2020-06-24_REVISION - C1981035 (2)

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ENVIRONMENTAL ASSESSMENT be backfilled and covered with topsoil.The valley floor would be restored to near original conditions using HDPE liners and gravel. Direct and Indirect Effects The Gulch low-cover crossing would be constructed in bedrock and therefore would not be expected to impact ephemeral or intermittent flow in The Gulch. The stream crossing of The Gulch would involve trenching in the valley floor and significant disturbance of The Gulch during construction activities. The valley floor of the Gulch would be restored to near original condition following construction of the Gulch crossing.The proposed disturbance of the valley floor of The Gulch would potentially affect storm water flow during periods of heavy rainfall during construction. Temporary diversion of this storm water flow around the construction area and then back into the Gulch would be required. Impacts to surface water resources in The Gulch would be minor to moderate, short-term, and local. No significant change in the proposed mining rate is expected, suggesting that ditch water consumption by GCCE should remain relatively constant. Any decrease in the use of ditch water by GCCE would be temporary and have minimal effect on ditch water flows. Consequently, no impact on surface water quantity is expected from the proposed expansion of the King Il Mine. Impacts to surface water flow in East Alkali Gulch due to the stream-bed crossing is possible during periods of heavy rainfall that may produce temporary flow in East Alkali Gulch. No large scale change in the mining rate is expected, suggesting that the Proposed Action would not impact the existing water balance for groundwater, as the mine would not require mine dewatering. Therefore,groundwater quantity should not be impacted. Groundwater in Alkali Gulch is at a depth of 36 to 40 ft. Trenching in Alkali Gulch is expected to stay above the groundwater table and thus impacts to groundwater quality are not expected. As such, impacts to groundwater resources would be negligible, short-term, and local. In addition, no impacts would be expected to nearby residential water wells. For a more detailed description of the potential direct and indirect environmental impacts, please see Section 2.3.1 of the TRR(OSMRE and BLM 2019). Cumulative Actions and Effects Cumulative effects for water resources would revolve around: 1), the Mormon Reservoir, 2), additional water needs if other coal mining expands in the area, and 3), domestic, agricultural, and livestock use of surface and groundwater resources as residential and agricultural growth continues in the CIAA. For surface water, increased diversion of water from the La Plata River would be a cumulative effect. For groundwater, agricultural and domestic use of water from the Hay Gulch alluvial aquifer and from the Point Lookout Sandstone aquifer would be cumulative effects. Because mining does not use groundwater, increased mining demand for water would affect mainly surface water because of the potential for increased diversion of water from the La Plata River. The Proposed Action, because it would not involve an increase in demand for surface water beyond what is currently occurring and does not impact groundwater would not be expected to contribute to cumulative effects for water in the CIAA. Dunn Ranch Area Coal Lease by Application COC-78825 and Mine Plan Modification EA 3-15