BOARD AGENDA MEMORANDUM
SUBJECT:
Title
Coyote Creek Flood Risk Reduction Ad Hoc Committee's Recommendations and Associated Staff Analysis from the Committee's October 5, 2017, Meeting.
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RECOMMENDATION:
Recommendation
A. Receive a report from the Coyote Creek Flood Risk Reduction Ad Hoc Committee and staff analysis.
B. Provide direction to staff to operate the Anderson Reservoir system through the winter of 2017/2018 following the 40% exceedance rule curve that was recommended by the Coyote Creek Flood Risk Reduction Ad Hoc Committee at the October 5, 2017 meeting to reduce the risk of flooding along Coyote Creek and provide adequate water supply while balancing other beneficial uses.
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SUMMARY:
On October 5, 2017, the Coyote Creek Flood Risk Reduction Ad Hoc Committee received information and discussed alternatives for providing short-term flood risk reduction on Coyote Creek.
Staff Analysis:
Information on Anderson Dam reservoir operation options for short-term flood risk reduction on Coyote Creek was provided to the Committee on August 31 and October 5, 2017 for discussion. The meeting agendas and supporting materials are attached. Two alternatives were considered; pump over and reduced reservoir storage.
The pump-over option would install a large-scale pumping system using the existing spillway to increase the release of incoming flows into Anderson Reservoir and thereby maintain storage goals. The pump-over option has significant risks, costs, and would require a lengthy environmental review and permitting effort, and is unlikely to be implementable for at least the next four to five winters.
Similar results can be achieved by operating the reservoir at a reduced elevation, meaning at a lower storage level. The reduced reservoir storage would increase the available flood storage volume behind the dam during the winter season.
Both options would reduce the risk of flooding for the downstream communities. If there is a below average...
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