Cal. Harb. & Nav. Code § 6941

Annually on or before the date set for the consideration of the budget by the board of supervisors of each county in which the district, or any portion thereof, is located, the board of each district shall furnish to the board of supervisors of each county in which the district is situated, an estimate in writing of the amount of money necessary for all purposes by the district during the ensuing fiscal year. Upon approval by the board of supervisors of each county, in which any lands lie within the district, the board of supervisors of each county shall levy a special tax, on all taxable property of the county lying within the district, sufficient in amount to raise the county’s proportionate amount of the sum required.