DWR Announces Partnership to Develop Alluvial Fan Task Force

California’s Department of Water Resources (DWR) will partner with California State University, San Bernardino’s (CSUSB) Water Resources Institute to develop an Alluvial Fan Task Force.

The proposed task force will address issues related to unique flood hazards associated with the rapid rate of housing development on alluvial fans. An alluvial fan is a fan-shaped deposit formed where fast flowing water flattens, slows and spreads—typically at the exit of a canyon or mountain pass onto a flatter plain. Principal hazards associated with alluvial fan flooding are high-velocity, debris-laden flows resulting from a series of storms, particularly following wildfires in semi-arid regions.

Alluvial fans are prevalent throughout Southern California and are most common in San Bernardino, Riverside, Los Angeles, Ventura, Santa Barbara, San Luis Obispo, Kern, Orange, Imperial and San Diego counties.

DWR Director Lester Snow is expected to make appointments to the task force in coming months. Broad representation is expected from local communities to include developers, elected officials, flood control district members, storm water managers, water suppliers, water quality regulators, Native Americans and the environmental community.

Members of the task force will be charged with reviewing alluvial fan flood history to develop a model ordinance that will reduce long-term flood damages, and with creating land use guidelines for development on alluvial fans. The ordinance will be developed collaboratively by members of the proposed task force under the guidance of a professional facilitator. Findings of the proposed Alluvial Fan Task Force will be reported to the legislature.

DWR will utilize the knowledge and expertise of the CSUSB Water Resources Institute to coordinate task force activities. Seven plenary meetings are planned in communities most affected by rapid growth on alluvial fans as projected by local governments through 2030.

The Federal Emergency Management Agency is funding the task force under the Pre-Mitigation Disaster Planning Grant Program.

The Department of Water Resources operates and maintains the State Water Project, provides dam safety and flood control and inspection services, assists local water districts in water management and water conservation planning, and plans for future statewide water needs.

Source: DWR Public Affairs Office