenty years, acidity in the Park's most sensitive streams has increased threefold. Some of our region's higher elevations have the highest nitrate concentration of any streams in the U.S. that drain into undisturbed watersheds. Samples from streams indicate pH 4.9-5.1. If the level falls below 4.7, brook trout can die.
Acid rain also affects our trees. Red Spruce in the Park are dying because of an overdose of aluminum, which is naturally present in the soil, but unavailable to plants. The aluminum becomes mobilized by nitrates and sulfates, the main components of acid rain. Acid rains also weakens the resistance of trees, such as the Fraser Firs, to infections and pests. Acid rainwater also leaches nutrients from the leaves of plants. The dead forests on top of the highest peaks in the region, Mount LeConte (TN) and Mount Mitchell (NC) were still healthy as recently as the 1980's.
The damage done by acid deposition appears to be limited mostly to the high-lands. However, the current increase in acidity is spreading downwards and outwards year by year from the peaks.
Water that falls on Fields
Fecal mater from cattle is often washed into the streams and rivers, contam-inating them with viruses and bacteria. Algae proliferate from the nitrogen found in such feces. Other sources of nitrogen include: leaking septic tanks; urban sanitary sewers or sewage treatment plants and fertilizer; pesticides and herbicides from agricultural fields and suburban lawns. Algae deprive the water of oxygen in two ways: 1) they may absorb oxygen directly and 2) bacteria which work to decompose dead algae require oxygen. Low oxygen levels, prevalent in many TVA reservoirs, threaten fish and other aquatic forms of life.
Nutrient runoff into streams is made easier by the destruction of natural stream borders. Healthy streams in Southern Appalachia do not have bare, mown banks; they are lushly overhung by trees and bushes that provide homes for aquatic wildlife. Bare stream borders do not filter out contaminants, which can cause cancer and other maladies in aquatic organisms. Runoff can also cause increased turbu-lence, blocking vision, and siltation, clogging up the gills and filter-feeding apparati of many species. Destruction of sreamside vegetation contributes to water temperature increases, which motivates the growth of algae.
Water that falls on Asphalt
Urbanization causes more and more rain to fall on asphalt. Water that does not evaporate on hot asphalt mixes with road grit and the toxic effluents of leaky automobiles (such as antifreeze, brake fluid, gasoline and diesel fuel, grease, wind-shield washer fluid, transmission fluid, rubber from tires, and oil) causing a slippery and dangerous slurry. Rushing water picks up trash that people throw or drop on parking lots and roads as it travels through gutters, curbs and storm sewers. Ultimately all of it pours out untreated, directly into nearby rivers, streams or creeks.
Toxic materials are sometimes illegally dumped by negligent or unscrupulous businesses into storm drains. The sections of concrete pipes that compose the storm drains are in many places cracked and broken by tree roots, making it possible for substances to leak into the ground. During heavy rains this may permit the influx of sewage from sewers into storm drains. In this way, sewage and industrial wastes can end up untreated in rivers and streams.
Asphalt absorbs nothing. During a heavy rain, torrents of water quickly shed into nearby rivers and streams, increasing the frequency of damaging floods.
Swept by rainwater, trash moves downstream into rivers pooled by dams. It even-tually reaches reservoirs, where the water flow is slower, sinking to the bottom or accumulating on the shorelines of quiet bays. Trash accumulated behind dams is flushed through the dam's flood gates by TVA. Clean-up events organized by local communities, such as River Rescues, have gradually reduced visible litter in some areas.
The Old River
The land of the Upper Tennessee Valley is dominated by a remarkable series of parallel ridges, running northeast to southwest, with rivers and streams flowing in between. White settlers first called the Tennessee River the Tanasi. However, Native Americans called the river the Hogohegee, which means "the big river". Tanasi was an important Cherokee town. The site of this town, which gave the state and river its name, now lies in a watery grave beneath TVA's Tellico Reservoir.
The old Hogohegee River is almost entirely submerged; it is now seen only along portions of the Holston River. Colossal dams divide the modern Tennessee into a series of discontinuous steps, with bare, sunbleached limestone, called riprap, dumpedalong many shorelines to keep the fertile mud from falling in the water. Behind each dam, the river swells out and causes a permanent flood. Formerly fertile and productive farms lie entombed by toxic silt.
Soil erosion has resulted from eighteenth century logging, mining, construction and road building. Much of Tennessee's rich soil was flushed into creeks and rivers and is still making its way through the system.
Trapped behind TVA dams and retained by water reservoirs, silt coming down the river settles out as sediment. Eventually the reservoirs will be transformed to shallow lakes or streamcrossed wetlands. Because of the siltation several of TVA's smaller reservoirs are silted up and one, TVA's Nolichucky Reservoir can no longer produce power. Although TVA's larger reservoirs are in no immediate danger of reverting to wetlands, siltation does cause these reservoirs to grow continually wider and shallower, narrowing the ecologically important summer riparian zone and increasing turbidity (sediment) in the water. In the long run, reservoirs' capacity for flood control will diminish completely. Removing the silt would be prohibitively expensive.
