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Biological Assessment <br /> Federal Coal Lease Modification(COC-62920)and Federal Mine Permit(CO-0106A)Revision and Renewal <br /> waters. No water sample drawn from any major waterway in New Mexico has been found to <br /> contain mercury at a level that could pose any degree of direct risk to humans or wildlife <br /> (NMED 2001). <br /> Arkansas River Basin <br /> The Integrated Water Quality Monitoring and Assessment Report (305(b)Report) submitted to <br /> the EPA by the Colorado Department of Public Health and Environment's Water Quality Control <br /> Division (WQCD) summarizes the water quality conditions of the state's waters. No impairment <br /> due to elevated mercury levels have been reported. Additionally, CDPHE also monitors metal <br /> toxicity levels of fish in reservoirs throughout the state in order to protect the public from <br /> consuming fish with elevated levels of toxic metals (refer to: https://www.epa. ov/wgc/national- <br /> recommended-water-quality-criteria-aquatic-life-criteria-table#table) Human health advisories <br /> are posted when a pollutant level exceed the criteria level for aquatic life ambient water quality <br /> as recommended by the Environmental Protection Agency (EPA 1985). Aquatic life criteria for <br /> toxic chemicals are the highest concentration of specific pollutants or parameters in water that <br /> are not expected to pose a significant risk to the majority of species in a given environment. The <br /> mean acute and chronic toxicity levels of mercury for freshwater fishes is 1.4 µg/L and 0.77 µg/L <br /> respectively (EPA 1985). Between 2006 and 2013, more than 48 fish tissue samples from a <br /> variety of fish species were collected from Runyon Reservoir within 5 miles of the GGC Pueblo <br /> Cement Plant. Of these 48 samples nearly all concentrations of mercury in tissue were less than <br /> 0.10 ppm. The few exceptions were samples from longer lived and larger predatory high <br /> (walleye). Composite samples of rainbow trout were all less than 0.10 ppm. In nearby Pueblo <br /> Reservoir, of 20 fish tissue samples collected in 2014, all but 2 samples showed mercury <br /> concentrations less than 0.10 ppm. Two samples of spotted bass showed mercury levels at 0.11 <br /> ppm and 0.13 ppm. Both reservoirs showed a decrease in mercury tissue concentrations over <br /> time. <br /> In a 1993 U.S. Geological Survey (USGS) study, 95 percent(19 of 20) of the samples that were <br /> analyzed for dissolved and total-recoverable mercury had concentrations that were less than the <br /> reporting limit(0.1 µg/L) (USGS 1993). Based on these results, arsenic, chromium, mercury, <br /> nickel, and selenium do not occur in large enough concentrations to pose a concern for the <br /> quality of water in the upper Arkansas River. <br /> Continued rapid development is expected along Colorado's eastern slope as the human <br /> population continues to grow. The State of Colorado expects the population of Front Range <br /> counties (including Boulder, Douglas, El Paso, Jefferson, Larimer, and Weld)to increase by <br /> 1.5 million people by 2035 (Colorado Demography Office 2008). The Arkansas and South Platte <br /> river drainages are the main sources of water for the eastern slope. In theory, demand for water <br /> within the range of greenback cutthroat trout habitat is expected to increase commensurate with <br /> population growth. Potential water diversions or depletions can reduce stream flow; fragment <br /> July 2017 <br /> 15 <br />