Cal. Water Code § 60251

The board shall determine the amounts necessary to be raised by taxation during the fiscal year and shall fix the rate or rates of tax to be levied which will raise the amounts of money required by the district, and within a reasonable time previous to the time when the board of supervisors is required by law to fix its tax rate, the board shall certify to the board of supervisors a statement in writing containing the following: (a) an estimate of the minimum amount of money required to be raised by taxation during the fiscal year for the payment of the principal of and interest on any bonded debt of the district as it becomes due; (b) a statement that the entire district was benefited by incurring the bonded indebtedness; (c) an estimate of the minimum amount of money required to be raised by taxation during the fiscal year for all other purposes of the district.