Removing the silt would also create a huge hazardous waste disposal problem, since the silt has trapped an enormous quantity of garbage and toxic chemicals poured into the river through decades of industrial abuse. Most experts believe that there is no safe way to remove or clean the silt and that the safest thing to do is to let further layers accumulate over it until it is deeply buried.
PCB contamination is serious in many of the region's waterways, particularly Fort Loudon, Watts Bar, Tellico, Melton Hill, and Boone Reservoirs and at Chattanooga Creek. PCBs slowly make their way up in the food chain, stored in fatty tissues ("bioaccumulation"). As a result, dangerously high levels may be found in the largest aquatic predators, such as catfish and bass.
The bioregion's most dangerously contaminated silt occurs in the vicinity of the U.S. Department of Energy's Oak Ridge Reservation. White Oak Reservoir, which collects drainage from seven nuclear and chemical waste burial grounds on the reservation, is the most radioactive lake in the U.S.A. After the discovery of a radio-active "hotspot" in 1990, a seven-million-dollar dam was built in 1992 to prevent the radioactive sediment from further flowing into the Clinch River.
White Oak Creek and Poplar Creek, both of which empty into the Clinch River, are chief sources of radioactive and chemical outflow into the lower Clinch and Watts Bar Reservoir. The Department of Energy kept this from public attention until May of 1990, when Foundation for Global Sustainability (FGS) obtained and released to the media, documents detailing mercury and radioactive contamination at Watts Bar. Mercury damages the human brain, nervous system and kidneys.
Silt along the Pigeon River and Waterville Reservoir in Haywood County, NC, is con-taminated with dioxin, a byproduct of a chlorine bleaching process long used by Champion International Paper Corporation. The Pigeon runs along the northern border of the Great Smoky Mountains into the French Broad and the Tennessee River at Knoxville. Under pressure by environmental groups such as the Dead Pigeon River Council, Champion has recently changed its process, claiming its water emissions are dioxin-free. However, the process still discolors the river.
Stagnant or slow running water, particularly if warmed by unshaded sunlight, absorbs less oxygen and is less able to support animal life than fast-running water. Moreover, the excessive influx of organic matter in the form of sewage, fertilizers, yard waste, and agricultural runoff also reduces dissolved oxygen. Bacteria, protozoa and fungi that decompose these nutrients draw oxygen from the water, sometimes generating toxic materials as wastes. Algae further deprive the water from oxygen (see above).
Dams also deprive the water from oxygen by making the water slow, maintaining a pool of deep water far below surface-mixing processes, and piling the water up under great pressure. During warm summer months only the unnaturally cooler bottom layer, which contains relatively little oxygen, is being released by TVA's reservoirs. TVA has recently introduced technology to address the problem of dissolved oxygen and inadequate water flow. This technology generally can only improve the tailwaters.
Heating of a lake, or "thermal pollution," can harm it just as much as silt or toxic chemicals. TVA's power plants, both coal and nuclear, are located on rivers, which they use as sources of cooling water. After running through the plant's cooling sys-tem, the heated water is discharged back into the river. Specially-constructed cooling towers do not adequately reduce the heat for the local environment, and may be frozen and bypassed altogether in the winter.
Sudden rises in water temperatures, due to rainwater runoff from urban streets, parking lots and roofs, are another source of thermal pollution. Thermal pollution of creeks is increased by the elimination of shade trees and other vegetation along their banks.
Surface Water Pollution
Much of the pollution that persists in the sediments of rivers and streams is the heritage of past industrial abuse. Though industries pollute less than in the 1970's, many still release hundreds of tons of toxic materials into the waterđ-with or without the blessing of regulatory agencies.
The bioregion's largest industrial source of water pollution comes from Tennesee Eastman Kodak in Kingsport, Tennessee (440,296 pounds of toxic chemicals in 1994), followed by Champion International Paper Corporation, Canton, NC, (283,743 pounds) and North American Rayon Corporation, Elizabethton, TN (130,350 pounds). These are figures reported by the industries themselves. There is no independent check on their validity.
TVA's coal power plants also contribute substantially to water pollution by emitting toxic metals, though figures are not available (TVA as a federal agency has been exempted from federal government reporting requirements).
The bioregion's most widespread pollutant is fecal bacteria from sewage. This is is most severe in urban areas (Knoxville, Chattanooga) and overdeveloped rural areas (Blount and Sevier Counties). For most many such streams an "avoid body contact" advi-sory notification is issued by the Tennessee Department of Environment and Conservation.
