California Code, Water Code - WAT § 8617.5

(a) In connection with any work done on projects authorized by the board in the repair or reconstruction of levees or other flood control works completed before June 30, 1957, the board may provide for and pay the cost of the relocation, reconstruction, or replacement of improvements, structures, or utilities that have actually existed and been in use for over 20 years, which has been rendered necessary by the work, unless payment would be contrary to any written authorization or agreement under which the improvement, structure, or utility was constructed or maintained.

(b) This section shall not apply to the relocation, reconstruction, or replacement of improvements, structures, or utilities if the work has been financed, in whole or in part, with funds under the Flood Relief Law of 1956 (former Article 6 (commencing with Section 54150) of Chapter 5 of Part 1 of Division 2 of Title 5 of the Government Code) or Public Law 81-875.