Cal. Wat. Code § 75472
The district may, by resolution of the board, provide a procedure for and collect the charges by way of the tax bills of the county in which the district is located. The charges shall appear as a separate item on the tax bill, shall be collected at the same time and in the same manner as county ad valorem property taxes are collected, and shall be subject to the same penalties and the same procedure and sale in case of delinquency as provided for those taxes.
The district shall, on or before August 1st of each year, certify to the county auditor the charges to be collected. The county may deduct from the revenue so collected for the district an appropriate amount for the billing and collection services rendered to the district.
Ca. Water Code § 75472