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<br />24
<br />
<br />Table 2. - Land and Water Acreage for 1975, 1985 and 2000, Missouri River Basin
<br />
<br />Land Uae 1975 1985 2000
<br /> 1,000 acres
<br />Agricultural Lands
<br />Cropland
<br />Nonirrigated 89,659 91,133 91,024
<br />Irrigated 11,303 14,139 17,154
<br />Pasture and Range 167,450 162,298 158,465
<br />Forest and Woodland 26,296 26,156 26,072
<br />Other 3,698 3,689 3,697
<br />Subtotal 298,406 297,415 296,412
<br />NonagrlcufturalLands
<br />Transportation, Urban
<br />Built-up 7,435 8,149 9,099
<br />Other 18,069 18,114 17,954
<br />Subtotal 25,504 26,263 27,053
<br />Total Land Area 323,910 323,678 323,465
<br />Total Water Area 4,598 4,830 5,D43
<br />Total Area 328,508 328,508 328,508
<br />Sources: Missouri River Basin Comprehensive Framework Study Report
<br /> 1975 National Water Assessment, Missouri Region,State - Regional Future
<br />
<br />Water Resources, Development,
<br />and Utilization
<br />
<br />WATER RESOURCES
<br />
<br />The Missouri River Basin is, in general, well endowed
<br />with surface and ground water resources. However, the oc-
<br />currence and availability of water is highly variable, subjecting
<br />portions of the Basin to recurrent local and seasonal shortages.
<br />
<br />Surface Water Availability
<br />
<br />Precipitation over the Basin averages 20 inches ann~-
<br />ally, providing more than 500 million acre- feet of water. Infiltra-
<br />tion and evaporation deplete a large amount of this naturally-
<br />occurring moisture. Runoff entering the streams varies widely
<br />across the Basin, ranging annually from less than an inch in
<br />parts of the plains to more than 12 inches in the mountains and
<br />the humid southeast. This runoff would account for an average
<br />of about 65 million acre-feet of natural flow annually near the
<br />mouth of the Missouri River at Hermann, Missouri, exclusive of
<br />manmade evaporation and consumptive uses.
<br />
<br />Under 1970 conditions of development and utilization,
<br />the net average annual outflow from the Basin was estimated
<br />
<br />to be 53.6 million acre.feet.1. Recent appraisals, based upon
<br />an aggregation of Basin States' estimates of water use, indi-
<br />cate a 1975 average annual flow cf 49.4 million acre-feet at the
<br />mouth.2
<br />
<br />Abnormally low and high streamflows are not uncom-
<br />mon in most parts of the Basin. Indicative of the drought poten-
<br />tial is the fact that natural runoff as low as half the mean has
<br />occurred in nearly 10 percent of the years of record. At the
<br />other extreme, severe flooding caused by snowmelt, spring
<br />rains, and thunderstorms, is common in many drainages
<br />throughout the Basin.
<br />
<br />Surface Water Quality
<br />
<br />Overall, the water quality of the Basin's waterways can
<br />be classed as "fair." In the western portions, many of the
<br />mountain streams remain pristine and pollution-free. Sediment
<br />and naturally occurring dissolved solids concentrations are the
<br />major problems in the rivers traversing the plains. In areas
<br />where irrigation is practiced, return flows from croplands are
<br />often laden with fertilizers, pesticides, and herbicides, degrad-
<br />ing nearby watercourses. Runoff containing high concentra-
<br />tions of organic wastes from animal feedlots is another major
<br />agriculture.related water quality problem. Finally, municipal and
<br />industrial wastes continue to pollute many of the Basin's major
<br />
<br />1 Missouri Basin Inter-Agency Committee, The Missouri River Basin Comprehensive Framework Study Report, June 1989, Vol. 1 , p.
<br />58.
<br />
<br />2 1975 National Water Assessment. Technical Memorandum 2, p. 11-147.
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