GENERAL46046 - Laserfiche WebLink

Home Browse Search

• Cumulative Hydrologic Impacts The Trapper PSine is one of I2 existing or proposed coal mines in the Yampa River basin in Colorado. Only one other mining operation (Eagle !~~ and l-9 Pfines) is within 5 miles of the Trapper minesite. The next closest mines are more than 10 miles away. The consulting firm, Kaman Tempo (1982), prepared a cumulative hydrologic assessment of the impacts from coal mining on surface water in the Yampa River Basin. In the vicinity of the Trapper PSine and on downstream, they concluded that these sines genera]ly would have negligible impacts on average flow conditions in the Yampa River. Only during extreme low-flow events (which might not occur during the life of the Trapper Ptine) would any significant impact occur. During periods of extreme low flow, the TDS concentrations could increase to the point that they would cause a high salinity hazard relative to irrigating crops and would make the water unsuitable for municipal use unless it were treated. The State Recreation and Aquatic-life Water Quality Classifications of the Yampa River (Colorado Department of Health, 1983) which are not based on TDS concentrations, would not be affected. Because the Trapper Mine does not significantly impact flow in the Yampa River, its contribution to this cumulative impact is minor. The Yampa River's average low flow (July-September, 1977) was 37 cfs; for the same period, average low flow from the Trapper Mine was 0.01 cfs. Thus, Trapper Mine's contribution during average low-flow conditions is 0.03 percent. • Only the Eagle Ik5 and 1~9 mining operations could react with the Trapper Mine [o cause cumulative impacts to the ground-water system in the area. Seepage at both mines will lower the water level in the third White Sandstone. Although the areas of water-level decline are not expected to overlap, the extended area of water-level decline coupled with the slight degradation of the water quality from the Trapper Mine could limit the use of this aquifer in the vicinity of the mines. However, several other suitable aquifers in the area are available to meet demands. References Cited: Colorado Department of Health, 1983, Classifications anti numeric standards for Lower Colorado River Basin: Water Quality Control (:ommission mimeographed report. Y,aman Tempo, 1982, Cumulative hydrologic assessment: effects of coal mining on the Yampa River Basin, Moffat, Routt Counties, Colorado: mimeographed report prepared for the Office of Surface ?lining and the Colorado PSined Land Reclamation Division. • -13-