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February 2000 Chapter 3 Page 3-55 <br />SW-9 - Monthty monitoring of flow and quality should be established on Bear and Etk creeks <br />above and below the expected zone of influence from mining the Elk Creek Coal Lease Tract, <br />and this type of monitoring would probably be required under a future mine permit. <br />3.6 GROUNDWATER <br />Issue: Identify and minimize impacts to water quality and hydrology to maintain the integrity of <br />watersheds within and surrounding the lease tract areas. Maintain adequate flows to drainages <br />and ditches above underground mining activity. Areas of concern include: the potential to alter <br />existing hydrologic systems; alteration of downstream flow rates; alteration of existing springs <br />and seeps; changes in water chemistry as a result of mining operations; and, impacts to water <br />rights on Terror Creek, Hubbard Creek, Bear Creek, and Elk Creek. <br />3.6.1 Introduction <br />The study area for groundwater hydrology includes the region within a 1 mile radius of the <br />proposed coal lease tracts and the exploration license area. Particular attention was given to <br />the area of potential subsidence induced impacts (see Figure f4, Subsidence Potential Map). <br />The analysis of groundwater hydrology includes wells, springs and seeps, and stockponds fed <br />by springs. Springs are defined as flowing at a rate of greater than or equal to one gallon per <br />minute (gpm). Seeps flow rates are less than one gpm or are not measurable. <br />Information for this evaluation was derived from the following sources: <br />Groundwater quality and quantity data for area wells and springs from Bowie, <br />Oxbow, USGS, and Hotchkiss Ranches, as well as on-the-ground site visits by the <br />North Fork Coal EIS team; <br />Water rights information within a 1 mile radius from the Iron Point and Elk Creek. , <br />Coal Lease tracts and Iron Point Exploration License area from the Colorado State <br />Engineers Office, Division of Water Resources; <br />Review of Bowie and Oxbow data, annual hydrology reports, permit applications, and <br />consultant reports related to groundwater hydrology; <br />Regional NEPA documents; and, <br />Review of reports, data, and maps compiled by the USGS, Colorado DMG, Forest <br />Service, and BLM. <br />3.5.2 Affected Environment <br />3.5.2.1 Regional Hydrogeology <br />The primary groundwater-bearing zones in the North Fork of the Gunnison River Basin occur in <br />Quaternary alluvial, colluvial, glacial, and eolian deposits and Cretaceous bedrock. Alluvial <br />deposits along the North Fork of the Gunnison River are saturated and considered to be an <br />aquifer. The municipal water supply for the town of Paonia is derived from colluvial springs <br />located on the north side of Mount Lamborn, across the North Fork of the Gunnison River <br />Valley from the project area. Alluvial water-bearing units are thickest in the axis of the drainage <br />bottoms and are typically 100 feet or less in thickness. The water quality of the alluvial <br />groundwater is calcium bicarbonate type and is of good quality. The TDS concentrations of the <br />