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Biological Assessment <br /> Federal Coal Lease Modification(COC-62920)and Federal Mine Permit(CO-0106A)Revision and Renewal <br /> The CDPHE evaluated Hg (Snake River cutthroat trout only)tissue concentrations in Snake <br /> River and Rio Grande cutthroat trout at the Eleven Mile, Rio Grande, and North Lake reservoirs <br /> in Colorado between 2008 and 2014 (CDPHE 2017). The mean Hg tissue concentrations for the <br /> Snake River cutthroat trout was 0.11 mg/Kg at Eleven Mile Reservoir (95 miles northwest of <br /> Pueblo). Rio Grande cutthroat trout sampled for Hg concentration at the Rio Grande Reservoir <br /> (225 miles southwest)were found to be approximately 0.15 mg/Kg. The lowest concentration <br /> levels in the Snake River cutthroat trout were 0.41 mg/Kg sampled at North Lake, 90 miles south <br /> of Pueblo. (Lepak et al. 2012). These studies suggest Hg baseline concentration levels for the <br /> cutthroat trout are below the USGS BEST concentrations that affect fish health. In addition, <br /> these baseline Hg concentrations evaluated by CDPHE do not exceed adult fish Hg body burden <br /> benchmarks of 0.20 mg/kg wet weight(Beckvar et al. 2005) and 0.8 mg/kg wet weight(AECOM <br /> 2013 as cited in USFWS 2014). These adult fish body burden benchmarks are intended to <br /> represent tissue burdens below which adverse effects in fish are unlikely (USFWS 2014). <br /> In 2006, rainbow trout(a related salmonid species)were collected at Runyon Lake, Pueblo, <br /> Colorado.' These trout samples (fillets) were analyzed for mercury. No rainbow trout samples <br /> exceeded the adult fish Hg body burden benchmark of 0.20 mg/kg wet weight. In 2013, several <br /> fish species were collected in Runyon Lake and Pueblo Reservoir, Pueblo, Colorado.2 These fish <br /> samples (fillets)were also analyzed for mercury. From these recently collected fish, no samples <br /> exceeded the adult fish Hg body burden benchmark of 0.20 mg/kg wet weight.3,4 <br /> Because emissions of mercury from the Pueblo plant are about half of those from the Tij eras <br /> plant, and because known populations of greenback cutthroat trout are more than twice the <br /> distance from the source, it stands to reason that mercury concentrations in cutthroat trout tissue <br /> would not be elevated to a level causing injury or impairment to this species. Therefore, the <br /> determination of effect for the Proposed Action is may affect, not likely to adversely affect the <br /> greenback cutthroat trout. <br /> 6.2.3 Colorado Pikeminnow and Razorback Sucker <br /> The effects of mercury deposition on these species is thoroughly documented in the <br /> FCPP/NMEP BO (USFWS 2015). The very small release of less than 0.25 pound per year of <br /> mercury associated with combustion of King II coal by the DSNGRR has been occurring for <br /> 1 https://www.colorado.gov/pacific/sites/default/files/RunyonLake.pdf <br /> 2 https://www.colorado.gov/pacific/sites/default/files/RunyonLake.pdf <br /> https://www.colorado.gov/pacific/sites/default/files/PuebloReservoir.pdf <br /> s Note that fish collected and analyzed in 2013 included smallmouth bass,spotted bass,walleye,black crappie,saugeye,and <br /> channel catfish—none of these species are salmonids. <br /> 4 Saugeye caught in 2006 were the only fish that slightly exceeded the adult fish body burden benchmark. <br /> July 2017 <br /> 33 <br />