County Also Requests Congress Consider Transfer of Authority of Army Corps Flood Channels

Constructed in 1957 in the southern stretches of the San Gabriel Valley, the Whittier Narrows Dam no longer meets tolerable-risk guidelines set by the U.S. Army Corps of Engineers (USACE) and requires immediate upgrades and repairs. The U.S. Army Corps has ranked the retrofitting of the Whittier Narrows Dam as its highest national priority, estimating the cost to repair and upgrade the structure at hundreds of millions of dollars. Urging the federal government to begin swift repairs, today the Board of Supervisors approved a motion, authored by Los Angeles County Supervisor Hilda L. Solis, that will request that the U.S. Congress immediately allocate funds to expedite needed upgrades and ensure the safety of millions of residents throughout Los Angeles County.

“The rehabilitation of the Whittier Narrows Dam is a high priority because of the significant loss of life and high economic impacts that hang in the balance. Millions of LA County residents live downstream of the dam, and we cannot afford to wait to begin these upgrades,” said Supervisor Solis. “In the event of significant rainfall, the Whittier Narrows Dam could erode and give way, resulting in a catastrophic disaster. I spoke with Members of Congress about the importance of the Whittier Narrows Dam while in Washington D.C. earlier this year because I and my constituents demand action. I am pleased the Army Corps has ranked this project on the top of its national priority list because that will enable the Corps to access the funds needed to quickly begin repairs.”

Though the Army Corps built the 60-year-old Whittier Narrows structure, due to budget cuts, over the years the Army Corps has struggled to properly maintain the dam. Recently, federal engineers have noted that the dam could fail if a storm delivered more water than the dam could store or if seepage eroded the soft soil underneath the structure. In addition, federal engineers have said that heavy rains could trigger a premature opening of the dam’s massive spillway on the San Gabriel River, releasing more than 20 times what the downstream channel could safely contain within its levees.

Stretching from Montebello to Pico Rivera, the dam crosses both the San Gabriel and Rio Hondo rivers. The structure is one of several flood control facilities under the Army Corps’ jurisdiction. The Corps needs up to $600 million in federal funding to repair the aging 3-mile-long dam.

In September 2015, the Board of Supervisors authorized the LA County Department of Public Works to collaborate with the Corps to work on a Water Conservation and Supply Feasibility Study on the dam. In May 2016, the Whittier Narrows Dam was designated as “very high risk” structure. 

In September 2017, the Board approved a motion by Supervisor Solis to send a five-signature letter to the U.S. Department of the Interior and the LA County Congressional Delegation requesting that the Assistant Secretary to the Army Corps provide a report on the status of the Dam Safety Study, a timeline for any proposed repairs to the dam, and efforts to coordinate emergency managers. The motion also directed Public Works, in coordination with the Office of Emergency Management, to report back on the County’s efforts to coordinate with the Corps and downstream communities to ensure local measures are in place during emergencies.  

As a result, with help from the Corps and downstream communities, the County prepared an emergency response to a possible flood. On December 14, 2018, the Corps issued a Draft Environmental Impact Statement (EIS) for a 45-day public comment period assessing the various alternatives to addressing the deficiencies at the dam. The Water Conservation Study is currently on hold due to the dam’s safety issues and designation of critical habitat for endangered bird species within the dam.

In the event of a dam failure, one of the communities that may be hardest hit would be Pico Rivera, which is located directly below the dam. With a fierce storm, Pico Rivera could be hit with water 20 feet deep, and the adjacent City of Downey could see 15 feet of water. Today’s motion also directs the County Office of Emergency Management, along with LA County Department of Public Works, update the Board in 30 days on the local measures adopted that will ensure the safety of all downstream communities.

In a separate, but affiliated action, the Board of Supervisors today also approved a related Board motion, authored by Supervisor Solis and co-authored by Supervisor Sheila Kuehl, that directs the County’s Chief Executive Officer, in coordination with the Los Angeles County Department of Public Works, to send a five-signature letter to the LA County U.S. Congressional Delegation to request their support for a Disposition Study to explore the transfer of authority of 40-miles of open channels currently under the jurisdiction of the U.S. Army Corps of Engineers over to the Los Angeles County Flood Control District.

Contact: Rosa Maria Santana, Deputy Communications Director, 213-359-0795 or