You are here

The Importance of Improving Delta Levees

May and June 2012

Levees Crucial to Public Safety, Ecosystem Restoration and Water Supply Reliability

The levees in California’s expansive Delta are vulnerable to damage from flooding, earthquakes and sea-level rise. This precarious situation is a threat to public safety, as well as to the Delta’s ecosystem, its economy and its ability to provide a safe and secure water supply.

The Delta Stewardship Council (Council) is keenly interested in the condition of the 1,100 miles of levees that protect the Delta’s 93 interconnected islands because two-thirds of California’s residents rely on fresh water pumped from the Delta – a failure would no doubt flood hundreds of acres across the north, but it could also compromise drinking water for the entire state.

The California Department of Water Resources (DWR) recently updated the Council on its assessment of Delta levee conditions and the current approximate levels of flood protection for each Delta island.

According to Dave Mraz of DWR’s Delta Levees Program, the majority of the islands are at the minimum level of flood protection, known as the Hazard Mitigation Plan (HMP). Conformance with the HMP standard ensures state and local costs for responding to floods or other emergencies are eligible for reimbursement by the Federal Emergency Management Agency.

Approximately 20 percent of the Delta’s islands have a slightly higher level of flood protection than the HMP, in alignment with the federal government’s Flood Control and Coastal Emergency Act known as PL 84-99. These levees are eligible for additional assistance from the U.S. Army Corp of Engineers should they suffer damage in a flood.

DWR staff reports that they are continually working with local reclamation districts to repair and upgrade the levees in the Delta. They take into account different types of infrastructure, including highways, water systems, and other state assets, and work in cooperation with local reclamation districts to determine where and when to make improvements. The projects are cost-shared by the reclamation districts and the state.

The Delta Protection Commission released an Economic Sustainability Plan in January 2012, which recommends strengthening and widening levees beyond the PL 84-99 standards. The Economic Sustainability Plan also recommends a system-wide approach based on a levee’s importance to the Delta water system as a whole rather than ranking the islands by values or assets.

To view a map of levees in the Delta compliant with PL 84-99, click here.

To view a map of levees compliant with the Hazard Mitigation Plan (HMP), click here.

To view maps of the 93 individual islands in the Delta, click here.

Coequal goals

The Delta Stewardship Council was created in legislation to achieve the state mandated coequal goals for the Delta. "'Coequal goals' means the two goals of providing a more reliable water supply for California and protecting, restoring, and enhancing the Delta ecosystem. The coequal goals shall be achieved in a manner that protects and enhances the unique cultural, recreational, natural resource, and agricultural values of the Delta as an evolving place." (CA Water Code §85054)