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Evaluation draining of the stilling basins <br />The next step consisted of again draining and sampling the outlet and spillway basins, <br />this time after the irrigation season (outlet works) or after a spill (spillway). The outlet basin was <br />drained following the irrigation season in 2002 and 2004. In 2002, evaluation draining of the <br />outlet basin began on 3 December. Sampling was completed on 6 December. All fish were <br />removed using a seine. In 2004, the evaluation draining of the outlet basin began on I November <br />and was completed on 3 November. <br />The spillway basin was sampled following spills in 2002 and 2005. In 2002, pumping of <br />the spillway basin began on 22 October and was completed on 15 November. The spillway basin <br />evaluation draining in 2002 was thought to be successful at removing fish remaining from the <br />initial sampling in the spring and thus served to clear the spillway basin for the next spill (which <br />did not occur unti12005). The spillway basin was sampled after draining using both <br />electrofishing and gill nets. No spill occurred in 2004, thus only an initial sampling occurred <br />during that year. <br />In 2005, the spillway basin was pumped for three weeks in September to allow an <br />evaluation of fish escapement over the spillway. Toward the end of the pumping period, river <br />flows were increased to aid sampling efforts in the lower Duchesne River. Though the releases <br />from the outlet into the spillway channel approximately 900 feet downstream of the spillway <br />basin, the backflow was large enough to completely refill the spillway basin. It then became <br />necessary to evaluate escapement using other methods in the stilling basin. Gill nets, fyke nets, <br />and electrofishing were employed in an effort to sample and collect as many fish as possible and <br />evaluate escapement. All walleye and smallmouth bass collected in both the stilling basins were <br />lethally removed. <br />7 <br />