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2.04.7 Hydrology Description <br />(b) The subsurface hydrologic regime may be divided into four discrete subsystems: 1) <br />the alluvium and terrace deposits associated with the North Fork of the Gunnison <br />River; 2) localized deposits of alluvium -colluvium within the Hubbard Creek, and <br />Terror Creek areas; 3) groundwater occurrences within the Mesaverde Formation; 4) <br />colluvial discharges associated with soil moisture storage in Steven's Draw, C -Gulch <br />and at the head of Freeman, 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 section <br />2.06.8. The State Engineer's records depict 3 registered wells completed within the <br />alluvium located in Sections 14, and 15, T.13 S., R.92 W., 6th P.M. (Bowie No. 1 <br />Mine Area) <br />These wells range from 14 feet to 77 feet deep and typically produce water from 12 <br />feet. The well yield ranges from 5 gpm to 120 gpm with average yields of <br />approximately 17 gpm. Water quality is highly variable within the alluvial fill. Most <br />wells completed near the river sustain quality adequate for human consumption; <br />however, the higher sulfate and total dissolved solids values are probably a function <br />of return irrigation flows and well completion depths near the alluvium-Mancos shale <br />contact. <br />Localized Alluvium -Colluvium <br />Localized deposits of alluvium -colluvial material reworked by fluvial processes are <br />present within the area, primarily within the Hubbard Creek, and Terror Creek <br />drainages. Hydrologic testing in similar material performed by Colorado <br />Westmoreland Inc. (CWI) during development of their Steven's Gulch well field <br />showed that yields from these sources are moderate (27 gpm at Steven's Gulch well <br />field), with transmissivity values ranging from 187 to 230 sq. ft. per day, and storage <br />coefficient of 0.0002. Water from wells penetrating this lithotype are classified as <br />sodium bicarbonate (Brooks, 1983). Recharge is accomplished from precipitation <br />and run-off, and water is discharged from seeps or springs. Although similar in some <br />respects, these areas do not fulfill the requirements of being Alluvial Valley Floor <br />areas. <br />Several years of water table monitoring in the CWI wells installed in the Stevens <br />Gulch indicated the water level in this aquifer is below the local streambed for most <br />of the year, and therefore the streams are recharging the aquifer. <br />TR -99 2.04-37- 03/16 <br />