Project Sponsor

Orange County Public Works (OCPW), acting on behalf of the Orange County Flood Control District (OCFCD).

Current Status

The Santiago Creek project was authorized in 1986 as a component of the Santa Ana River Mainstem Flood Control Project (SARMP). An update to the design of the Santiago Creek component was last completed in 1988. All other components of the SARMP have been or are being constructed, except the Santiago Creek component.  Due to the age of the last report, an Engineering Documentation Report (EDR) is being prepared to update the design of the project to current engineering standards and practices. A Supplemental Environmental Assessment (SEA), to satisfy requirements of the National Environmental Policy Act (NEPA) and an Initial Study with Mitigated Negative Declaration (IS/MND), to satisfy requirements of the California Environmental Quality Act, are being prepared to accompany the EDR. The SEA/IS/MND is necessary to document and evaluate the impacts of design refinements on resources and to document changed conditions in the project area since 1988. The SEA/IS/MND is currently undergoing internal review after which it will be released for a 60-day public review and comment period. After the public review and comment period and pending approval of the Final SEA/IS/MND, the next step, if funded, would be the Detailed Design phase, with Construction potentially commencing in 2025.

Project Description and Background

The purpose of the SARMP, including the Santiago Creek component, is to provide flood risk reduction to areas susceptible to flooding within the counties of San Bernardino, Riverside, and Orange. The need for the project is due to significant flooding along the Santa Ana River – including Santiago Creek – within Orange, Riverside, and San Bernardino counties in California, which has been documented since at least 1897. According to USACE documentation, the largest recorded flooding event by peak flow occurred in 1938 following a series of large storm events, the flooding caused at least $4,000,000 in damages within Orange County along (1938 price levels). In February 1969, a series of significant storms resulted in approximately $22,000,000 in damages within Orange County (1969 price levels) and at least twelve deaths. Unprotected banks along Santiago Creek are subject to erosion which could cause damage to residential and commercial (i.e., Oakridge Private School) developments as well as infrastructure (i.e., Villa Park Road) along the creek.

This objective of the Santiago Creek project is to safely pass the 1% annual chance of exceedance flood event (100-year storm).  The project consists of slope stabilization improvements to the Bond, Blue Diamond, and Smith Basins to reduce the risk of erosion during flood events, and improvements to the Santiago Creek channel downstream of Interstate 5 to the confluence of the creek with the Santa Ana River for erosion protection and conveyance.  

The design update for the Santiago Creek project is being funded 100% by federal funds from the Bi-Partisan Budget Act of 2018.

Project Authorization

The SARMP, including the Santiago Creek component, is authorized for construction by Section 401(a) of the Water Resources Development Act (WRDA) of 1986.

Public Review

Public review of the Draft Report was completed on November 30, 2023

Project Manager

Michael Padilla

Project Location

Cities of Santa Ana, Orange, Villa Park, and unincorporated Orange County, California

Project Area