Water loss by evaporation due to the heat effluent depends on many factors. In this geographic area, humidity conditions are such that excessive evaporation should not occur. The maximum rate of evaporation for a total of three reactor units operating on a hot, dry day would be about 5% of the natural flow of water to the lake. Under normal conditions it would be considerably less than this. Use of lake water by municipalities also will cause a relatively small removal of water. The predicted concentrations of chemicals in water released to Hartwell Reservoir are given in Table III-6. The concentrations of these chemicals should be determined from studies at operating conditions and reported. This program should include at least the following field measurements: (1) Identification and quantities of chemicals discharged. The (2) The acidity (pH) should be measured at the point of discharge. 2. Air Use The only use of the air will be for dilution of gases from operation of the nuclear plant and for a small boiler fired with fuel oil. This boiler is for occasional use only. Some localized increase in fog may result from the increased surface temperature of the reservoirs. This should affect areas near the reservoirs, but not affect areas a few miles away. Additional ecological studies are necessary to supply data for a more comprehensive analysis of biological impacts caused by actual plant operations. The applicant states that the temperature and dissolved oxygen of the intake and discharge waters will be monitored and a program instituted to study productivity in the lake at (2) strategic sites (not specified) by measuring biomass accumulations. Harold W. Brown, Columbia University, and Charles M. Weiss, University of North Carolina, are listed as consultants. Dr. Weiss contributed a section on periphyton measurements to the Lake Norman studies. The applicant has a program aimed at controlling breeding grounds of a variety of mosquitoes (Anopheles punctipennis, Culex nigripalpus, Culex pipiens, Culex restuans, and Culex salinarius). Presently the breeding areas are sprayed with a mixture of No. 2 diesel fuel and transformer oil (15 to 20 gallons per surface acre). Close inspection of sprayed areas by members of the South Carolina State Board of Health have not revealed any discernible effects on water fowl or aquatic mammals in the area. plans regarding the mosquito program are to stock known breeding areas with Gambusia affinis, the mosquito fish, in order to increase the biological control of mosquitoes. No cases of malaria in the area have been reported since 1949. The attempt at biological control of mosquitoes with Gambusia is a worthy effort. Future Alteration of 26,000 acres from a terrestrial to an aquatic ecosystem has been the major biological impact in the Keowee-Toxaway area. The main environmental impacts on most of the remaining terrestrial ecosystems can be expected to result from: (1) operations of the applicant's subsidiary, Crescent Land and Timber Corporation; (2) game management practices of the South Carolina Wildlife Resources Department; (3) activities of persons constructing permanent residences or visiting the area; and (4) management of transmission line systems. The usual environmental effects produced by timbering organizations such as the Crescent Land and Timber Corporation are: (1) cultivation of tree species preferred for pulpwood or saw timber, (2) removal of tree species undesirable for their purpose, (3) alteration of species compositions and/or population dynamics of understory vegetation and animals, (4) construction of access roads, (5) formation of logging roads, and (6) construction of fire-protection areas. Land and timber practices of organizations which own an area are generally better than practices of those who only buy and remove the timber. Certain wildlife management practices of the South Carolina Wildlife Resources Department can be expected to cause environmental effects in areas they manage. For example, management of "preferred" species such as deer, bear, boar, and turkey usually increases the densities of these populations. Management of the white-tailed deer apparently will be emphasized. If populations of this large mammal become dense, then considerable impact on preferred, accessible foods of this deer will be manifested, as well as some trampling effects. Similarly, management of areas by selective cutting or planting of food or cover vegetation for wildlife can have local effects on plant and animal populations. Effects of hunters on an area are of economic and academic importance mainly, since the areas are managed to attract hunters. Stocking of deer in the wildlife area as a part of a statewide program may baye resulted in the occurrence of Rocky Mountain spotted fever in the area. The Coon Branch Natural Area and the understory vegetation of the "virgin forest" may be vulnerable to high populations of large game animals because of browsing, grazing, rooting, and trampling. If such populations are attracted to the area, thought should be given to building an exclusion fence if the objective is to preserve a truly virginal forest. Residential subdivision development, road construction, and similar activities of man will subtract from forests and other natural areas in the region. The usual effects are clearing of the vegetation of an area, construction (roads, buildings, picnic tables, rest rooms), trampling, noise, and pollution. An increase in road kills of animals can be expected when vehicular traffic increases. Wastes resulting from human activities (sewage, chemicals, garbage, and litter) will create problems unless handled properly. The applicant is a leader in good management of land under power transmission lines. For example, the contouring of soil and planting of low vegetation, such as fescue and lespedeza, under transmission lines from the Keowee-Toxaway area are serving to stabilize the soil and reduce erosion on these recently disturbed areas. In essence, ecological effects of transmission lines in this project have been to change 3900 acres of forest to a habitat type regulated by the applicant or to an acceptable type desired by the landowner. Consequently, some species of plants and animals will benefit from these habitat changes and others will be eliminated or reduced in numbers. In general, many mobile species benefit from the presence of ecotones (transition zones between diverse communities) between power-line areas and surrounding forests and fields, if suitable food and cover are provided under the power lines. The local terrestrial environmental impact of the Station operation will be relatively minor. Some effects such as fog and slight temperature rises from heat dissipation in the lake will undoubtedly be evident on land areas near the discharge of reactor condenser water. 