Cal. Pub. Util. Code § 90870

From and after the date of annexation, the board shall levy upon all of the property in the city annexed, such taxes, tolls, or charges as are necessary to provide funds for the payment of the indebtedness assumed by the city or otherwise necessary to comply with the terms and conditions of the annexation agreement, all in addition to the general district taxes authorized elsewhere in this division to be levied and collected.