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<br />Jon Nelson lowers a 12-inch in diameter Secchi <br />disk painted with two black and two white <br />alternating quadrants to measure and record the <br />turbidity or water quality at survey sites in the <br />Colorado River. Clear water is one indicator of <br />mussel presence. LCR photo by Steve Leon <br /> <br />in the plan, Regional staff members, under the direction of <br />Leonard Willett, Hoover Dam's Water Treatment manager, <br />are, "Currently setting up monitoring programs at all three <br />dams - Hoover, Davis and Parker," he said. As part of LCD <br />Monitoring, plates have been installed in the dams' forebays <br />and tail races. "Bio-Boxes" (side-stream samplers, which are <br />aquarium-like devices to monitor the settlement of mussels in <br />the powerplant) have also been installed. <br />The plan is based on a recently completed comprehensive <br />L- review of all three dams with a quagga mussel consultant - <br />RNT Consulting, Inc. - and addresses methods for dealing <br />'I with and controlling quagga mussels. <br />"At individual dams, the mitigation strategy chosen will <br />. be based on engineering assessment of the individual <br />... mitigation strategies available," it said. <br />"Duplex strainer screens will be replaced with self- <br />cleaning lI8-inch screens to collect and block adult shells <br />from entering the system,"Willet added, "as we move forward <br />in the fight against quaggas." <br />He also said the plan was also presented recently to the <br />power customers and as well as Reclamation personnel. <br />Concurrently, an ongoing monitoring program will <br />determine what type of control system to set up or if any <br />system is needed, Willett said. <br />The consultant's findings and recommendations were divided <br />into two reports, one that focuses on Davis and Parker Dams - <br />"Assessment of the Potential Impact of Quagga Mussels on Davis <br />and Parker Dam and Recommendations for Monitoring and <br />Control." The <br />second report, which focuses on Hoover Dam, will appear later this <br />month. <br />"Hoover and Davis dams appear to have time to evaluate <br />monitoring data and determine what path forward we want to <br />choose," said Willett. <br />Communication with all the utilities will continue as alternatives <br />are determined and then the associated costs will be presented for <br />their consideration. <br />"Parker Dam staff on the other hand have started implementing a <br />Rapid Response control action because mussels have been detected <br />in the cooling water systems," said Willett. "The response consists of <br />a thermal treatment where they run hot water through the cooling <br />lines when the generator is not running. Long term solutions are <br />being evaluated but it will take a year or two for them to be designed <br />and implemented. This month I will be evaluating a 40-micron filter <br />in Pennsylvania for proper design and possible future usage at the <br />Dams." <br />Additionally, Regional staff members check the river <br />downstream from Hoover Dam the second week of each month in <br />day-long series of water sample collections, record keeping, and <br />clarity monitoring. <br /> <br />