California Code, Health and Safety Code - HSC § 4891

The board may levy a tax each year upon the real property in the district sufficient to defray the cost of maintaining, operating, and repairing the sewers in the district, of maintaining the district, and of meeting such other expenditures as are authorized by this chapter. The amount of taxes to be collected from the levy made upon property located within the incorporated area of a city may be paid in whole by the city, if the city elects to make such payment as provided in Section 4892.1.

If a district is divided into zones, the board of supervisors may determine what portion of the amount of money to be secured from the levy of taxes shall be secured from each zone within the district.