California Code, Public Resources Code - PRC § 4145

(a) It is the intent of the Legislature that cooperative agreements that are entered into between the department and a local government shall provide for the equitable sharing of costs associated with capital outlay projects that enlarge, enhance, or replace facilities for the purposes of benefiting the cooperating local government.

(b) The department shall prescribe those terms and conditions for those cooperative agreements that would result in an equitable sharing of those costs in proportion to the benefits derived, including any in-kind, lump-sum, or installment payments.  Any installment payment made in connection with a cooperative agreement entered into pursuant to this section shall be made over a period of time not exceeding a maximum of 20 years at the same rate of interest as the rate for the state's Pooled Money Investment Account.  Any money that is received for reimbursements for facility improvement costs, under a cooperative agreement, shall be deposited in the General Fund.