Cal. Wat. Code § 60317.5
Except as set forth in this section, nothing in this division prevents the use of district funds from any source for powers and functions authorized under this division. That part of a replenishment assessment levied pursuant to determinations under subdivisions (a) and (b) of Section 60316 shall not be utilized for the direct costs of prevention and removal of contaminants under subdivisions (a) and (b) of Section 60224. Any part of a replenishment assessment levied pursuant to a determination under subdivision (c) of Section 60316 which is not expended may be obligated and expended for other uses authorized by Section 60224 after hearing and findings pursuant to Sections 60306 and 60315. Any part of a replenishment assessment levied pursuant to a determination under subdivision (c) of Section 60316 which remains unexpended and unobligated for five fiscal years after the last obligation thereof, or any shorter period which the board may by resolution determine, shall be deemed to have been levied for other costs and expenses for which a replenishment assessment is authorized under this division. Funds from a replenishment assessment, although restricted as to use, may be loaned for any use for which and within the monetary limits for which, such an assessment has been levied. Any such loan shall be for a period not longer than 18 months and shall bear interest, as nearly as practicable in the discretion of the board, at the rate which those funds might have otherwise been invested at the time of the loan.
Ca. Water Code § 60317.5