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discussion regarding nonnative species in the Colorado pikeminnow Status of the Species and <br /> Baseline sections above, as this threat is similar for all endangered fish in the upper Colorado <br /> River basin, particularly regarding predation from nonnative predators. <br /> 3.2.4 Bonytail <br /> As stated in the Status of the Species section,wild bonytail are so rare that it is currently not <br /> possible to conduct population estimates. However,the Recovery Program is implementing a <br /> stocking program to reestablish populations in the Upper Basin. Limited stocking of bonytail <br /> has begun recently in the Yampa River and White River(in Utah). <br /> The current and increasingly most significant threat to the bonytail in the action area is from <br /> nonnative species,which is discussed in the Status of the Species section. See also the <br /> discussion regarding nonnative species in the Colorado pikeminnow Status of the Species and <br /> Baseline sections above, as this threat is similar for all endangered fish in the upper Colorado <br /> River basin, particularly regarding predation from nonnative predators. <br /> 3.3 Contaminants In The Action Area <br /> 3.3.1 Mercury <br /> An analysis of mercury deposition and its effects on endangered fish in the San Juan River was <br /> recently completed for the Four Corners Power Plant(EPRI 2014). Over 1000 times more coal <br /> was involved in the modeling for that effort than under consultation here, but the mechanics of <br /> mercury emissions and deposition analyzed there are informative for this consultation. <br /> Numerous activities,natural sources, and legacy sources have emitted mercury in the past, and, <br /> given that mercury is a global pollutant,we can assume an unknown quantity of that mercury has <br /> been deposited in the action area over time. Since the surface area of water is low in the Yampa <br /> and White River Basins compared with land area, almost all mercury deposition falls on land, <br /> primarily as elemental or ionic mercury. The deposited mercury either evades back to the <br /> atmosphere or sequesters to soil. Over time,when overland flow takes place, soil is eroded from <br /> the catchment surface and carries adsorbed mercury (e.g., mercury ions; EPRI 2014)with it to <br /> the river. A very small portion (about 0.1 percent in the San Juan River, EPRI 2014) of ionic <br /> mercury deposited in the watershed enters surface waters. Because of the relatively large <br /> amount of past mercury deposited to the soils in a watershed from local, regional and global <br /> sources, mercury in water and fish are slow to respond to changes in mercury deposition, <br /> including reductions in the deposition of mercury (EPRI 2014). Thus, due to the time it takes for <br /> mercury to cycle through the environment, mercury emission and deposition in the action area <br /> that may have occurred in the past may continue to affect the listed species and critical habitats <br /> today and into the future, and yet are considered part of the environmental baseline. <br /> Water mercury concentrations in the Yampa and White Rivers,which includes all critical <br /> habitats in the action area, have not been measured within endangered fish critical habitat in over <br /> a decade. Older measurements were made at imprecise detection levels. Water mercury <br /> concentrations were tested in the White River above Kinney Reservoir(formed by Taylor Draw <br /> Dam) from 1990-1993 (USGS 2015). This reach of the White River is within the action area, as <br /> is all of the White River below Rio Blanco Lake,which marks the upper limit of critical habitat <br /> 38 <br />