Cal. Sts. & Hy. Code § 5101.6
Following the levy of an assessment pursuant to this division to pay, in whole or in part, the costs and expenses of works, system or facilities authorized by subdivision (a) of Section 5101.5 upon a district benefited thereby, and annually on or before June 30th, the legislative body may prepare and approve an estimate of the expenditures required during the ensuing fiscal year for the maintenance, operation, repair and improvement of such works, system or facilities and shall deduct from such estimate the amount of revenues, if any, which the legislative body estimates will accrue during such year from the operation of such works, system or facilities and will be available to pay costs of such maintenance, operation, repair and improvement.
The legislative body may increase the assessment in accordance with the provisions of Section 53753 of the Government Code. The proceeds of the assessment shall be placed in a separate fund of the city and shall be expended only for the maintenance, operation, repair or improvement of such works, system or facilities.
Ca. Sts. and High. Code § 5101.6