2022-11-28-minutes-public-works-study-session

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Finding of No Significant Impact Reclamation is prepared to have up to four 6- to 12 -hour conduit outages for installing the new elements of the outlet works. During these outages, Reclamation would plan to maintain at least 10 cubic feet per second (cfs) of minimum flows in the Kachess River. Reclamation would do this either by relying on passing water over the spillway or by pumping water into the river when the reservoir is above 2,245 feet, which occurs for most of the time in most water years. To increase the likelihood of providing 10 cfs to the Kachess River during the four conduit outages via the methods listed above, Reclamation would rely on the following strategies: • Time outages to coincide with times when the spillway can provide water • Provide incentives to the contractor to limit the duration and/or frequency of outages • Secure the necessary materials before 2024 to facilitate rapid installation while eliminating the potential for schedule impacts from availability or shipping issues • Communicate with the NMFS and USFWS early and often about reservoir and water year predictions In addition, if Reclamation's plan to employ pumps to maintain minimum flows when passing water over the spillway is not possible, Reclamation would employ pumps in the following fashion: • Place pumps in the intake of the spillway or on the dam crest. • Maintain pumps to ensure risks are not imposed on the reservoir and the dam. • Propose to use two pumps with a capacity of 5 cfs each. Reclamation would require redundancy to limit any risk associated with pump outages and shutdowns. With redundancy, there would be an estimated four pumps (two primary and two backup pumps). • Include NMFS-compliant fish screens with the pumps. • Place intake lines in a way to limit effects on the dam face and reservoir bed. If Reclamation is not able to either pass water over the spillway or pump during one of the four possible conduit outages, no flow from the reservoir would be released for up to 6 to 12 hours during that period; however, seepage from the dam and groundwater recharge would continue. In such a potential event, Reclamation estimates that stopping releases from the reservoir (at 30 cfs) for 6 to 12 hours would result in Kachess Reservoir holding approximately 30 acre-feet of water. This could result in a temporary increase in the reservoir's elevation by approximately 0.005 inches in one such event. This change in water level is outside the accuracy of water surface elevation instruments. If necessary, the Keechelus Reservoir would be used to compensate for water deliveries; accordingly, Keechelus Reservoir would have to release an extra 30 acre-feet of water, which would lower the reservoir level by approximately 0.005 inches. During a conduit outage without supplementing water via the spillway or pumping, the construction contractor would adhere to a dewatering plan. A draft plan is provided in Appendix C of the biological assessment (BA). Reclamation will finalize the plan in coordination with the USFWS, NMFS, and other state agencies closer to the actual event, when water levels can be forecasted. Information regarding fish handling and removal is also provided in the dewatering plan and discussed under Conservation Measures and Analysis in the NMFS's Endangered Species Act Kachess Safety of Dams Final Environmental Assessment