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Show (4) Extent of sites favorable to mosquito breed- ing before and after project construction. The following sources of disease-carrying mos- quitoes should receive prime consideration. (1) Reservoirs or impoundments. a. Extensive shallow areas in or near reser- voirs which are, or will be, covered by vegeta- tion and which will remain wet throughout the summer season. b. The occurrence of watered areas covered by floatage. This invariably results where proper clearing activities have not been under- taken, or where drift occurs. (2) Canal systems. a. Shallow water bodies resulting from in- terference with natural drainage. b. The creation of shallow undrained sumps or borrow-pits. c. The creation of water bodies by seepage from canals, or canal overflow or breaks. d. Shallow ponds or pools in canals or natu- ral channels and ditches used as waste ways or for ground water replenishment. e. Lack of excess or waste water return ditches. /. Inadequate maintenance of canals and ditches, with irregular cross sections, vegetative growth and obstructions, resulting in shallow pools and sluggish flows. (3) Water utilization. a. The creation of shallow water areas on fields improperly prepared for irrigation. b. The creation of ponds by overflow, leak- age or seepage from undersized or improperly maintained distribution canals, laterals, and ditches. c. The flooding of road borrow-pits or road ditches by irrigation water. These situations usually result where drainage has not been pro- vided or has been blocked. d. The creation of ponds by the uncontrolled flooding of waste land. e. The creation of ponds on pastures unpre- pared for irrigation or lacking provision for the drainage of surplus surface water. /. Creation of water areas due to the absence or inadequacy of subsurface ground water drainage. An agreement for necessary measures in the area exists between the Public Health Service and the Bureau of Reclamation, but is ineffective because of lack of funds. There exists also an agreement with the Corps of Engineers relating to malaria control, 262 which could be readily expanded to the broader field of insect-borne disease. Conclusions (1) Encephalitis, a disease of some concern in the Missouri Basin, may be closely associated with species of mosquitoes which bareed in pooled water. Studies have shown the relations between the in- cidence of the human disease and high densities of these disease-carrying mosquitoes. (2) Unless precautionary measures are taken, impoundments and irrigation will create situations favorable to these mosquitoes. This will be of con- cern to those within flight range, about 3 miles, and those who use reservoirs for recreation. This matter should receive consideration in locating recreation facilities. (3) In irrigated areas, mosquito control meas- ures will usually aid in conservation and efficient use of water. Adequate knowledge is at hand to control mosquito breeding in impoundments, provided the problem is properly considered in advance of con- struction. (4) Health agencies understand the conditions which spread mosquito-borne disease. This infor- mation should be furnished to and used by the con- struction agencies from the earliest planning phases of the project. (5) Mosquito control requires site preparation, shore line improvement, water level management, such artificial measures as larviciding, adult mos- quito eradication through residual spraying, and population removal from infested areas. Some- times a combination of these measures will be re- quired. The agency responsible for construction and operation of a structure should be responsible for eliminating mosquito hazards. Effective prose- cution of a control program will largely depend upon close liaison between health and construction agencies. Legislation similar to the Water Con- servation Act is needed to insure cooperation be- tween the construction and public health agencies. 4. Industrial Development in Relation to the Economy and the Water Resources Program The Problem The bearing of industrial development on the economy of the Missouri Basin area and significance to the water resources program. The Situation Instability of the economy.-The basin has been, and is, a dominantly rural area. The relative de- |