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<br />Present Uses
<br />
<br />The natural flm,s of the rivers and streams in the Upper Basin are
<br />significantly affected by man's present day activities. These uses,
<br />both consumptive and nan-consumptive, are ,briefly reviewed below.
<br />
<br />~ Depletions, As estimated by the Upper Basin states, in-basin
<br />en consumption and out-of-basin exports account, under present (1975-1976)
<br />~ conditions of development, for depletions averaging 3.14 maf per year,l
<br />~ To this must be added average annual evaporation (for water years 1971-
<br />1975) from Colorado River Storage Project reservoirs (Flaming Gorge,
<br />Blue Mesa, I~rrow Point, and Lake Powell) of .528 maf (U.S. Department
<br />of.the Interior, 1978, p. 23), Thus, total average annual depletions
<br />amount to 3,67 maf, or nearly 25 percent of the estimated average annual
<br />natural flaw (1906-1974) of the Colorado River at Lees Ferry.
<br />
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<br />In Table 3.2, these depletions are disaggregated by WAU and function
<br />(see Appendix B far depletions an a state-by-state basis). Nearly 70
<br />percent of the average annual depletions (exclusive of evaporation from
<br />Colorado River Storage Project reservoirs) is attributable to agriculture
<br />in the Upper Basin. Slightly less than 25 percent is attributed to exports
<br />out of the Upper Basin, while the balance is ,distributed among the remaining
<br />uses.
<br />
<br />It is important to understand that the depletions presented in Table
<br />3.2 represent annual averages under present conditions of development,
<br />not estimates of the depletions that actually occurred in 1975-1976.
<br />
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<br />
<br />1. By way of comparison, the U.S,.Bureau of Reclamation's'most recent
<br />estimates of average annual depletions under present conditions of devel-
<br />opment amount to 3.02 maf, These depletions were ior the water years
<br />1971-1975 (U.S. Department of the Interior, 1978, pp, 32-36).
<br />
<br />2. The functions are defined as fallows:
<br />a. Municipal and Industrial (H&I) - water consumed by domestic,
<br />rural domestic, commercial, retail, and manufacturing facilities.
<br />Final processing of raw material for ather products also included
<br />(e.g., petroleum far synthetic fibers),
<br />b. Agriculture
<br />(1) Irrigation - water consumed in growing craps and fiber,
<br />Includes ditch evaporation, loss to phreatophytes, feed
<br />for livestock, and evaporation from reservoirs,
<br />(2)'Livestock - drinking water for livestock and stockpond
<br />evaporation,
<br />c. Thermal - water consumed in steam electric power generation.
<br />d. Exports - diversions to another basin or WAU within the Upper
<br />Basin (a negative export indicates an importation of water).
<br />e. Fish, llildlife, and Recreation - water used far maintenance of
<br />fish, wildlife, and recreation areas which is not returned to a
<br />stream, Also, water consumed in the irrigation of crops for fish
<br />and wildlife feeding,
<br />f. Minerals - wntcr consumeJ in the extraction) processing and
<br />shipment of raw muteriGls.
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<br />3-7
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