County Directs Coordination on Whittier Narrows Dam Project to Address Impacts on Parks and Infrastructure

Solis motion calls for mitigation of effects on trails, open space and transportation during long-term federal upgrades

SAN GABRIEL VALLEY, Calif. — The Los Angeles County Board of Supervisors today approved a motion by Board Chair and 1st District Supervisor Hilda L. Solis directing county departments to coordinate with the U.S. Army Corps of Engineers on mitigation efforts as the Whittier Narrows Dam Safety Modification Project moves forward.

The motion cites potential impacts to parks, trails and surrounding communities during the yearslong construction project.

The Whittier Narrows Dam, operated by the U.S. Army Corps of Engineers, is a key component of the Los Angeles County Drainage Area flood-control system. The agency estimates the dam helps protect approximately 1.25 million residents in 25 downstream communities, including Montebello, Pico Rivera and South El Monte, from flooding along the Rio Hondo and San Gabriel rivers.

Built in 1957, the dam has been identified by the Army Corps as a high-risk structure requiring major rehabilitation. Construction is expected to take five to seven years.

“Whittier Narrows Dam is one of the region’s most critical flood-control systems, but the communities surrounding it also rely on these same lands for recreation, mobility and open space,” said Board Chair and First District Supervisor Hilda L. Solis whose district includes Montebello and South El Monte. “As this project moves forward, the County should work to ensure that safety improvements do not come at the expense of long-term community access and that impacts are minimized and properly mitigated.”

County officials said the project is expected to significantly affect trails, roadways and recreational facilities used by residents throughout the San Gabriel Valley.

“The retrofit of the Whittier Narrows Dam is a regional solution to a regional challenge, but we also have to protect things like park, open space, bike trail connections and key access roads for the communities immediately surrounding the dam. Today’s motion will help us ensure that we work with cities like Pico Rivera and others to protect that access to those critical resources,” said Fourth District Supervisor Janice Hahn, whose district includes Pico Rivera. 

“Pico Rivera residents have a strong connection to the Whittier Narrows Dam, whether for recreation, transportation or access to open space,” said Pico Rivera Mayor Gustavo V. Camacho. “As this federal infrastructure project advances, ongoing communication, multilingual outreach and thoughtful mitigation measures will be essential to helping residents stay informed and connected to the resources they rely on.”

Expected impacts include disruptions to open-space access and potential effects on regional transportation and recreation networks, including the Countywide Bicycle Master Plan, the San Gabriel Valley Greenway Network and the San Gabriel River Bike Path.

The motion directs the County’s Department of Public Works, in coordination with the Department of Parks and Recreation and local jurisdictions, to work with the Army Corps to identify, avoid and mitigate impacts to facilities where feasible and ensure they are restored following construction.

The motion also calls for multilingual outreach to notify residents about construction schedules, detours and recreational closures or restrictions throughout the project.

County departments must report back to the Board of Supervisors within 60 days on coordination efforts with the Army Corps.

In addition, the County Chief Executive Office’s Legislative Affairs and Intergovernmental Relations branch, along with Public Works and Parks and Recreation, will send a five-signature letter to the Army Corps and the County’s congressional delegation outlining concerns about project impacts and requesting enhanced coordination and community outreach.