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<br />001532
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<br />ASA 1005
<br />
<br />This ASA comprises the largest land area of the ASA's in the Missouri
<br />region and includes four large reservoirs on the main stem of the Missouri
<br />River. Inflow into this ASA from upstream ASA's is about 13.2 million
<br />acre-feet and outflow is about 15.9 million acre-feet. Water use, exclusive
<br />of reservoir evaporation, is projected to increase from 703,000 acre-feet annually
<br />to 1,183,800 acre-feet by 1985 and to 1,972,100 acre-feet by 2000. The largest
<br />increases are projected to be for irrigation and for energy-related activities.
<br />In addition, as the Garrison and Oahe irrigation projects progress toward completion,
<br />exports from ASA 1005 to ASA 901 are expected to increase from zero in 1975
<br />to 410,000 acre-feet and 1,087,000 acre-feet in 1985 and 2000, respectively,
<br />and to ASA 1006 from zero in 1975 to 104,000 and 233,000 acre-feet in 1985
<br />and 2000 respectively. Evaporation losses from man-made reservoirs are
<br />estimated to be about 1,261,000 acre-feet annually. It is estimated that
<br />226,000 acre-feet of ground water is consumed annually, which is not expected
<br />to increase appreciably during the projection period.
<br />
<br />ASA 1006
<br />
<br />The average annual inflow from 1005 to 1006 is 15.9 million acre-feet
<br />and the outflow is 18.5 million acre-feet. The gaging station for this ASA
<br />is Sioux City, Iowa, located on the Missouri River a short distance downstream
<br />from the lowermost main stem dam, Gavins Point, and is the head of Missouri
<br />River navigation. Projected upstream water use indicates a decrease of about
<br />two million acre-feet by 1985 and 4.8 million acre-feet by 2000. The effect
<br />the projected depletions would have on navigation has not been analyzed, but
<br />it is obvious that depletions of average annual flows of 10 percent by 1985
<br />and 24 percent by 2000 would have serious impacts. Current water use, exclu-
<br />sive of evaporation, of 303,700 acre-feet is expected to increase 56 percent
<br />by 1985 and 159 percent by 2000. The import from the Oahe Irrigation Project,
<br />ASA 1005, of 104,000 acre-feet by 1985 and 233,000 acre-feet by 2000 will
<br />appreciably reduce the impact of the projected water use increase. The use
<br />of ground water is significant and is currently estimated to be about 350,000
<br />acre-feet annually and increasing to about 466,000 acre-feet by 1985 and to
<br />788,000 acre-feet by 2000.
<br />
<br />ASA 1007
<br />
<br />This ASA essentially covers the drainage basins of the North and
<br />South Platte Rivers in Colorado, Wyoming and Nebraska. The average annual
<br />outflow is about 1,143,600 acre-feet annually. Transbasin diversion from
<br />the Colorado currently is about 326,000 acre-feet annually and is projected
<br />to increase to 405,000 acre-feet by 1985 and 533,000 acre-feet by 2000.
<br />Ground water consumed is currently estimated to be about 618,000 acre-feet
<br />annually and is projected to increase to about 762,000 acre-feet by 2000.
<br />The total estimated water consumed, exclusive of evaporation, is about 2,659,200
<br />acre-feet annually, and is projected to increase 16 percent by 1985 and 32 percent
<br />by 2000. Considering the increased import from the Colorado River basin and
<br />assuming that the increased water use would deplete the available surface
<br />supply, the effect on the average annual outflow would be to reduce it by
<br />about 37 percent or to about 919,000 acre-feet annually.
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<br />11-132
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