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. ~ ~ -~- 'The surface water quality of the San I~liguel River Basin is generally fair wiCh water type being calcium, bicarbonate-sulfate. The water is used primarily as a source of irrigation water within the region. The water quality tends to degrade in late summer near the end of the irrigation season. This can be attributed to irrigation return flows and lack of stream flow to aid in dilution. The proposed operation will afFect lUf3 acres of the Tuttle Uraw Urainaye Basin. Some of the base flow of the perrenial Tuttle Draw drainage can be attributed to irrigation return flows from adjacent farmlands. The source of the irrigation water which suppli+uents the flow of Tuttle Draw is primiarily from the San I4iyuel River. Water quality in the Tuttle Draw .is moderately alkaline with a pH between 7.5 and 8.5 for most of the year. High levels of heavy or trace elements are not experienced. However, nitrate and dissolved solids content may push the water quality into the poor category during late summer. This shift in water quality is primarily due to irrigation return flows. Ground water occurs in the Dakota Sandstone Formation, the overburden, alluvial deposits along Tuttle Draw and a shallow water table aquifer. Occurrences in the coal-bearing Uakota Sandstone Formation are extremely variable. Several small, laterally discontinuous aquifers exist within ttre overburden as well as in the alluvial deposits along Tuttle Draw. The aquifers have poor yields and poor water qualities. The most significant occurrence of ground water in the area is in the shallow water table aquifer. This shallov+ aquifer is recharged and affected by flood irrigation to the north of the mine. Under existing conditions, the irrigation return flow in this aquifer up yradient of the mine becomes degraded as it flows to the discharge point. The shallow aquifer discharges to Tuttle Uraw and degrades the water quality of this stream. The shallow aquifer has been intercepted by the mining operation on the northern pit walls. An inflow occurs on the northern pit wall along the contact between the bedrock and the weathered bedrock-soil contact. This water is channeled through the mine then discharged through pond 001. Ground water use within the region is of lower significance as~compared to surface water. Ground water is primarily used for domestic consumption, stock watering, and to a lesser extent, municipal supply. Whereas, surface water is the major municipal and irrigation water source.