Cal. Pub. Util. Code § 90850

Any territory annexed in accordance with law to any city included in the district shall, upon the completion of such annexation proceeding, be deemed incorporated into and annexed to the district, and thereafter is subject to taxation, along with the entire territory of the district in accordance with the assessable valuation of the property thereof, for general district purposes, and for the payment of any indebtedness theretofore or thereafter incurred by the district.