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Show power has been marketed predominantly through private utilities. Because of the close relationship between the nature and distribution of the markets and the character, location, and scheduling of power units at dams to be constructed, integration of the Fed- eral and non-Federal power activities to the maxi- mum practicable degree is essential. And because of this same close relationship, the extent and nature of participation of the power-marketing agency in Federal planning and scheduling power installa- tions should be clearly defined in order to assure the most economical and effective application of congressional power-marketing policies. 7. Insect-Borne Diseases The Problem Need for mosquito control in basin-wide programs. The Situation Malaria is the principal insect-borne disease as- sociated with water resources use in the Ohio River Basin. In most of the area the disease is a poten- tial problem rather than an active one. Climatic conditions are more favorable for development of the disease in the southern part but an outbreak can occur in any part of the basin. For example, an epidemic of malaria occurred at Terra Haute, Ind., in 1938, 1939, and 1940, and resulted in 1,500 known cases. The epidemic was attributed to a man-made favorable breeding place for mosquitoes, combined with the presence of a migratory worker who had malaria. In the 1800's, malaria was ex- tensive in the upper Mississippi Valley States for 20 to 50 years. In 1910, Hales Bar Reservoir, in Tennessee, was built with no regard for mosquito- control measures and a serious malaria problem resulted. Impoundments of water for water supply, power development, flood control, navigation, and other purposes frequently increase the number and ex- tent of favorable breeding places for mosquitoes unless proper control measures are provided. It is the present practice on Federal projects to make preimpoundment and postimpoundment malaria control surveys and to provide the necessary con- trols to prevent a malaria hazard. In addition to these large artificial lakes, many small farm and fish ponds have been and are being constructed in the basin. Many of the rivers and creeks of the system are bordered by old river runs whose edges are vegetated and surfaces partially covered with aquatic plants. Climatic conditions over much of the basin favor production of mosqui- toes, including those which transmit malaria. Mosquitoes breed in quiet, shallow water where aquatic vegetation and floating debris afford pro- tection to the insect undergoing developmental stages. Such habitats are created by water projects if preventive measures are not employed. The ma- laria mosquito has been sufficiently prevalent in portions of the basin to propagate malaria. At present neither the mosquito nor the malaria prob- lem is serious, yet a heavy production of malaria mosquitoes would constitute a potential disease hazard. This is particularly important in view of present-day world travel and the prevalence of ma- laria in other parts of the world. The Public Health Service provides consultant service and prepares malaria survey reports for river development projects of the Corps of Engi- neers. Some States have effective laws related to malaria control governing the development of im- poundments by private interests and other agen- cies. Most of the States in this basin have no ef- fective regulations. There is no established significant relation be- tween other insect-borne diseases and water re- sources development in the basin. There is a possibility, however, that such relations will de- velop, possibly in connection with encephalitis or other insect-borne diseases. Conclusions Malaria is the only insect-borne disease of sig- nificance which has established relations with water resources developments in the Ohio River Basin. Malaria epidemics can occur anywhere in the area. At present malaria is a potential problem rather than an active one. It is important that project planning include measures for mosquito control. Experience shows that preventive measures regarding mosquito con- trol in relation to water impoundments are much more economical than corrective or remedial meas- ures. Control measures now recognized as neces- sary at projects being developed by Federal agencies should be continued and expanded, if necessary, to meet special situations that might arise in connec- tion with water resources development. 677 |