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<br /> <br />Overland runoff contributes large amounts of silt and <br />organic material to streams throughout the subbasin. In reaches <br />of the Osage, Marias de Cygnes, Grand, Chari ton, and Blue Rivers, <br />dissolved oxygen levels during occasional periods of low flow <br />drop below desirable levels for propagation of aquatic life. <br /> <br />Water quality in valley fill aquifers lying along the <br />Missouri River and its tributaries appears to improve in the <br />downstream direction, probablY .because of progressively <br />increasing average annual preci9itation. <br /> <br />PROBLBIIS AND OPPOR'l'll1IITIBS <br /> <br />The principal problems in the Lower Missouri Subbasin are <br />nonpoint source pollution; potential power shortages given <br />expected future demands; and uncertain water supplies for coal <br />gasification and other potential energy development. Others of <br />lesser impact include local ground water supplies of unacceptable <br />quality in some parts of the subbasin; isolated flood problems; <br />overcrowded recreation areas; declining acreage of wetlands and <br />forests; and riparian habitat impaired by continuing development. <br />The basin is just beginning to explore the opportunities <br />available through modern irrigation practices, and coal <br />gasification is possible, given the coal deposits available in <br />some areas. <br /> <br />Nonpoint source pollution is the most serious problem in the <br />Lower Missouri Subbasin. This problem results from agricultural <br />runoff, urban storm water drainage, acid mine drainage, and <br />individual waste disposal systems. <br /> <br />In north and west central Missouri and in southern Iowa, <br />active bank erosion is common and heavy sediment loads are <br />consequently carried by many Missouri River tributaries. Steep <br />slopes and soil types cause upland soil erosion, especially in . <br />northwestern Missouri and southwestern Iowa. The productive <br />cropland soils in the South Grand, Blackwater, Grand, and <br />Chariton Basins are primarily of loess or loess over glacial till <br />and are often tilled. <br /> <br />Due to the rolling topography, annual soil loss on <br />unprotected tilled cropland often exceeds 25 tons per acre. This <br />loss is five times the rate of loss allowable to maintain <br />sustained crop production and also is a major contribution to <br /> <br />-230- <br />