2010-12-17_REVISION - C1981019 (153)

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22 r 0 Monitoring locations Surface water The upper reaches of Little Collom Gulch are located within the proposed Collom Mine. As a result, an upgradient monitoring station was not established. Sampling Point LLCG is located immediately adjacent to valley fill well MLC -04 -01 east and just above the confluence of Little Collom and Collom Gulches (Figure 4.2). 4.3.3 Collom Gulch Description Collom Gulch is located near the center of the Collom study area. Above sampling point LCG, it drains approximately 5.05 square miles of hilly terrain. The elevation of the stream channel ranges from 6,457 ft amsl where it crosses Moffat County Road 51 to greater than 7,800 ft amsl near the summit of the Danforth Hills. The stream channel runs north - northeast through the Collom Syncline and then across the pediment slope north. of the syncline before joining Morgan Gulch. Collom Gulch is an intermittent stream through out its entire length. The upper and lower reaches of Collom Gulch flow in a relatively narrow valley. The middle reach flows in a flat, wide valley bottom just south of the synclinal axis. There is little sinuosity developed except in the middle reach where the channel is braided. 10 In December 2004, January 2005, and February 2005, there was no flow at the upper Collom Gulch sampling point (UCG). Flow at the lower Collom Gulch sampling point (LCG) ranged from 2.6 gpm in December 2004 to about 30 gpm in February 2005. Flow began to increase in the spring due to snowmelt and increased precipitation. In April 2005, stream flow at the upper Collom Gulch station was about 340 gpm whereas flow at the lower Collom Gulch station was about 90 gpm. This indicates that snowmelt in the upper reach is infiltrating into the Collom Gulch valley fill during the spring. In the summer and fall, this recharge probably contributes to stream flow in lower Collom Gulch as groundwater discharge to the stream. Monitoring locations Sampling point UCG is immediately adjacent to valley fill well MC- 04 -01. Sampling point LCG is immediately adjacent to valley fill well MC -04 -02 (Figure 4.2). 4.3.4 Straight Gulch Description Straight Gulch is located on the western edge of the Collom study area. Above sampling point LSG, it drains approximately 7.51 square miles of hilly terrain. The elevation of the stream channel ranges from 6,639 ft amsl at the confluence of Straight Gulch and Morgan Gulch to approximately 7,800 ft amsl near the summit of the Danforth Hills. The ( stream channel runs north - northeast across the south limb of the Collom Syncline and 0 merges with Morgan Gulch south of the synclinal axis. 2572 -R2 Colowyo Coal Company Water Management Consultants