Laserfiche WebLink
<br />uM~ <br /> <br />-Gravel pits connected to the main channel of the river will <br />provide suitable nursery and/or grow-out habitat for young <br />razorbacks, and habitat for adult razorbacks. <br />-Restoration of the Gravel Pit will not affect fish species <br />composition and relative abundance in the river adjacent to the <br />site. <br />-Site configuration (i.e., making the site drainable) can be <br />used to prevent buildup of nonnative fishes, by allowing the <br />site to fill and drain naturally during spring runoff. <br /> <br />Adobe Creek <br /> <br />Selenium concentrations in the Gunnison River and in the <br />Colorado River below the Gunnison exceed levels of concern. <br />Adobe Creek is a tertiary channel along the Colorado River (RM <br />160). levels of selenium measured in surface and ground water <br />samples from Adobe Creek were 4ppm (level of concern is 2- <br />5ppm); in dry weight whole-body fish samples were 9 to 17ppm <br />(level of concern is 8ppm). Adobe Creek, combined with Walter <br />Walker and Horsethief, will help determine if razorback suckers <br />are adversely affected at floodplain sites with high levels of <br />selenium and, if so, if "freshening flows" can be used to <br />reduce selenium levels. Following are hypotheses to be tested: <br /> <br />-Tertiary channels connected to the main channel of the river <br />will provide suitable nursery and/or grow-out habitat for young <br />razorbacks, and habitat for adult razorbacks. <br />-Contaminant levels (selenium and other inorganics) at Adobe <br />Creek will not adversely affect razorback sucker life history <br />phases. <br />-Ambient concentrations of selenium at Adobe Creek will not <br />adversely affect reproductive success of razorbacks, either <br />directly or via bioaccumulation. <br />-Manipulation of flows through Adobe Creek will reduce selenium <br />concentrations. <br />-Restoration of Adobe Creek will not affect fish species <br />composition and relative abundance in the river adjacent to the <br />site. <br /> <br />Walter Walker <br /> <br />Selenium concentrations in the Gunnison River and in the <br />Colorado River below the Gunnison exceed levels of concern. <br />Walter Walker is a large floodplain depression along the <br />Colorado River (RM 164). levels of selenium measured in water <br />samples from Walter Walker ranged <1 to 170ppm (level of <br />concern is 2-5ppm); levels in dry weight whole-body fish <br />samples ranged 74 to 137ppm (level of concern is 8ppm). Walter <br />Walker, combined with Adobe Creek and Horsethief, will help <br />determine if razorback suckers are adversely affected at <br />floodplain sites with high levels of selenium and, if so, if <br /> <br />14 <br />