7897 - Laserfiche WebLink

Home Browse Search

Table 7. General hydrologic description of selected aquifers in the Upper Colorado River Basin study unit [ft, feet; gal/min, gallons per minute; mg/L, milligrams per liter; ft2/d, feet squared per day; --, no data. Data from Wilson, 1965; modified from U.S. Geological Survey, 1985; and from Wazner and others, 1985] Aquifer Potential Dissolved- Trans- Aqulfer name and description thickness yield solids missivity Remarks (ft) (gal/min) (mg/L) (ftz/d) Alluvial aquifers: Boulders, cobbles, gravel, sand, silt, and clay; unconsolidated and only moderately sorted. Generally unconfined. Greeu River aquifer: Upper aquifer: coarse- to fine-grained silty sandstone and siltstone of the Uinta Formation and fractured dolo- mite marlstone. Generally confined. Lower ~uifer: Fractured dolomitic marlstone. Generally confined. Mesaverde aquifer: Marine sandstone with interbedded siltstone and shale; coal bearing in middle part ofgroup. Confined, except near outcrop areas. Marcos Shale unit: Silty and sandy marine shale; contains some inter- bedded sandstones and limestones. Unconfined. Dakota aquifer: Sandstone with inter- beddedsiltstone and carbonaceous shale; contains many conglomerate lenses near base. Confined. Morrison aquifer: Fine- to medium- grained,thin-bedded sandstone, and varicolored red and green shale. Entrada aquifer: Medium- to very fine- grained sandstone with some silt and clay. Confined. Leadville aquifer: Gray dolomitic limestone with some sandstone and chert. Confined. Precambrian crystalline unit: Quartz- biotite gneiss and schist with some hornblende gneiss and quartzite; intruded by granite and quartz monzonite batholiths and other intrusives. Unconfined. Unconsol(dated aquifers 240 ~ 100 200300 Bedrock agalfers 500-1.000 10-500 400-2,000 600•-2,000 2-50 504~I0,000 1,000•-1.500 1-10 154-1,200 20-50 1-10 2001,800 200-1,000 1-25 300-3,500 500-700 1-25 1,000 500-700 1-25 500 may exceed may exceed 30,000 2,000 500 104-250 0.~5 24-1,600 12,000 More permeable than consoli- datedrocks. Water exclusively in 1000 fractures. Potential of aquifer not developed. The lower aquifer commonly contains dissolved gas. 10-600 --- Water ranges from sodium bicarbonate type to calcium sulfate type, depending on presence or absence of shales. Dissolved iron may exceed National drinking-water regulations. --- Water contained in fractures or weathered zones. Water is predominantly sodium bicarbonate to sodimn sulfate type. --- Many wells flow at the surface. Water ranges from sodium bicarbonate to calcium bicarbonate type. 20 Water is calcium bicarbonate type. 20 Water generally sodium bicar- bonate type. Some water contains dissolved hydrogen sulfide gas. --- Potential of aquifer not developed. Water is a sodium bicarbonate type. <10 Water available only in fractures. ENVIRONMENTAL SETTING 25