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area is generated locally, the impact directly from the proposed action may be relatively small. <br /> Nevertheless,when added to the other regional and global sources of mercury being deposited <br /> into the action area and the mercury already within the system, additional mercury from the <br /> proposed action is likely to result in an adverse impact to critical habitat through a reduction in <br /> water quality. <br /> Although potentially smaller than mercury, impacts to critical habitat from selenium added to the <br /> system through coal combustion, together with selenium added to the system by other sources, <br /> may also result adverse impacts to critical habitat for the endangered fish. However, current <br /> water quality data from the Yampa and White Rivers indicate that selenium levels have not <br /> exceeded the chronic aquatic life standard, and are likely to have less of an impact on water <br /> quality in critical habitat than mercury. <br /> The Yampa and White Rivers are not currently listed as impaired for either mercury or selenium <br /> on the EPA 303(d) list(CDPHE 20102b). However,mercury concentrations have not been <br /> tested as recently as selenium and have exceeded the chronic aquatic life standard at given water <br /> quality monitoring stations along both the Yampa and White Rivers in the past. <br /> Considering together the contributions of mercury and selenium from the project to the Yampa <br /> and White Rivers in the context of existing water quality data, the weight of evidence indicates <br /> that PCE 91 in Colorado pikeminnow critical habitat would be adversely affected through a <br /> reduction in water quality, but is not and would not be compromised to a point that it no longer <br /> provides water of sufficient quality essential for the conservation of the species. <br /> As discussed in the Status of the Species and Baseline sections above, endangered fish physical <br /> habitat(PCE#2) and the biological environment(PCE#3) are currently experiencing the most <br /> severe impacts,which are unrelated to the project and unaffected by the project(e.g., dams and <br /> diversions impacting PCE#2,nonnative species impacting PCE#3). <br /> 4.3.2 Razorback sucker <br /> Razorback sucker critical habitat would be affected in a similar way by the project that Colorado <br /> pikeminnow critical habitat would be, as described above, although we expect the impacts to be <br /> of a lesser magnitude. Razorback sucker critical habitat does not extend as far up the Yampa or <br /> White Rivers and is, therefore, further from the point source of the Craig Generating Station. <br /> Razorback sucker critical habitat is located downstream from, but not within, the mercury <br /> deposition airshed analyzed for this consultation. Mercury and selenium contributions from the <br /> project to the action area diminish with distance from this point source. This increases our <br /> confidence that the project would not diminish water quality to a point where critical habitat can <br /> no longer provide the PCEs essential for the conservation of the species. <br /> 57 <br />