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Cumulative Hydrologic Assessment - Summary and Findings In lower Middle Creek, stream flow and total dissolved solids concentrations would increase primarily as the result of backfilled spoils discharges and secondarily as a consequence of discharge from the underground mine workings. Water from Middle Creek is used for irrigation. However, as shown on Map 15, water is diverted upstream of the reach that would be affected by mining. The proposed Foidel Creek underground mine would have no adverse effect upon water use in this area. Water from Fish Creek is also used for flood irrigation. The analysis indicates that the total dissolved solids concentrations would not exceed the use criteria (2000 mg/1) during the low flow months (August through September) of dry years. The long-term effects of mining, primarily discharge of affected ground water, are directly added to surface flows. In reality, ground water discharge is to the stream/alluvial aquifer system. Flow in the alluvial aquifer would help to buffer the effects of mining. Both surface and alluvial ground water quality would be degraded, but surface flows would not be affected to the extent predicted by the analysis. The water quality on Fish Creek would still be within acceptable limits to support existing and potential water uses. Lower Trout Creek and the adjacent Yampa River are used for both flood irrigation and domestic water. The projected effects of mining would not limit these uses. • A cumulative hydrologic assessment of the proposed mining operation and all anticipated mining on the hydrologic balance in the general area of the Eagle Mines has been made by the Division. This assessment has considered the short-term and the long-term effects of mining to the surface water and ground water hydrologic systems. Pursuant to Rule 2.07.6(2)(c), the Division finds that the proposed operation has been designed to prevent material damage to the hydrologic balance outside the permit area. • -46- .s