ABOUT
Whittier Narrows Dam is a Dam Safety Action Classification (DSAC) 1 project, which is defined by ER 1110-2-1156 as "Very High Urgency" where the combination of life or economic consequences with probability of failure is very high with over 1 million people and $204 billion in economic development at risk. The project will address two dam safety issues: foundation seepage with backward erosion piping at the west and central embankments; and overtopping.
The Whittier Narrows Dam Safety Modification Project is a flood control project with incidental water conservation. This project is the central element of the Los Angeles County Drainage Area (LACDA) flood control system. The dam was constructed in 1957 and is operated by the U.S. Army Corps of Engineers, Los Angeles District. The project is located at the "Whittier Narrows", a natural gap in the hills that form the southern boundary of the San Gabriel Valley. The Rio Hondo and the San Gabriel River flow through the reservoir flood control basin.
KEY CONSIDERATIONS
Whittier Narrows provides flood risk management to 1.25 million residents in the greater Los Angeles area and is designated as a Dam Safety Action Classification (DSAC) 1 (urgent and compelling) project.
Dam safety modifications were recommended in June 2019 to reduce the overall risk of failure, potential loss of life, economic consequences, and environmental effects.
The U.S. Army Corps of Engineers awarded the Whittier Narrows Dam Safety Modification Integrated Design and Construction Base Contract in May 2025. The base contract includes preconstruction services and early work items. Congress appropriated $571 million in Fiscal Year 2026 (General Construction Funding) that will fully fund the construction option to the ceiling price and provide construction management and oversight funding through FY27. To date, design has advanced to 95% maturity and advanced extensive real estate efforts, which includes early coordination associated with the relocation of two major roads and over 50 utilities. In total, there are 9 compensable and 48 non-compensable utilities requiring relocation.
ORIGINAL AUTHORIZATION: The Whittiers Narrow Dam was authorized by Public Law 77-228, "Flood Control Act of 1941".
ACTIVITIES FOR FISCAL YEAR 2026: President Donald Trump signed the Interior and Environmental Appropriations Act, January 23, 2026, which authorized incremental funding for the project. The construction contract is scheduled for March 2026 award. The first increment will utilize the Incremental Funding Clause. The current working estimate for the project is $1.367 billion for (Construction General) for dam safety.
The FY2026 Interior and Environmental Appropriations Act provided authority to utilize incremental contract funding, this will allow the project to award the construction option with funds on hand. The Fiscal Year 2026 President’s Budget included $571 million, to fully fund the construction contract. An Integrated Design and Construction (IDAC) contract was advertised in January 2024. Awarded Preconstruction Services April 25, 2025. Delayed from October 2024 due to extensive negotiations.
