Laserfiche WebLink
c. Altered ovarian morphology, delayed oocyte development; <br /> d. Reduced reproductive success; <br /> e. Transfer of dietary Hg of the maternal adult during oogenesis and into the developing <br /> embryo. <br /> 3. Inability to grow new brain cells or significantly reduce brain mercury. <br /> Mercury contamination is a widespread problem across the United States. Nearly half of all <br /> lakes and reservoirs in the country are above the human health screening value for mercury(EPA <br /> 2009). The vast majority (97 percent) of health advisories issued by the EPA for the <br /> consumption of fish from lakes and reservoirs in 2008 were due to mercury, PCBs, dioxins and <br /> furans, DDT, and chlordane. Of these contaminants,mercury was by far the most commonly <br /> detected. Of the predacious fish sampled (as opposed to bottom-dwellers), 48.8 percent of the <br /> sampled population of lakes across the country had mercury tissue concentrations that exceeded <br /> the 0.3 micrograms per gram (parts per million)human health screening value for mercury, <br /> which represented a total of 36,422 lakes (EPA 2009). <br /> 4.3.3.1 Colorado pikeminnow <br /> Of the four endangered fish in the Yampa and White Rivers,we expect the Colorado <br /> pikeminnow to be at greatest risk from exposure to mercury that has been deposited within the <br /> Yampa and White rivers from project-related emissions from the Craig Generating Station. This <br /> is due to two factors. First, Colorado pikeminnow have a higher likelihood of bioaccumulating <br /> mercury. Predatory organisms at the top of the food web generally have higher mercury <br /> concentrations in their bodies because mercury tends to biomagnify up through the food chain <br /> and concentrate in upper trophic levels (EPA 1997). Unlike the other three endangered fish, the <br /> Colorado pikeminnow is a top predator and is almost entirely piscivorous once it grows to be <br /> 80-100 mm (3 to 4 inches) long (Vanicek and Kramer 1969). The Colorado pikeminnow is also <br /> a long-lived fish, living 55 years or more (Osmundson et al. 1997). Thus,mercury will <br /> accumulate more rapidly and over a longer time period than in the other three endangered fish <br /> species. <br /> Second, Colorado pikeminnow occupy habitats closer to the Craig Generating Station than the <br /> other endangered fish and would, therefore,be exposed to the highest concentrations of mercury <br /> resulting from the project. Critical habitats designated for each endangered fish were based on <br /> areas of known occupancy. Only critical habitat designated for the Colorado pikeminnow is <br /> found within the airshed identified for analysis, centered around the Craig Generating Station. <br /> The other three endangered fish and their critical habitats are found lower down in and along the <br /> Yampa River(razorback sucker, humpback chub, bonytail), and lower down in and along the <br /> White River(razorback sucker). We expect the contribution of mercury from the Craig <br /> Generating Station in the Yampa and White Rivers to diminish with distance from that point <br /> source through dilution (from additional water entering from tributaries) and removal (through <br /> biological uptake and potential adsorption to sediments). <br /> Beckvar et al. (2005) suggested a threshold-effect level of< 0.2 micrograms per gram (µg/g)wet <br /> weight(WW)mercury in whole body fish as being generally protective of juvenile and adult <br /> fish; concentrations below this level would not result in a�detectible effects to these fish. To <br /> 49 <br />