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<br />o <br />CO <br />C Table 7. General hydrologic description of selected aquifers in the Upper Colorado River Basin study unit <br />j-l. <br /> <br />[0. leel; gal/mill. gallons ~r minulc; mg/L. milligrams per Iller: n1/d. feet squared per day: n. no dala. Data from Wilson. 1965: m(Jdified from <br />U.S. Geologi..:al Survey. 1985: and from Warner and others. 19S5] <br /> <br />Aquller name and description <br /> <br />Remar1ts <br /> <br />Aquifer <br />thickness <br />(It) <br /> <br />Polenll", <br />yield <br />(gel1mln) <br /> <br />DIssolved- <br />solido <br />(mg/L) <br /> <br />Tran!t- <br />mloolvlty <br />(1t2/d) <br /> <br />Allu\'lal aquifers: Boulders.. <br />cClbbles. grovel sand. silt, and clay: <br />unconsolidated and only moderately <br />sorted. Generally unconfined. <br /> <br />Green River aquifer: <br />Upoer aauifer: coarse- 10 fine-grained <br />silty sandstone and siltstone of the <br />Uinta Forrn.alion and fractured dolo- <br />mite marlstone. Generally confined. <br /> <br />Lower aquifer: Fradured dolomitic <br />marlstone. <br />Generally confined. <br />Mesaverde _qulrer: Murine sandstone <br />with interbedded sills{one and shale: <br />coal bearing in middle pan of group. <br />Confined. except near outcrop areas. <br /> <br />MlIncos Shllle unit: Silty and sandy <br />Jrultine shale: conlains some inter- <br />bedded sandstones and limestones. <br />Unconfined. <br /> <br />Dakota aquifer: Snndst(lne with intt:r- <br />bedded siltstone and curbonaceous <br />shale: contains many <br />conglcnnerate lenses near base. <br />Confined. <br />Morrtson .qulfer: Fine- 10 medium- <br />grained. thin-bedded sandstone. and <br />varicolored red and green shule. <br />Entrada aquifer: Medium. to very <br />fine- grained sandstone with so~ <br />silt and clay. Confined. <br /> <br />Leadville aquifer: Gray dolomitic <br />limestone with some sandstone and <br />chert. Confined. <br />Precambrian crystalline unit: Quartz- <br />biotite gneiss and schist with some <br />hornblende gneiss and quartzite: <br />intruded by granite and quar17. <br />monzClnite batholiLhs and other <br />intrusives. Unc(mfined. <br /> <br />20-40 <br /> <br />500-1.000 <br /> <br />600-2,000 <br /> <br />1.000-1500 <br /> <br />20-50 <br /> <br />200-1.000 <br /> <br />500-700 <br /> <br />500-700 <br /> <br />lTlay cx(:eed <br />2,000 <br /> <br />100-250 <br /> <br />UnconsoUdated aquifers <br />5-100 20CHOO <br /> <br />Bedrock aqllifers <br /> <br />]0-500 <br /> <br />2-50 <br /> <br />1-10 <br /> <br />]-10 <br /> <br />1-:!5 <br /> <br />1-25 <br /> <br />1-25 <br /> <br />ll'13y exceed <br />500 <br /> <br />0,5-5 <br /> <br />400-2,000 <br /> <br />500-40,000 <br /> <br />150-1,200 <br /> <br />200-4,800 <br /> <br />300-) .500 <br /> <br />],000 <br /> <br />500 <br /> <br />)0,000 <br /> <br />20-],600 <br /> <br />]2,000 <br /> <br />]O-{,oo <br /> <br />](}.j;OO <br /> <br />20 <br /> <br />20 <br /> <br /><10 <br /> <br />More permeable than consoli- <br />dated meks. <br /> <br />Water ex.clusively in <br />rmctures. Potential or <br />aquifer nol developed. The <br />lower aQuiJcr <br />commonly contains <br />dissolved gas. <br /> <br />Water ranges from sodium <br />bicarbonate type to <br />calcium !iulrale type. <br />depending on presence or <br />.<lbsence or shales. <br />Dissolved iron may exceed <br />National drinking-water <br />regulations. <br />Water conlained in rractures or <br />weathered zones. Wafer is <br />predominamly sodium <br />bicarbonate to sodium <br />sulfate type. <br />Many wells flow al thc <br />surface. Waler Iilngt:s from <br />sodium bicarbonate to <br />calcium bicarbonate type. <br /> <br />Water is calcium bicarbonate <br />type, <br /> <br />Wafer generally sodium bicar- <br />bonate type. Sume waler <br />contains dissolved hydrogen <br />sulfide gas. <br />Potential nfaquifer no! <br />developed. Water is a <br />sodium bicarbonate type. <br />Water available only in <br />fractures. <br /> <br />ENVIRONMENTAL SETTING 25 <br />