Title
Consider receiving a presentation on the Nacimiento Dam and San Antonio Dam Spillway Condition Assessment. (ADDED VIA ADDENDA)
Report
RECOMMENDATION:
It is recommended that the Monterey County Water Resources Agency Board of Supervisors:
Receive a presentation on the Nacimiento Dam and San Antonio Dam Spillway Condition Assessment.
SUMMARY:
This presentation will provide a description of Nacimiento and San Antonio Dam hazard classification, construction and operational history of both spillways, spillway condition assessment report conclusions and recommendations, and spillway work planned for the present fiscal year.
DISCUSSION:
Monterey County Water Resources Agency (MCWRA) owns and operates Nacimiento and San Antonio Dams. Nacimiento Dam is regulated with regard to dam safety matters by California Department of Water Resources, Division of Safety of Dams (DSOD), and the Federal Energy Regulatory Commission (FERC) because a hydroelectric plant is located at the dam. San Antonio Dam is regulated with regard to dam safety matters by DSOD. Based on downstream potential for loss of life and infrastructure in the event of dam failure, DSOD classifies Nacimiento and San Antonio Dams as "Extremely High Hazard" and FERC classifies Nacimiento Dam as "High Hazard." DSOD and FERC have authority to restrict water storage at regulated dams if unsafe conditions occur.
After the 2017 Oroville Dam spillway incident, DSOD and FERC directed all high hazard (and higher) classification dam owners to complete focused spillway inspections and condition assessment reports. MCWRA hired GEI Consultants, Inc., a firm with extensive dam sector experience, to inspect and prepare condition assessment reports for both spillways. Inspections were completed in July 2017. The condition assessment report for San Antonio Dam spillway was completed in May 2018 and submitted to DSOD on May 23, 2018. The condition assessment report for Nacimiento Dam spillway was completed in ...
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