Agriculture is another major contributor to surface water pollution, through nitrate, pesticide and herbicide runoff. This contamination is very diffuse, since agriculture occupies 47% of the land (compared to 2% for urban and industrial areas).
Of the bioregion's four mainstream reservoirs, Fort Loudon is the dirtiest. The bioregion's healthiest reservoir, according to TVA, is Blue Ridge in Georgia. Its sediments, too, have been toxic in the past, but no recent samples have been taken.
The wakes of powerboats erode the river's banks. Powerboats also shatter the silence of the river and spread petroleum slicks across the water. Often poorly driven, they are a danger to swimmers and to each other. Many boaters toss their trash overboard, including sewage. Many vessels are oversized and overpowered for the Tennessee.
Damming the Tennessee made commercial navigation possible. Barges are an environmentally efficient way to transport large amounts of goods and materials if dams and locks are already in place . Unfortunately, increasing portions of our Southern Appalachian forests are now headed for Mobile Bay and Japan in the form of wood chips. Also, barge terminals bring dangerous industrial operations close to the water (as a tank rupture in the early 1990's pouring many tons of tar into the Tennessee River exemplifies).
Wetlands, or swamps, are natural water filters. Because the water is shallow, diffuse, and relatively slow moving, it provides time for lush aquatic vegetation to absorb nutrients, toxic metals, and other contaminants. Wetlands also serve as a retention area during heavy rain, as well as crucial habitat for birds, fish, reptiles, insects, and amphibians.
The function of wetlands has long been misunderstood. Farmers in the Tennessee Valley found them to be a source of pesky mosquitoes and fertile farming soil when drained. For this reason, Tennessee has lost about 60% of its original wetland area.
Although agriculture has diminished in Southern Appalachia, more and more wetlands are now being lost to development. An example of this is the road extension of Parkside Boulevard through the middle of Turkey Creek Wetland in Knoxville, filling portions of the wetland for commercial development. The proposal includes a conservation easement, creating some additional new wetlands in return. Evidence shows, however, that artificially flooded wetlands do not recreate the biological or hydrological functions of the original wetland, (not even mentioning the increase in road traffic, trash, runoff and road slurry in the system).
Much of Tennessee has karst limestone cave topography and much faulted, fractured, and folded bedrock as well as sinkholes, underground watersystems, rivers or even lakes. This allows for rapid, voluminous, and largely unpredictable movement of groundwater. Caves can rapidly fill with water during summerstorms. This water is not filtered or purified as it would be if it seeped through many layers of loam, clay, or sand.
Sinkholes play an important role in drainage. Development disrupts these natural storm sewers or causes caves to collapse. This may produce flooding in areas not previously flood-prone.
Not all areas have karst topography. In areas where clay soils prevail the groundwater movement is slow. Hilly terrain means there are no large continuous aquifers. Groundwater contamination therefore tends to be localized.
About 39% of the population in Tennessee depends on ground water as a source of drinking water. Sources of groundwater contamination include: wastewater ponds from mines and industry; industrial and hazardous waste sites; leaking landfills; leaking underground storage tanks; agricultural herbicides, pesticides and fertilizers; suburban lawn-care products; underground injection of wastes and failing sewer and septic tanks. Most common sources are petrochemicals (gasoline, diesel fuel, fuel oil and motor oil), fecal bacteria (leaking sceptic tanks), and nitrates from fertilizers and sewage.
Water from private wells is often contaminated by lead from pipes. About 90% of these wells have pumps made before 1995 that contain lead alloy parts. Much of the groundwater is soft and acidic, making it corrosive enough to leach lead from the pumps.
╩The bioregion's most contaminated groundwater underlies the Department of Energy's Oak Ridge Reservation. Nuclear waste burial grounds, liquid wastes, leaking underground storage tanks, etc., have produced complex and extensive groundwater contamination by toxic and radioactive pollutants. Between 1951 and 1984 four sewage pits (S-3 ponds) were used by the Y-12 Nuclear Weapons plant to dispose 27 million gallons of various liquid wastes, including uranium and other heavy metals. Likewise, the K-25 gaseous diffusion plant has numerous burial grounds at the site. Most of the contamination appears to still be confined to the watershed in which it originated; however, the contamination is migrating, and there is no known way to eliminate it.
Despite the enormous scope and variety of groundwater contamination, water from most wells is still safe to drink. Regular testing, however is advised.
Municipal Water Supplies
Modern water treatment facilities do remove most pollutants effectively. Pollutants can, however, enter the water after treatment. It should be noted that chlorine used at the water treatment plant is itself a pollutant that reacts to form carcinogenic by-products, especially chloroform. There is evidence that drinking chlorinated water slightly increases the risk of gastrointestinal cancer. Although without it, we run the risk of infectious diseases, the necessity for chlorine treatment arises largely from the humanly caused degradation of the environment.