75E - PH - WATER MANAGEMENT PLAN

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2015 URBAN WATER MANAGEMENT PLAN levees and island flooding could affect Delta water quality and SWP operations for several months. When islands are flooded, DWR may need to drastically decrease or even cease SWP Delta exports to evaluate damage caused by salinity in the Delta. The Delta Risk Management Strategy addresses the problem of Delta levee failure and evaluates alternatives to reduce the risk to the Delta. Four scenarios were developed to represent a range of possible risk reduction strategies (Department of Water Resources, The State Water Project Final Delivery Capability Report 2015, July 2015). They are: • Trial Scenario 1 Improved Levees: This scenario looks at improving the reliability of Delta levees against flood- induced failures by providing up to 100 -year flood protection. The report found that improved levees would not reduce the risk of potential water export interruptions, nor would it change the seismic risk of most levees. • Trial Scenario 2 Armored Pathway: This scenario looks at improving the reliability of water conveyance by creating a route through the Delta that has high reliability and the ability to minimize saltwater intrusion into the south Delta. The report found that this scenario would have the joint benefit of reducing the likelihood of levee failures from flood events and earthquakes, and of significantly reducing the likelihood of export disruptions. • Trial Scenario 3 Isolated Conveyance: This scenario looks to provide high reliability for conveyance of export water by building an isolated conveyance facility on the east side of the Delta. The effects of this scenario are similar to those for Trial Scenario 2sbut with the added consequence of seismic risk of levee failure on islands that are not part of the isolated conveyance facility. • Trial Scenario 4 Dual Conveyance: This scenario is a combination of Scenarios 2 and 3 as it looks to improve reliability and flexibility for conveyance; of export water by constructing an isolated conveyance facility and through -Delta conveyance. It would mitigate the vulnerability of water exports associated with Delta levee failure and offer flexibility in water exports from the Delta and the isolated conveyance facility. However, seismic risk would not reduced on islands not part of the export conveyance system or infrastructure pathway. DWR has altered the SWP operations to accommodate species of fish listed under the Biops, and these changes have adversely Impacted SWP deliveries. DWR's Water Allocation Analysis indicated that export restrictions are currently reducing deliveries to Metropolitan as much as 150 TAF to 200 TAF under median hydrologic conditions. Operational constraints likely will continue until a long -term solution to the problems in the Bay -Delta is identified and implemented. New biological opinions for listed species under the Federal ESA or by the California Department of Fish and Game's issuance of incidental take authorizations under the Federal ESA and California ESA might further adversely affect SWP and CVP operations. Additionally, new litigation, listings of additional species or new regulatory requirements could further adversely affect SWP operations in the future by requiring additional export reductions, releases of additional water from storage or other operational changes impacting water supply operations. 75E -41 amadis.com 3 -7