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• 2.04.7 Hydrology Description <br />(b) The subsurface hydrologic regime may be divided into four discrete <br />subsystems: 1) the alluvium and terrace deposits associated with the North <br />Fork of the Gunnison River; 2) localized deposits of alluvium - colluvium within <br />the Hubbard Creek, and Terror Creek area; 3) groundwater occurrences <br />within the Mesaverde Formation; 4) colluvial discharges associated with soil <br />moisture storage in Steven's Draw, C -Gulch and at the head of Freeman, <br />Sheep Corral, Stevens and Dove Gulches. <br />North Fork of the Gunnison River Alluvium <br />Alluvial fill associated with the North Fork of the Gunnison River and tributary <br />drainages (Terror Creek) have been extensively developed for domestic and <br />agricultural water sources. For a discussion of Alluvial Valley Floors, see <br />section 2.06.8. The State Engineer's records depict 3 registered wells <br />completed within the alluvium located in Sections 14, and 15, T.13 S., R.92 <br />W., 6th P.M. (Bowie No. 1 Mine Area) <br />These wells range from 14 feet to 77 feet deep and typically produce water <br />from 12 feet. The well yield ranges from 5 gpm to 120 gpm with average <br />yields of approximately 17 gpm. Water quality is highly variable within the <br />alluvial fill. Most wells completed near the river sustain quality adequate for <br />• human` consumption; however, the higher sulfate and total dissolved solids <br />values are probably a function of return irrigation flows and well completion <br />depths near the alluvium - Mancos shale contact. <br />Localized Alluvium- Colluvium <br />Localized deposits of alluvium - colluvial material reworked by fluvial <br />processes are present within the area, primarily within the Hubbard Creek, <br />and Terror Creek drainages. Hydrologic testing in similar material performed <br />by Colorado Westmoreland Inc. (CWI) during development of their Steven's <br />Gulch well field showed that yields from these sources are moderate (27 gpm <br />at Steven's Gulch well field), with transmissivity values ranging from 187 to <br />230 sq. ft. per day, and storage coefficient of 0.0002. Water from wells <br />penetrating this lithotype are classified as sodium bicarbonate (Brooks, <br />1983). Recharge is accomplished from precipitation and run -off, and water is <br />discharged from seeps or springs. Although similar in some respects, these <br />areas do not fulfill the requirements of being Alluvial Valley Floor areas. <br />Several years of water table monitoring in the CWI wells installed in the <br />Stev en's Gulch indicated the water level in th aquifer is below the local <br />streambed for most of the year, and therefore the streams are recharging the <br />aquifer. <br />• <br />PR -12 2.04-33- 02/10 <br />1 VPRovr-D <br />11116110 <br />