|
<br />Table 4. Estimated water use in the Upper Colorado River Basin study unit, 1990 (D,W. Litke, U,S, Geological Survey,
<br />written commun.. 1995)
<br />
<br />IMgaJ/d.l'l'tillion gallons per day; -'-, negligibleJ
<br />
<br />Ground-water use
<br />
<br />Water use
<br />
<br />Surtace-water use
<br />
<br />Consumptive
<br />use
<br />(MgaUd)
<br />
<br /> MgaUd Percent Mgal/d
<br /> Orrstre8m water lIseS
<br />Commercial 5,1 I~ 0.4
<br />D~meSli< (self, public) 2,6 9 34,2
<br />lndusrrial l.3 5 0,5
<br />Irrigation 12.4 47 3,394
<br />Power 0 0 &,6
<br />Livestock 1.0 4 61.4
<br />Mining 4,) 16 0,02
<br />Tolaloffstream 26.7 3,500
<br /> Insfrtam water uses
<br />Hydroelectric power 3,132
<br />Reservoir evaporation 110
<br />
<br />Percent
<br />
<br />97
<br />
<br />1.5
<br />11.1
<br />J.2
<br />75R
<br />O.OR
<br />3.7
<br />1.1
<br />
<br />2
<br />
<br />777
<br />
<br />o
<br />110
<br />
<br />predominantly is accounted for by irrigation in the
<br />ba~in, The remaining water-use categories account for
<br />less than 2 percent of the consumptive use,
<br />Besides ofT stream water uses, there are instream
<br />water uses that are dependent on the amount of water
<br />flowing into a stream or the amount of water stored in
<br />a reservoir (table 4), The main instream use is for
<br />hydroelectric power generation, which accounts for
<br />about 3, 132 Mgal/d of water, Reservoir evaporation
<br />accuunl~ fur about 110 Mgalld of water,
<br />
<br />Hydrologic Characteristics
<br />
<br />The hydrologic charncteristics of the basin can
<br />be represented by a generalized water budget (table 5),
<br />The budget listed in table 5 was estimated using 1993
<br />data on water supply, distribution, and use in the study
<br />unit. This generalized budget can pruvide an under-
<br />standing of the hydrolugic system and the volume of
<br />water in the basin, The estimatcd average annual water
<br />input to the basin is about 20,980,000 acre-ft/yr, The
<br />source for water input in the area is precipitation
<br />(average precipitation is 22,1 in, distributed across the
<br />basin's 17,800 mi2), Because the Upper Coloradu
<br />River Basin is a headwaters system, nu surface-water
<br />inflow occurs; the remaining water inputs by interba~in
<br />water tr3n:;fers and ground-water inflow are negligible,
<br />Water outputs from the basin are more diverse, but the
<br />
<br />predominant output is frum evapotranspiration from
<br />nonirrigated land, which accounts for about 70 percent
<br />of the total water output. The other majur uutputs fur
<br />the basin are surface-water outflow at abuut21 percent
<br />of the total basin outpUt cunsumptive water use
<br />(primarily evapotranspiration from irrigated lands) at
<br />about 4 percent, interbasin water transfers at about
<br />3 percent. and reservoir evaporatiun at about I percent.
<br />
<br />Surface Water
<br />
<br />Streamflow has been measured at about 400 gag-
<br />ing statiuns in the study unit, and in 1993, 113 of these
<br />stations were active, The first gaging statiun in the area
<br />was established in 1894 on the Gunnison River near
<br />Grand Junction; however, a station on thc Gunnisun
<br />River below Gunnison Tunnel has operated cuntinu-
<br />ously since October 1903, This station has the longest
<br />record of uperation in the study unit. Must activc
<br />stations are located in the headwaters area uf the moun-
<br />tains, Flow data are more scarce for the luw-altitude
<br />areas,
<br />Upper Culorado River Basin streams are cla~si-
<br />fied in this report into three generalrypcs: high-altitude
<br />streams, low-altitude streams. and mixed-type streams,
<br />High-altitude streams are at altitudes above 7,500 ft
<br />at'\d receive 20 in. Oi more uf precipitation annually~
<br />mostly in the fonn of snow, The basins for high-
<br />altitude streams have steep slopes and thin soils, which
<br />
<br />18 Envlronmenlal SetUng and Impllcallona on Waler Quality, Upper Colorado River Basin, Colorado and Utah
<br />
|