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<br />....:., <br />}}.( <br /> <br />M <br />~ <br />f\j <br />~ <br /> <br />~~~.~), <br /> <br />Present Uses <br /> <br />The natural flows of the rivers and streams in the Basin are sig- <br />nificantly affected by man's present day activities. These uses, both <br />consumptive and nonconsumptive, are briefly reviewed below. <br /> <br />Depletions. As estimated by the Upper Basin States, in-basin <br />consumption and out-of-basin exports account, under present (either <br />calendar year 1975 or calendar year 1976) conditions of development, for <br />depletions averaging 3.l4 maf per year.1 To this must be added average <br />annual evaporation (for water years 1971-1975) from Colorado River <br />Storage Project reservoirs (Flaming .Gorge, Blue Mesa,. Morrow Point, and <br />Lake Powell) of .528 maf (U.S. Bureau of Reclamation, 1977a, p. 23). <br />Thus, total average annual depletions amount to 3.67 maf, or nearly 25 <br />percent of the estimated average annual natural flow (1906-1974) of the <br />Colorado River at Lees Ferry. <br /> <br />In table 3.2, these depletions are disaggregated by WAU and func- <br />tion2 (see appendix B for depletions on a State-by-State basis). Nearly <br />70 percent of the average annual depletions (exclusive of evaporation <br />from Colorado River Storage Project reservoirs) is attributable to agri- <br />culture in the Upper Basin. Slightly less than 25 percent is attributed <br />to exports out of the Upper Basin, while the balance is distributed among <br />the remaining uses. <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 for the water years <br />1971-1975 (U.S. .Bureau of Reclamation, 1977a, pp. 32-36). <br /> <br />2. The functions are defined as follows: <br />a. Municipal and Industrial (M&I): water consumed by domestic, <br />rural domestic, commercial, retail, and manufacturing facilities. <br />Final processing of raw material for other products is also in- <br />cluded (e.g., petroleum for synthetic fibers). <br />b. Agriculture: <br />(1) Irrigation: water consumed in growing crops 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, Wildlife, and Recreation: water used for maintenance of <br />fish, wildlife, and recreation areas which is not returned to <br />a stream. Also included is water consumed in the irrigation of <br />crops for fish and wildlife feeding. <br />f. Minerals: water consumed in the extraction, processing, and <br />shipment of raw minerals. <br /> <br />3-7 <br />