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<br />VII-8 <br /> <br />. <br /> <br />dri lied into these aqui fers, and therefore, very Ii ttl<- is known regarding <br /> <br /> <br />the occurrence, movement, and recharge of water. Wate. qual ity in these <br /> <br /> <br />bedrock units has generally been found to be poor with the critical high <br /> <br /> <br />concentrations being hardness, total dissolved solid~ and sulfates. <br /> <br />The Maroon Formation crops out in a number of areas adjacent to Carbondale. <br /> <br /> <br />This formation consists of a red calcereous sandstone and shale with some <br /> <br /> <br />limestone and arkosic conglomerate. Generally, the yield is low with less <br /> <br /> <br />than 5 gF'm. In some cases, where fractures are encountered, yields of 25 <br /> <br /> <br />gpm or more have been obtained. <br /> <br />The water quality from the Maroon is generally very hard, high in sulfates <br /> <br /> <br />and in some cases, total dissolved solids are in excess of 1,100 ppm. <br /> <br />. <br /> <br />The Mancos Sh31e is the other main bedrock formation of the area. In most <br /> <br /> <br />cases, the Mancos possesses poorer quantitative and qualitative ground water <br /> <br /> <br />characteristics than the Maroon Formation. A number of drillers' reports <br /> <br /> <br />indicate less than gpm from some Mancos wells. <br /> <br />Within the massive gray shale unit lie some interbedded sandstone and lime- <br /> <br /> <br />stone. Just south of Carbondale, two successful wells have been drilled and <br /> <br /> <br />receive water from a fractured limestone. Both of these wells are about 85 <br /> <br /> <br />feet in depth. This I imestone appears to be the Fort Hayes member of the <br /> <br /> <br />Mancos. Each well has a potential yield of over 500 gpm. Water quality in <br /> <br /> <br />both cases is good, with the exception of hardness, which varies seasonally, <br /> <br /> <br />but generally exceeds 300 ppm. <br /> <br />The Dakota Formation, which is a major aquifer in southeastern Colorado, <br /> <br /> <br />also outcrops in the area. This fine-grained sandstone is found southeast <br /> <br /> <br />of Carbondale and is exposed along the flanks of Mt. Sopris. Very little <br /> <br /> <br />well data is available for the Dakota in this area. <br /> <br />Unconsolidated Alluvial Aquifers <br /> <br /> <br />Unconsolidated alluvial aquifers are normally considered those in which shal- <br /> <br /> <br />low tributary water occurs. Generally, the coarser the material, the better <br /> <br />. <br />