USACE Los Angeles District

04/23/2021 | Press release | Distributed by Public on 04/22/2021 21:30

Chief of Engineers signs report recommending ecosystem restoration in Prado Basin


The U.S. Army Corps of Engineers' top general signed a report April 22 - on Earth Day - recommending a plan to restore more than 600 acres of valuable riparian habitat within the largest riparian forest in Southern California.

Lt. Gen. Scott Spellmon, the Corps' commanding general and 55th U.S. Army chief of engineers, signed the Chief of Engineer's Report for the Prado Basin Ecosystem Restoration and Water Conservation Feasibility Study at the Corps' headquarters in Washington, D.C. The project is headed by the Corps' Los Angeles District, in partnership with the Orange County Water District.

During the signing, the general thanked the LA District and Orange County Water District for their hard work and collaboration on the study, while also recognizing the significance of signing the report on Earth Day.

'Today is Earth Day. This is a great message to approve for today,' Spellmon said. 'I want to thank (Col.) Julie (Balten) and her staff. Great work by your planners and all our partners in Orange County … really well done. I'm really proud of this work.'


The project area, which is nestled along the Santa Ana River about 50 miles southeast of downtown Los Angeles, is within one of the world's top 25 most biologically rich and threatened terrestrial ecosystem regions. It is a critical wildlife corridor - downstream of Prado Dam - which connects the public lands of Chino Hills State Park, Cleveland National Forest and the southwestern flyway.

The project aims at restoring riparian and associated habitats suitable to native species; reducing the presence and effects of non-native wildlife; and providing critical habitat for threatened and endangered species, including birds like the least Bell's vireo and southwestern willow flycatcher.

The cost of the ecosystem restoration project is about $46 million and is the most cost effective and efficient plan for restoring aquatic, riparian and floodplain habitats along the Santa Ana River Mainstem upstream, downstream of Prado Dam, and along the Mill Creek and Chino Creek tributaries.

During the signing, Balten recognized the Orange County Water District for its continued partnership, commitment and investment in the project, as well as the work of the LA District team for its 'amazing work and dedication that was demonstrated during the entire study.'

'The LA District is excited to be a part of this important project and is especially happy to mark the occasion on the 51st anniversary of Earth Day,' said Col. Julie Balten, LA District commander. 'We look forward to continuing the great partnership we have with the Orange County Water District, as well as Orange, San Bernardino and Riverside counties, to restore critical habitat within this region.'

The Orange County Water District also reciprocated its gratitude to the Corps for getting the project from the study phase to the Chief's Report.

'The Orange County Water District would like to thank the (Corps) for the great partnership that has culminated in the signing of the Chief's Report for our project,' said Stephen Sheldon, president of the Orange County Water District Board of Directors.'

With Spellmon's recommendation for approval, the report is now elevated to the Assistant Secretary of the Army for Civil Works, U.S. Office of Management and Budget, and to Congress for consideration of project authorization.


The Santa Ana River watershed is about 2,650 square miles and is located within San Bernardino, Riverside and Orange counties. The study area is primarily within the footprint of the Santa Ana River Mainstem Project and includes Prado Basin and extends for seven miles downstream of Prado Dam.

Prado Dam and Basin was built in 1941 and serves as the principle regulating project on the Santa Ana River. Its primary authorized purpose is flood-risk management, followed by water conservation and recreation.


In addition to ecosystem restoration, the study also recommended increased water conservation at Prado Basin, which has the potential to provide Orange County with up to 13,000 additional acre-feet of groundwater annually, supporting about 60,000 residents, while also reducing reliance on more costly imported water.

The National Economic Development Plan for water conservation has been approved by Brig. Gen. Paul Owen, commander of the Corps' South Pacific Division, and is ready for implementation in time for the next rainy season.