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Santa Ana River Project-Flood Control Improvements

The Santa Ana River Project (SARP) Updates

The Santa Ana River Mainstream project is designed to provide flood protection for more than 3.35 million residences and business in the Southern California communities of Orange , Riverside , and San Bernardino Counties. All three counties, collectively, are working closely with the U.S. Army Corps of Engineers to design and construct the project.

The plan for flood control improvements includes three principal features:


SARP Mainstream Plan

  • Construction of Seven Oaks Dam (about 38 miles upstream of the existing Prado Dam) with a gross reservoir storage of 145,600 acre-feet.   Cost $534 million Began: 1994 Completed: 1999
  • Enlargement of Prado Dam to increase reservoir storage capacity from 217,000 acre-feet to 362,000 acre-feet.
    Cost $880 million –Began: 1996 Expected Completion: 2021
  • Lower Santa Ana River channel modification for flood control along the 30 miles of the Santa Ana River from Prado Dam to the Pacific Ocean.  Cost: $618 million – Began: 1989 – Expected Completion: 2020

The project includes environmental features such as enhancement of a degraded marsh area at the mouth of the river, thereby providing significant value as wetland habitat for migrating waterfowl and the California least tern, a federally listed endangered species.

The plan provides for the acquisition of Wildlife and biological mitigation lands, restoring temporary loss of habitat values, cultural mitigation, and a 32 mile system of recreation trails including

Prado Dam is an existing facility constructed by the Corps of Engineers in 1941. The plan of improvement for the Prado Dam and reservoir,  includes:

Prado Dam

  • Raising the existing embankment 28.4 feet to an elevation of 594.4 feet – Completed.
  • Raising the spillway crest from elevation of 543 ft. to 563 ft – Planned for 2021
  • Constructing new outlet works increasing the maximum discharge capacity to 30,000 cfs – Completed.
  • Constructing new levees and dikes- Underway
  • Acquiring over 1,700 acres of property rights for reservoir expansion –Underway
  • Relocating and protecting 30 various utility lines- Underway
  • Increasing reservoir area from 6,695 acres to 10,256 acres.
  • Increasing-impoundment from 217,000 acre-feet to 362,000 acre-feet.