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8-6 I I I I I I I I I I I I I I I I I I I flows are projected to decline by some 3.2 million acre-feet by 1985 and by another 3.7 million by the year 2000. Most of the streams within the subbasin are comparatively small, and seasonal water shortages are common. Because the streams drain primarily agricultural areas, runoff causes high concentrations of nitrates, phosphates, and insecticides. Normally, concentrations of inorganic salts are low. Most streams carry heavy loads of suspended sediment. Turbidity is high most of the time. All have exper1enced' undesirably low levels of dissolved oxygen due to inadequately treated waste waters, low flows, and warm water temperatures. Low dissolved oxygen levels also occur after heavy runoff because of high turbidity, The states of the Middle Missouri Subbasin govern the use of water through several different legal systems. Minnesota and Missouri recognize the riparian doctrine. Kansas and Nebraska depend upon prior appropriation systems but acknowledge riparian doctrine in varying degrees. Iowa makes substantially all uses of water subject to permit and administrative regulations governing diversion, storage, and withdrawal over a period of time not exceeding 10 years. PROBLEMS AND OPPORTUNITIES Nonpoint source pollution is the major water resources problem in the Middle Missouri Subbasin. Other major problems include flooding along many of the tributary streams, consumptive use and diversion by upstream States which decreases the amount of water available for downstream use, drinking water of poor or unacceptable quality, oxbow lake elimination and channel straightening, and demand for water access and recreational facilities. steep slopes and soil types in Iowa and northwest Missouri cause severe gully erosion. Streambank erosion is a principal problem in the Nemaha Basin in Nebraska, and in the Nishnabotna and Nodaway Basins in Iowa. Nebraska