|
<br />.\ ''';
<br />J.0 ;.....
<br />
<br />14. DJBCUSSION OF ULTIMATE DEPLEl'IONS.
<br />
<br />future exportation possibilities were estimated by this office at 1,864,000
<br />acre feet.
<br />
<br />The foregoing table, which does not appear in the Report, discloses that
<br />under ultimate development, - meaning when all projects under construction and
<br />authorized in the Upper Basin are completed, when all irrigable lands of
<br />existing enterprises in the Lower Basin are being irrigated, and when all
<br />potential power, irrigation, exportation and other projects listed in the
<br />Report are constructed and in operation, - the total depletions of the flow of
<br />the Colorado River above Lee Ferry will average 7,643,000 acre feet annually,
<br />and below Lee Ferry will average 11,092,600 acre feet annually, or a total in
<br />both basins of 18,735,600 acre feet annually'for the entire Colorado River
<br />Basin.
<br />
<br />Depletions are not constant year after year or by cycles of years, and,
<br />under ultimate development will not amount to 7,643,000 acre feet each year
<br />in the Upper BaSin, or to 3,821,000 acre feet each year in Colorado. :rn years
<br />and periods of above-average precipitation and runoff, the depletions will be
<br />above average. Ditches in Western Colorado will divert and apply more than
<br />average amounts of water, and depletions will be above average because of
<br />greater consumption incident to the prOduction of above average amounts of
<br />crops, and because of greater contributions to ground water storage. Export
<br />diversions, which vary with runoff, will also be above average. More than
<br />usual quantities will be stored in reservoirs, and thus will be withheld from
<br />the streams in favorable years. And because of greater volumes in storage,
<br />with accompanying increase in areas of exposed water surfaces, the evaporation
<br />losses from reservoirs will be above average in amount during years and periods
<br />of above average precipitation and runoff.
<br />
<br />According to the Report, the ultimate depletions in the Upper Basin under
<br />long-time average or normal climatic conditions, and during a minimum ten-year
<br />cycle such as 1931-1940, will be as follows:
<br />
<br />ULTIMATE AVERAGE ANNUAL DEPIETIONS
<br />UPPER COlORAlXl RIVER BASIN
<br />(Acre Feet)
<br />
<br />'DROUGHT CYCIE lONG TIME AVERAGE
<br />1931-1940 CONDITIONS NORMAL CONDITIONS
<br />
<br />CONSUMED IN BASIN
<br />
<br />3,832,000
<br />2,245,000
<br />
<br />MAIN STEM RES. lOSS
<br />TOTAL DEPLETIONS
<br />
<br />831,000
<br />6,908,000
<br />
<br />3,832,000
<br />2,771,000
<br />1,040,000
<br />7,643,000
<br />
<br />EXPORT DIVERSIONS
<br />
<br />Note that export diversions and main stem reservoir losses during a drought
<br />cycle such as 1931-1940 are estimated at approximately 80 per cent of normal.
<br />To such a relation this office agrees. On the other hand this office cannot
<br />
<br />(20)
<br />
|