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Show sified by the system's multiple-purpose character, requiring flexibility in water level management. No similar system had previously been developed in this country from which to draw experience. At the outset, State health departments urged TVA to conform to State and local regulations which required private owners and operators of reservoirs in areas favorable to propagation of Anopheles mosquitoes to apply malaria control measures. TVA agreed, and has planned its ma- laria control program in cooperation with repre- sentatives of State health departments. It was rec- ognized from the inception of the reservoir program that failure to adopt such measures would nullify the benefits to the region for which the dams and reservoirs were being constructed. The major control measure is water level man- agement. This controls the plant growth along the reservoir margins and also destroys the larvae of the malaria-bearing mosquitoes. At the end of fiscal year L949 permanent malaria control meas- ures had been carried out on 8,500 acres, nearly half of the 19,500 acres proposed for such measures. Such permanent measures include dikes to separate shallow areas from the main body of the lakes, drainage ditches and pumps for use during the breeding seasons, and alteration of shorelines by deepening and filling to eliminate shallow flats and create regular and steep shorelines. Clearing tlie shorelines of vegetation and control- ing plant growth along the water's edge greatly re- duced the mosquito menace. Application of larvi- cides from airplanes is among the effective devices employed. At first this larvicide was powdered paris green, <lusted by plane along the edges of the reservoirs in the early morning hours. DDT has since been adopted as the chief larvicide. Experi- mentation is proceeding in the use of other aerosols and sprays. The TVA has four malaria control airplanes, and experiments have also been con- ducted with helicopters. These measures have been effective. Blood sur- veys in critical reservoir areas in 1949 and 1950 disclosed no malaria parasites, as compared to the high incidence in 1933. Stream Sanitation The increase in municipal and industrial waste load resulting from valley development has not been met witih parallel progress in waste treatment. Wastes from 201 centers of population, including municipalities, discharge into the streams both domestic and industrial wastes. In addition 148 industries discharge wastes directly to the streams. The organic waste load from 185 municipalities and 87 industrial outfalls is equivalent to the wastes from a population of 2,482,000. Sixteen other munici- palities and 15 industries are discharging organic wastes, the population equivalent of which is un- determined. In addition, 18 of the above indus- trial plants and 43 other industries discharge in- organic pollution to the streams. The major in- dustrial contributors of organic wastes are the pulp and paper, chemical, and textile industries. In- organic wastes include acid wastes from coal mines, toxic metal wastes from metal processing plants, phenolic and other taste- and odor-producing wastes from coke and chemical plants, brines and sulfates from chemical plants, sediment from mining opera- tion and soil erosion, and color producing sub- stances from textile and paper and pulp industries. The major pollution load originates in the upper portion of the basin above Chattanooga. On the main stem of the Tennessee River the largest con- centrations of both domestic and industrial pollu- tion are found around Chattanooga and Knoxville, Tenn. Nearly 90 percent of the total pollution load in the basin is discharged into the Holston, French Broad, and Clinch Rivers and into the main stem of the Tennessee River. The Little Tennessee, Hiwassee, Elk, and Duck Rivers receive about 10 percent of the pollution. The discharge of domestic sewage has resulted in enough bacterial pollution below a few large pollution centers to make many miles of streams unfit for domestic use or recreation. On the North Fork of the Holston River, chemical plant wastes discharge excessive amounts of hardness, chlorides, and sulfates. Hardness values of the stream aver- age over 600 parts per million with maximum values in excess of 2,500 parts per million. Water quality is impaired as far as Knoxville, at the mouth of the Holston. Color-producing substances dis- charged to the French Broad and Pigeon Rivers also impair water quality. Sediment from mining and ore processing opera- tions, discharged to the Nolichucky River, a major tributary of the French Broad, has reportedly dam- aged fish life. Pulp and paper mill wastes empty- ing into the upper reaches of the French Broad, Pigeon, and Tuckasegee Rivers add oxygen-deplet- ing substances and color to these streams, the ef- 730 |