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Show 9.2 million kilowatts of potential hydroelectric ca- pacity in "the basin, accomplished in step with other functions of multiple-purpose water resources de- velopmen-t, in accordance with power needs, and in a manner consistent with the most beneficial combined development of resources for all purposes. Domestic and Industrial Water Supply Roughly 1,300 cities, towns, and villages of over 250 inhabitants have public water supplies. Of these about 1,100 are from ground water sources. The number of people served is estimated at 3.8 million. Some communities, notably Denver, Sioux Falls, and Rapid City, are experiencing difficulty in obtaining; adequate water of proper quality. As population grows, the water supply problem tends to become more acute both as to quantity and qual- ity. Local interests will generally be able to finance water supply and treatment for municipal and in- dustrial needs, except where the sources are polluted. However, multiple-purpose develop- ments cajn improve water supplies in some areas greatly. Full water resources development will require assistance in controlling erosion to reduce sediment, abating pollution, and replenishing underground aquifers. Conservation storage in multiple-pur- pose reservoirs will be used as a source of water supply. In all cases of competition for use of a limited water supply, the program must recog- nize the priority of domestic requirements. Navigation and Bank Stabilization Full development of navigation potentialities de- pends primarily on main stem improvements. The existing 9-foot channel project up to Sioux City, should it be found economically feasible, might be extended to Yankton as an artery for water-borne commerce. Through its interconnection with the inland waterway system on the Mississippi River and major tributaries, it might provide water trans- portation for bulk commodities between the basin and all major river ports on the system and the deep water ports on the Great Lakes and the Gulf of Mexico. Channel extensions on tributary streams, harbor improvements, and terminals for transship- ment between rail and water carriers should be provided to obtain the most efficient use of all trans- portation facilities. Harbors and terminals should be installed as needed in the major reservoirs for recreational and other craft. In connection with the lower river navigation project, the present system of bank stabilization works should be completed in all critical locations to preserve the navigable channel and prevent de- struction of farm lands by undermining of banks and loss of improvements adjacent to the channel. Main stem navigation can be maintained most economically by open channel improvements, com- bined with multiple-purpose reservoir releases to supplement uncontrolled flows, return flows from upstream uses, and releases for pollution control. Should upstream depletions curtail the water sup- ply needed for open river navigation and should further navigation improvement be economically warranted, locks and dams could be provided for slack-water navigation. Approximately 750 feet of available head between Yankton and the mouth of the river offer potential hydroelectric power. Pollution Abatement Full water resources development will require prosecution of pollution abatement measures to cor- rect or prevent impairment of water quality. Stream regulation will, in some instances, aid in pollution abatement, but industries or municipalities should not be allowed to discharge untreated waste merely because a reservoir is established to augment low flows. The ultimate objective is twofold: first, to provide abatement measures to facilitate maxi- mum use of water resources; and, second, through low flow augmentation and related measures to obtain maximum improvement in stream environ- ment. In general, a minimum of primary treat- ment will be necessary for all wastes, with additional treatment required as conditions of stream flow and use demand it. Mosquito Control The construction of reservoirs and irrigation works may increase the nuisance of mosquitoes, and the hazard of insect-borne disease. Antimosquito measures should, therefore, be included as part of a basin program. Drainage In many local areas, natural drainage is inade- quate because of flat slopes, tight soils, or water- logging by waters from up-slope irrigation. A com- 275 |
