Cal. Wat. Code § 12716
The project for flood protection on Walnut Creek in Contra Costa County is adopted and authorized substantially in accordance with the recommendations of the Chief of Engineers in House Document Numbered 76, 86th Congress, First Session, as authorized by Act of Congress approved July 14, 1960 (Public Law 86-645, 74 Stat. 480, Title II, the "Flood Control Act of 1960") at an estimated cost to the State of such sum as may be appropriated for state co-operation by the Legislature upon the recommendation and advice of the department, when funds for carrying out the project are appropriated by Congress; provided, that the requirement that local interests make a cash contribution to the United States equal to 7.4 percent of the project cost is for payment of local benefits not related to flood control and shall not be payable or reimbursable by the State.
Ca. Water Code § 12716