3. Aquatic Impacts The location and design of Station in relation to Keowee Lake suggest that the major effects on aquatic life in Lake Keowee will result from (1) discharge of thermal effluents from the power plant condensers and (2) entrainment in cooling water circulating through the plant. Organisms in the headwaters of Hartwell Reservoir will be subjected to slight increases in temperatures as the hydroelectric plant operates, drawing in some of the discharge plume from the nuclear plant. The intake structure of the hydroelectric plant is designed to withdraw Lake Keowee water from the surface down to the top of the intake structure (approximately 35 ft below lake surface). This thermal discharge probably will favor, at least in the headwaters of Hartwell Reservoir, organisms which can tolerate periodic surges of warmed water. These surges will result in changes in level which may amount to 11 feet at times (Section III.C.2). No evaluation of the impact of this surge has been made but it is likely the specialized community of organisms will develop. A detailed evaluation of possible effects on the aquatic biota is not possible at this time since the information available relates to preliminary fish surveys conducted in late August of 1969 (see Appendix G of the Applicant's Report). Information on littoral, benthic, and planktonic organisms is not available at this time for Lake Keowee and Hartwell Reservoir. Hence, the following comments are of a general nature and should be considered as a preliminary review of possible problem areas. Biological effects of a given temperature or temperature pattern may be different in different populations, at different ages, and in different life cycle stages, and such effects may depend on the temperature history of the individuals tested as well as effects of other environmental factors. Organisms usually experience daily or seasonal temperature fluctuations in their natural habitat, and these changes can be important prerequisites for completion of their life cycles. The temperature range tolerated by many species of organisms may be relatively narrow during early developmental stages (eggs and larvae), widening somewhat as fingerlings, and finally narrowing again in adults. Often the tolerance range is more restricted during the reproductive phase than during other phases. Many of the more mobile organisms such as fish, some zooplankton, and bottom associated animals may avoid lethal temperatures by vertical and/or horizontal migration into a more suitable environment. a. Bottom Organisms and Insects River-bottom plants and animals decreased in number when the water temperature exceeded 30°C (86°F) in a study on the effect of warm water discharge to a river. A 35°C (95°F) water temperature was found to (4) cause a detrimental effect on macroinvertebrate fauna of the Delaware River, especially the caddis fly, any of which were killed, while those surviving were extremely sluggish. Studies on the shift of the composition of macroinvertebrate populations showed that no immediate kills resulted from a temperature rise of 14°C (25°F). However, persistent exposure at 35°C (959) over a 24-hour period caused a shift in the population composition. In a study of the York River, in Virginia, benthic invertebrate populations were affected by thermal (8) discharges, especially during the months of normally high temperatures. The tolerance limit for a wide variety of adult organisms in the structure of benthos appears to be close to 32°C (90°F), with extensive losses in numbers and diversity of organisms accompanying further temperature increases. The heated effluent may alter the benthic communities in the immediate area of the discharge, but effects in the rest of Lake Keowee will probably be undetectable since the heated plume will rise to the surface or remain at an intermediate level. The meroplankton stages (free-swimming larval stages of sessile forms) may offer considerable evidence of the thermal vulnerability of important forms. If heated waters are dispersed as a thin layer over cooler water, the diurnal migrations of zooplankters may also be influenced. Many microcrustaceans swim to the surface to feed at night and descend to cooler waters during the day. These animals may encounter a hot layer at the surface, and the response of such migrating species is unknown. It should be noted that acclimation is of considerable significance to insects in their natural habitats. Times during which there is great est danger of exposure to high temperatures are usually preceeded by periods during which temperatures rise gradually. When lethal temperatures are approached, insects may already be acclimated to them. The specific time of day when maximum temperatures are encountered in nature is also usually preceded by several hours of gradual warmi ng, allowing physiological acclimation to occur. The continued effects of these processes may raise the mortality threshold by a degree or more. F(9) Invertebrates usually reproduce within a more narrow range of temperature than they can tolerate as adults. Animals in areas where the water is affected by heated effluents may, therefore, be prevented from reproducing. Normal development of Aedes larvae does not occur after exposures at 42 to 44°C (108 to 111°F). Sublethal temperature exposures seemingly destroy the internal developmental mechanism, and exposure to high temperatures may delay development, resulting in a later emergence. (10) |