On December 14, 1989, the U.S. Army Corps of Engineers (COE) and the County Flood Control District of Orange, Riverside and San Bernardino as Local Sponsors, entered into a four-party Local Cooperation Agreement (LCA) defining the responsibilities and cost-sharing of each party for each feature.
The Local Sponsors are to acquire all lands, easements, rights-of-way and perform relocations required to make way for construction of the Mainstem Project. The COE will construct the improvements. On completion, the Local Sponsors are responsible for the operation and maintenance of the Project features; except for Prado Dam where Orange County is responsible to pay for incremental operations/maintenance costs and the COE will continue to operate the Dam.
Congress authorized Santa Ana River Mainstem Project for construction in 1986 under new guidelines for cost sharing of water resources projects between Federal and local governments. The local sponsors must pay between 25% and 50% of total cost of the project with the remaining cost provided by the Federal government.
In 2003, a new agreement was entered between the Corps of Engineers and Orange County Flood Control District where Prado Dam feature of the Santa Ana Mainstem Project was separated and Orange County was a sole local sponsor for Prado Dam.