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4.3.2.4 Bonytail <br /> We have no data on past or current selenium fish tissue levels in bonytail in the Yampa or White <br /> Rivers. However, water selenium concentrations in these two rivers are generally below the <br /> chronic standard. Bonytail have only recently been stocked into the lower Yampa and White <br /> Rivers. We have no data indicating that there is immediate cause for alarm, although further <br /> sampling and testing for selenium is warranted. <br /> As stated above,we believe nonnative species are the primary limiting factor for bonytail <br /> numbers, successful recruitment, and their distribution within the action area. While further <br /> sampling and testing for selenium is warranted,we do not see any evidence indicating that <br /> potential effects from selenium rise to the level of reducing population numbers, are limiting <br /> reproduction, or are constraining bonytail distribution. <br /> 4.3 Effects to Critical Habitat <br /> In addition to impacts to individual Colorado River fish, impacts would also potentially occur to <br /> those species' designated critical habitats in the action area. The PCEs of critical habitat for all <br /> four endangered fish are identical and contain the following (50 CFR 13378): <br /> 1. Water: This includes a quantity of water of sufficient quality (i.e. temperature, dissolved <br /> oxygen, lack of contaminants,nutrients,turbidity, etc.)that is delivered to a specific <br /> location in accordance with a hydrologic regime that is required for the particular life <br /> stage for each species; <br /> 2. Physical Habitat: This includes areas of the Colorado River system that are inhabited or <br /> potentially habitable by fish for use in spawning, nursery, feeding, and rearing, or <br /> corridors between these areas. In addition to river channels,these areas also include <br /> bottom lands, side channel, secondary channels, oxbows,backwaters, and other areas in <br /> the 100-year floodplain, which when inundated provide spawning,nursery, feeding and <br /> rearing habitats, or access to these habitats; <br /> 3. Biological Environment: Food supply, predation, and competition are important elements <br /> of the biological environment and are considered components of this constituent element. <br /> Food supply is a function of nutrient supply,productivity, and availability to each life <br /> stage of the species. Predation and competition, although considered normal components <br /> of this environment, can be out of balance due to introduced nonnative fish species. <br /> 4.3.1 Colorado pikeminnow <br /> Mercury from the combustion of Trapper coal at the Craig Generating Station that is deposited <br /> either directly or indirectly into the designated critical habitat for this species would have the <br /> potential to adversely impact its critical habitat. As stated in the Baseline section above, critical <br /> habitat for the Colorado pikeminnow occurs within the mercury deposition zone of analysis for <br /> this project. An increase in the amount of mercury in river water negatively impacts water <br /> quality (PCE 91). It is difficult to quantify the level of impact from the proposed actions to <br /> critical habitat given the lack of information on where the mercury in the analysis area originates <br /> from. However, if it assumed that only five percent of the mercury deposited into the analysis <br /> 56 <br />