WSP07419 - Laserfiche WebLink

Home Browse Search

o en ..,. . , -- PART III. HIs:-rR'i)F WATER RESOHRCE DE'tELOP!.!E:'lT 1'1. J.YTi;;ation Dr>'.feloI'mr>n~ Irrl~ation levelopmcnt in the Upper Ba~ir. took pl~ce gradually from thf> be,>; nni:1.:- 0 f settlement 'lCOL:t lr:f;O Lu: '..'R5 hasten'?i bj' -the purchase nr 1~~1 ~ro~ ~he Indians in 1873. About 800.000 acres ~~r~ lrrif,ated by 190~. Bet~eer. 1~05 and 1~20 thp Jevelopment of irri~~iei land continued a~ 3 rapi1 p~ce. and by 1920 nearly 1,400.000 ~cres were irrig~ted. The ie.elon~ent then levelerl of~ and Incre~se since ~hat time hqs been slow. In 19f5, 1,600,000 aCTf"S ...-ere unrler irripation in the Upper Basin. Since l~~, ~here has been verJ little chan~e. The slo.... (TO'.,t.h in irrilSated acre8E"~ in the Upper Basin in the last. 50 years is ascribed to both physical and economic lirr.itations on the availability of ....ater. By 1920 oost of the lo....er cost and more easily constructeci -ievelopments ....ere in operation, and, although some new devel- opments have taken place since ~h8t time, they have been partially offset by other acrea/"cs goinf'; out of production. Irrig~tion ~evelopmen~ began in the Lo....er Basin about the sa~e time as in the Upper Basin. Development ....as 510.... bec'1llse of -lifficult diver- sions from the Color~1o River with its widely fluctuating flows. Devel- opreent of the Gila area. began in 1875 and the Pnlo Ve:;de area in 1879. Construction of the Boulder C~yon Project in the 1930's and other uown- stream projects since that time has provided the means for a continued expansion of the irrigated area. In 1970, there ....ere nearly 810,000 acres irri~ated from Colorado River diversions belo.... Hoover Dam, About 25,500 acres of Lo....er Basin lands in Utah and 12. ()(X) in Nevllda are also now under irrigation. An a1ditional un~~own acre~~e is irripated by pri- vate pUI:lping from ....ells in the river ':l.quifers in ~he Lo~r Colorado River Basin. B. Strea~low Derletions Development ~~d utilization of the basin's water resources result in depletions of strearrSlo....s. ~on~p:ive use of water by irrigated crops a~d exports to other basins produce the greatest flo.... 1epletions. Reservoir evapor~tion and consumptiv~ use of ....a~er for ~nicipRl and in- dustrial purposes also Froduce significant depletions. The present esti~ated consllrnT,tive use of ....ater by irTigate1 crops in the Upper Bas:.n s","erllf,es about 1. 700. O<X> acre -feet ann':lall::. This is 10.... in cor::pcu-iscrl to the irriga.ted acreage. but some lands do not receive a f\lll sUPP~'. "ther 1~pletions related to irrigation such as: evapora- ~ion !~om irrigation reser.oirs (not Colorado River Storage Project Res- ervoirs) and incidental uses are esticated to be about 400.000 acre-feet per year. 11