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<br />The Uppei "Colorado River
<br />National Water-Quality Assessment Program
<br />Surface-Water-Monitoring Network
<br />
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<br />\ ~pper ('nlmadu Ri\'l'r
<br />BaslIl Stud\ t :nil
<br />(shown in'" red I
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<br />:--JatillnaJ N,\ \\'<)1\ Stud\' Units
<br />(shown In f!laYl.
<br />
<br />
<br />Phlltogral'h hy John Lllioll
<br />
<br />uL~
<br />GfS
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<br />U.S, Department of the Interior-U.S. Geological Survey
<br />
<br />INTRODUCTION
<br />The U.S. Cieological Survey hegan full imple-
<br />mentation of the National Water-Quality Assessment
<br />lNAWQA) program ill 1901. The long-term goals of
<br />tht' \JA WQA program arc to \ ] I dc:.;crihc currcll!
<br />\'..Iater-quality conditions for a large part of the
<br />Nation's frcsll\vater streams, rivers. and aquirers;
<br />(2) describe 110W water quality is l'hanging over
<br />lime: ami (-,) improve understanding or the primary
<br />natural and human (actor:-, that Jrf~ct vl-'atcr..quality
<br />c(mditions (L.eahy and ()lhcJ".-.. 11)00). To meet thc:-,c
<br />goab, 60 study units representing the Nation's most
<br />important river basins and aquifers arc being investi-
<br />gated ThL' program design balances the unique
<br />.lss('.ssmcnt requiremcnts (If individual study units
<br />with ,I nationally consistent design structure that
<br />illcorpnraks a lIlultiscalc, interdisciplinary approach
<br />for aSSL'SSlllcnt of surfa>:e and ground water
<br />
<br />The UppL'r Colorado River Basin (UCOL) is
<br />one of the 60 NA WQA study units; hydrologic alld
<br />water-quality aSSCSSIllL'nts of the UCOL began in
<br />1994. The sludy unit has il drainage area ofahout
<br />17,X(}O llli2, ,1I1Iltl1(' primary river within the basin,
<br />the Colorado Riv't.'r. originates ill the lllollllwins of
<br />cemral ('(,Inrado and flows about 230 mi southwest
<br />into Utah. l'vlajor tributaries 10 lhe Colorado River III
<br />the study unil arc the Blue, Eagle. Roaring Fork.
<br />.\llll GUllnisoll Rivers. The Colorado River is (he
<br />major supply of \}o.'ater to the soulhwestern United
<br />State.s. Streamllow from lhe study unit <lccounts for
<br />anout 40 percent of Ihe strcamtlo\'.! of the Colorado
<br />River al Lees Ferry.
<br />
<br />The UCOL study L1nit is divided almost equally
<br />into two physiographic provinces- -thc southern
<br />Rucky Mountains in t11l' eastern pari and the
<br />Colorado Plateau in the western part. The Southern
<br />Rocky Nloulllain province is characterized by north-
<br />northwest-trending moulltains of crystalline rocks
<br />that range in elevation from 11,00010 more than
<br />14,000 ft. .I'he Col()rado Platcau pn,vincc consists
<br />of high platL'all.'" of scdimelllary n)Cks \vith e1eva-
<br />lions ranging from ahout 5..500 to ~,50() ft.
<br />
<br />Land use, c1assilicd as rangeland or forest.
<br />accounts for about X5 percellt of Ihe basin. The other
<br />major land uses in Ihe basin are agriculturc. mining,
<br />and urhan. Surface water used for irrigation
<br />accounts for ahout 07 percent or the total olTstream
<br />waleI' use. A sllrface-watcr-.moniloring netw(lIt. for
<br />Ihe UCOI study unit was designed considering the
<br />critical natural and human factors that affect surface--
<br />water quality in the basin.
<br />
<br />WATER-QUALITY ISSUES
<br />
<br />The following walcr~quality isslIcs in the
<br />UCOL study unil have heen idenlified as high-
<br />priority local-scale issues of concern to Slate and
<br />local water-resource managers.
<br />
<br />-Effects of increasing urban devclopment
<br />-Effects of hydrologic modifications
<br />-Effects of metal mining
<br />-Effects of nonpoint- and point-agricultural sources
<br />-Effects of salinit:' from natural. agricultural, and
<br />municipal sources
<br />A national scale synlhesis of the rcsulls
<br />generated by each NAWQA study lIllil is an inte-
<br />gral component of the NA WQA program. The
<br />national syl1lhcsis allows a comprehensive assess-
<br />mcnt of specific water-qualilY issues al a national
<br />scale by comparative analysis of individu<ll sludy.
<br />unit tlndings. National synthesis has identified
<br />pesticides, nutrients, and volatile organic contami
<br />nants to he the most importanl nalional water-
<br />quality issues. These local and national issues will
<br />partially be addressed by the use of a network of
<br />surface-water monitoring stations in the UCOL
<br />study unit.
<br />
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<br />EXPI A~ATlON
<br />COllllt" Bnllnuary
<br />-llit,inllolll1dary
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<br />o :ro ~OM!lE'.S
<br />f--.--'-r- J
<br />o 20 401lll0METERS
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