Cal. Sts. & High. Code § 27201

During July of each year the board shall determine the amount of money required by the district which must be raised by taxation, and shall fix a rate of taxation which will raise that amount. If the purpose of the taxation is to supply funds for investigating the project prior to the issuance of bonds and the payment of the officers and employees of the district prior to the time when the works of the district are earning revenue the tax rate shall not exceed ten cents ($0.10) on each one hundred dollars ($100) of assessed valuation.