2011-08-09_REVISION - C1981019 (10)

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• • RULE 4 PERFORMANCE STANDARDS • Morgan and Straight Creek All of these creeks /gulches, except for Good Spring Creek and Wilson Creek, have their headwaters in the upper reaches of the topographic high that define the southern limits of the Colowyo active and proposed mines. These five creeks /gulches can be classed as ephemeral, i.e., there is no water flow in the upper reaches of the valleys except for times of rainfall or snowmelt. Downstream, they could be classified as intermittent. All are feed by springs from the bedrock. These springs are prevalent in the spring and mainly disappear by late fall, thus reducing flow in the creeks and gulches to near zero or no flow conditions. Again, like the deeper groundwater, there is no up -dip shallow ground in these valleys that can be measured for quality. Since there is no up -dip water to measure for water quality, no comparison with water from the valley fill material north of the Colowyo permit area is possible. The headwaters of Wilson and Good Spring Creeks are located in the upper portion of the Danforth Hills, south of Colowyo. These creeks tend to be perennial with the water obtained from surface runoff from precipitation and numerous springs. As with the other creeks in the area, water flow tends to decrease in the late summer through winter. The headwater for Good Spring Creek is near Ninemile Gap, approximately five miles south of Colowyo. This creek, as it flows to and past Colowyo, is fed by numerous valleys on the east side of the valley that transmit water into Good Spring Creek. Colowyo has no control of this water, which flows past old coal mines and over livestock grazing areas. The major tributary on the west side of Good Spring Creek is the West Fork. This drainage starts near the Wilson Uplift (part of the Danforth Anticline) and drains to the north and east, past the South Taylor mine area. As the creek flows north, it crosses the Collom syncline and crosses both the Iles formation and the underlying Mancos Shale. When Good Spring Creek flows through the Mancos Shale, it is passing the northern portion of the Colowyo permit area. Thus, point of compliance monitoring for ground water is not possible since approximately half the drainage area is outside of the control of Colowyo. In addition, since the Good Spring Creek valley crosses several distinct geologic formations, water quality can be affected by this change in geology, due to the fact each formation was deposited under different circumstances, which could affect water quality. The Wilson Creek valley has similar characteristics. However, it crosses Iles formation from the south before crossing over Williams Fork formation when it enters the southern Colowyo permit boundary. As it flows north, the creek crosses the Collom syncline and past the Iles formation and onto the Mancos Shale when it leaves the permit boundary. Therefore, like Good Spring Creek, the geologic conditions of the area preclude point of compliance monitoring in Wilson Creek. Water Quality The quality of the water in the area of the CM was rated as poor by the USGS in the 1970's and the water designated for iiinited agricultural use. Since USGS testing in 1978, water quality Collom — Rule 4, Page 20 Revision Date: 8/5/11 Revision No.: PR -03