When the board declares that charges are to be added to the annual assessment and the district is availing itself of assessments made by the assessor of any county in which the district is situated, the board shall include in the statement of the tax rate to be transmitted to the county auditor the amount of each of the charges to be levied, and the auditor shall make the charges a part of the assessment in accordance with the statement.
Ca. Pub. Util. Code § 16472