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Evaluation of Potential Subsidence Impacts of Longwall Mining in the Spruce Stomp Lease Area <br />to Aquatic Life and Water Supply <br />The observed presence of cutthroat trout in West Fork Terror Creek dates to at least 1978, when <br />Colorado Division of Wildlife (CDOW) sampling efforts yielded cutthroat trout and speckled <br />dace at two locations near the up- and downstream end of West Fork Terror Creek as it flows <br />through the Spruce Stump Lease Area. The lower location (Station 1) sampling data lead the <br />CDOW to estimate that there were 4.6 pounds of cutthroat trout per acre of stream. Assuming an <br />average channel width of 20 feet, with would roughly equate to 11 pounds per mile. The upper <br />location (Station 2) sampling data lead the CDOW to estimate that there were 0.8 pounds of <br />cutthroat trout per acre of stream. Assuming an average channel width of 20 feet, this would <br />roughly equate to 2 pounds per mile. The underlying cause for the difference in fish densities is <br />not readily apparent based on available data and notes from this work. Although the watershed <br />was not impacted by coal mining or drilling activities in 1978, impacts related to the installation <br />of the Curecanti -Rifle powerline were present. <br />Following the 1978 sampling effort, more than two decades passed before the next available fish <br />sampling efforts were conducted in 2005 by the USFS. This sampling effort examined West <br />Fork Terror Creek and Cunningham Creek (a tributary to West Fork Terror Creek that is located <br />upgradient from the Action Area). These sampling efforts identified 166 adult Colorado <br />cutthroat trout per mile in West Fork Terror Creek and 245 adult Colorado cutthroat trout per <br />mile in Cunningham Creek. These two populations were assigned genetic purity ratings of "A ", <br />indicating low rates of hybridization with other cutthroat subspecies or rainbow trout. <br />The USFS conducted additional West Fork Terror Creek fish sampling in 2010. This sampling <br />occurred following publication of genetic research that reported a genetic signature shared by the <br />federally listed greenback cutthroat and certain cutthroat trout found in the Grand Mesa, <br />Uncompahgre and Gunnison National Forest areas (GMUG). The GMUG cutthroat trout that <br />shared this genetic signature with greenback cutthroat trout were identified as GB- lineage <br />cutthroat trout. The 2010 sampling efforts resulted in estimates of 652 +/- 61 fish /mile and 267 <br />+/- 58 adult fish /mile at a lower West Fork Terror Creek sampling location and 678 + /- 58 <br />fish /mile and 117 +/- 21 adult fish /mile at an upper West Fork Terror Creek sampling location. <br />In addition to fish density measurements, this study included genetic analysis to identify the <br />121 - 014.000 Wright Water Engineers, Inc. Page 12 <br />January 2013 <br />