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February 2000 Summary Page S-9 <br />developed in this zone; however, numerous seasonal springs and seeps issue from these zones and <br />have been developed for livestock watering and also support wildlife. - <br />The primary bedrock water-bearing zones in the Norlh Fork of the Gunnison River Basin are in the <br />sandstone and conglomerate units and fractured zones of the Lower Cretaceous Burro Canyon <br />Formation and the Late Cretaceous Dakota Sandstone. Minor groundwater occurrence is reported in <br />the Late Cretaceous Mancos Shale, Mesa Verde and Tertiary Wasatch formations. Well yields from <br />these formations range from about 0.5 to 25 gpm, with a typical average of approximately 10 gpm. <br />Water quality from bedrock wells is generally sodium bicarbonate/sulfate type with TDS concentrations <br />ranging from 490 to 8,200 mgll, averaging about 2,569 mgll. Concentrations of sulfate, TDS, <br />manganese, and Fluoride typically exceed federal drinking water guidelines. <br />Past and current mining activities have affected groundwater quantity and quality in the region. For <br />example, mine discharge from the abandoned Oliver Mine and the abandoned Hawk's Nest Mine has <br />somewhat elevated levels of TDS, iron, and manganese. Past and current activities other than mining <br />have also affected groundwater quality. Livestock grazing causes minor impacts to springs and seeps <br />due to erosion, sedimentation, and water quality (i.e., fecal coliform). Unauthorized off-road vehicle <br />use also causes erosion and sedimentation that affect spring and seep areas. Rural septic systems <br />may impact local groundwater quality. <br />Environmental Consequences - Exploration activities should not noticeably impact groundwater <br />resources. The strata are not uniformly saturated, so there is little concern for inter-strata <br />communication. The drill holes would be small diameter and cause little disturbance to the strata. <br />Longwall mining of the lease tracts would cause bedrock fracturing and land subsidence above <br />longwall panels. By potentially providing pathways for groundwater to move downward toward the <br />mine horizon, fracturing and subsidence may divert water from saturated horizons and surface water <br />bodies above and adjacent to caved areas. Impacts to groundwater systems may resulf in a decrease <br />in natural discharge rates from springs and seeps or changes in water levels and yields in area wells. <br />Mining would dewater the coal horizon and water saturated horizons immediately above and below the <br />coal horizon. Degradation of water quality could occur when groundwater flows through active or <br />abandoned mine workings. Diversion of groundwater resulting from dewatering of the coal seam could <br />also occur as a result of underground mining. Water rights could be affected if area spring flows and <br />associated pond levels are diminished. There is also a potential for increased sedimentation to area <br />springs from construction and use of surface facilities (exploration drill pads and associated aooess <br />roads). <br />After mining, mine voids could fill with groundwater. The groundwater would be exposed to collapsed <br />and abandoned mine workings, and the quality of the water may be impacted. The most likely impact <br />would be an increased concentration of TDS, iron, manganese, and possibly sulfate. The groundwater <br />flow direction in the coal seams of the lease tracts is to the northeast, beneath the Grand Mesa. There <br />are no known wells or springs down gradient of the lease tracts that could be affected by any possible <br />groundwater degradation. <br />S-3.7 Vegetation <br />Existing Conditions -Eight upland vegetation types were mapped a1 the reconnaissance level within <br />and surrounding the coal lease tracts and exploration license area. These vegetation types include the <br />following communities: <br />Oak <br />Aspen <br />Fina/Environmental Impact Statement <br />