2018-07-09_PERMIT FILE - C1981019A (58)

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RULE 2 PERMITS Surface Water Occurrence of Surface Water General Area The surface water of the general area is characteristic of a high altitude environment. The climate is semi -arid, characterized by low precipitation, large daily temperature changes, low humidity, moderate winds and abundant sunshine. Precipitation averages 21.5 inches across the drainages in the "general area" per year resulting in erratic and low flows in the major drainages near the mine area. Climatic data is discussed in detail in Section 2.04.8. Surface flows are dominated by the occurrence of runoff events resulting from either snowfall or rainfall. Snowfall derived runoff dominates the hydrologic cycle, supplemented by periodic intense thunderstorms which result in flashy flow conditions. The quantity and quality of the surface water also reflects the high evapotranspiration rates and the predominance of sandstones, shales and coals in the basin. See Section 2.04.6 for a description and discussion of the geology in the Colowyo Mine area. The mine area is drained by Streeter Gulch, an ephemeral tributary to Goodspring Creek which is a perennial stream located east of the mine area, and by an unnamed tributary to Taylor Creek, an intermittent stream west of the property. Goodspring Creek flows northward to its confluence with Milk Creek. Taylor Creek flows northward to where it joins Wilson Creek, a perennial stream which continues northeastward to its confluence with Milk Creek. Milk Creek has a mean annual flow of approximately 20,000 acre feet and is a southern tributary of the Yampa River which rises along the divide between the Yampa and White Rivers. Milk Creek flows in a generally northerly direction to enter the Yampa approximately 14 miles downstream from Craig, Colorado. The mean annual flow of the Yampa River at the Maybell Gage situated downstream of the area of interest is in excess of one million acre feet per year. The Yampa River is tributary to the Green River which enters the Colorado River in Utah. See Map 32 for locations of the surface drainages. Permit Area The streams of concern for the Colowyo Mine include Taylor Creek, Streeter Gulch, Wilson Creek and Goodspring Creek. Taylor Creek and Streeter Gulch are intermittent and ephemeral drainages, respectively; Wilson and Goodspring Creeks are perennial streams. Surface water has been studied extensively since 1973 by various investigations. These investigations include the EMRIA Program sponsored by the Bureau of Land Management (BLM) and conducted by the USGS. Additionally, the Colowyo Coal Company, and its consultants have conducted monitoring programs for various parameters during the recent past. The USGS has continuously monitored several of the drainages, including Taylor, Wilson and Goodspring Creek, for flow volumes and quality parameters. Colowyo Coal Company and its consultants have also monitored the USGS stations as well as additional stations in and adjacent to the mine area. Limited sampling has also occurred on drainages outside the general and adjacent areas. These sample stations were located on Collum Gulch, Straight Gulch, Jubb Creek, and Milk Creek. The data for these stations are not analyzed here but are presented in Exhibit 7A. Rule 2 Permits 2.04.7-10 Revision Date: 4/7/17 Revision No.: RN -07