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• The water table aquifer of Ennis Draw generally follows the fall of the land surface <br />toward the north. The piezometric surface of the Laramie Shales slopes toward <br />the northeast (Appendix I-l, McWhorter, page 27 and Appendix I-2). The coal <br />piezometric surface possesses a northwesbsoutheast oriented divide (Appendix I- <br />l, McWhorter, page 28). Both of the latter two aquifers are believed to discharge <br />in the lower depths of Ennis Draw. <br />Water Ouality <br />Water quality data has been accumulated from all aquifers (Appendix [-l, <br />McWhorter, Page 29 through 35 and Appendix J-1). Generally, the waters in the <br />Laramie Shales and the target coal would be unacceptable for most uses. The total <br />dissolved solids concentrations were from 1500 to 7000+ mg/1. In addition, the <br />sodium absorption ratios (SAR) were 10 to 18, making the water mostly <br />unsuitable for irrigation. The Fox Hills water possessed TDS of 650f mg/1, while <br />Ennis Draw ground-water TDS is 750 - 1000 mg/l . <br />Existin_ Uses <br />Existing uses of ground water in the project area are for domestic supply and <br />livestock watering. Data collected from 24 wells (Appendix I-1, McWhorter, Page <br />• 100) indicated that all ground water for such uses are derived from the Ennis Draw <br />alluvium and the Fox Hills Sandstone. Water likely is not utilized from the <br />Laramie shales or coal due to its poor quality. Refer to Appendix D-1 for map <br />showing locations of wells in the vicinity of the extension area. <br />There are no water supply intakes, ditches, reserves or other surface water bodies <br />within a one mile radius of the affected area. In addition, there are no irrigation <br />ditches, or constructed or natural draws within the proposed extension area. <br />Surface Water <br />The mine is located adjacent to Ennis Draw, a tributary to Box Elder Creek which <br />flows into the South Platte River near Kersey, Colorado. There is no evidence of <br />surface runoff in the vicinity of the site. Essentially all precipitation infiltrates the <br />highly permeable mantle of sand. No water-formed erosional features are evident, <br />not even small rills or gullies. Ennis Draw is a broad, flat bottomed depression <br />with no observable channel or gully and shows no evidence of the existence of <br />surface flows. <br />• <br />50 <br />