California Code, Streets and Highways Code - SHC § 1975

(a) Courtesy signs may be awarded by the Department of Food and Agriculture, to persons that donate a minimum of five thousand dollars ($5,000) annually to the Adopt-A-Riverway Fund.  Donors may stipulate in which county they desire the courtesy signs be placed and may request specific sign placement within the county.

(b) The Department of Food and Agriculture may enter into an agreement with a local authority for production, placement, and maintenance of courtesy signs to be awarded pursuant to this section.

(c) The costs incurred by the local authorities associated with placing and maintaining courtesy signs shall be paid for out of the Adopt-A-Riverway Fund.