1 Delta Risk Management Strategy Delta-Suisun Marsh Branch Department of Water Resources SCWC/SCWD MEETING JUNE 27, 2007

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3 DRMS Development of DRMS 2000 CALFED ROD Called for Risk Assessment of Delta Levees 2005 – Levee Risk Analysis Team – Did Preliminary Work – Seismic only – Also Developed Project Scope for DRMS 2005 – AB 1200 Enacted Governor’s Executive Order- Delta Vision

4 DRMS - AB 1200 (CWC 139.2) Sets General Framework for DRSM -DWR Shall Evaluate Potential Impacts on 50, 100, 200-year projections on possible impacts to Delta from: -Subsidence - Earthquakes - Floods - Climate Change - & Combination of above

5 DRMS AB 1200 Continued (CWC 139.4) –DWR/DFG to Determine Principal Options for Delta – DWR to comparatively rate for ability to: Prevent Disruption of Water Supplies Derived from Delta Improve the Quality of Water Supplies Derived from Delta Reduce Salts, Maintain Water Quality Preserve, Protect, Improve Delta Levees Protect Water Rights/Environments of River Systems Protect Infrastructure within Delta –DFG shall rate all options for its ability to restore salmon & other fisheries that use the Delta –Report Due – January 2008

6 DRMS Contract Information –URS Corporation, Oakland, CA Over 20 subcontractors –Approved by DGS - March 6, year contract Includes a new LiDAR aerial survey of Delta Guidance to URS – No new studies, use best available info, however, some limited exclusions: –Subsidence; Seismic hazard –DRMS report has several new models of Delta operations (i.e., Risk, Hydrodynamics, ER&R, Water Analysis)

7 DRMS DRMS Technical Memoranda Risk Analysis Seismology (PSHA) Ecological Impacts (Ecosystem) Subsidence Levee Vulnerability Flood Hazard Wind Wave Analysis Climate Change Water Analysis Module (Hydrodynamics) Geomorphology Impact to Infrastructure Economic Consequences Emergency Response & Repair

8 DRMS Phase 1 Based on Business-As-Usual Assumptions Development of a Risk Analysis to Evaluate the Impact to Delta Levees from: –Floods –Earthquakes –Subsidence –Normal Conditions –Climate Change Determine Consequences to Economy & Eco-System based on Risks Found Draft Risk Analysis Report submitted April 23 ’07 –Public Draft July 2007 –Independent Review by CALFED – July – August ‘07

9 Summary of Key Findings from Phase 1 (preliminary) flood-related island failures expected in the next 100 years simultaneous island failures in a major flood event % chance of 30+ islands failing simultaneously in a major earthquake in the next 25 years

10 Summary of Key Findings (continued) Probability of flood-related levee failure –increases by 10% in 2050 –Increases by 20% in 2100 Probability of seismic-related levee failure –increases by 12% in 2050 –increases by 27% in feet of sea level rise would push the salt line about 3 miles to the east

11 DRMS Phase 2 Development of Risk Reduction/Risk Management Strategies for Long-Term Management of Delta –Draft Final Report Due August ’07 –Public Review Draft – Oct ’07 –Independent Review by CALFED – Oct – Nov ’07 –DRMS Final Report – November 2007 Includes Recommendations for Future Work/Studies in the Delta Will be provided to Delta Vision Blue Ribbon Task Force for Consideration in the “Vision for the Delta”

12 Delta Risk Management Strategy Phase 2: Development and Evaluation of Risk Reduction Strategies Develop a menu of risk reduction measures that could reduce risk – “building blocks” Package the measures into different combinations -> “trial scenarios” Use Risk Model to evaluate potential risk reductions Evaluate benefits and costs of risk reduction measures

13 Potential Risk Reduction Building Blocks: Improved Levee Maintenance Upgraded Delta & Urban Levees Enhanced Emergency Preparedness/Response Pre-Flooding of Selected Western Islands Land Use Changes to Reduce Subsidence Armored Through Delta “Pathway” Conveyance Isolated Conveyance Elevation of State Highways on Piers Armored Infrastructure Corridor San Joaquin By-Pass Suisun Marsh Restoration Cache Slough Restoration Fish Screens Reduced Water Exports Delta Risk Management Strategy

14 DRMS Phase 2 Trial Scenarios Being Proposed Improved Levees Armored Pathway Isolated Conveyance

15 Thank You For more information on the DMRS work, please see the DRMS web site at: