Cal. PUC § 31407

If territory is annexed to a city or consolidated with a city, the corporate area of which has been included in the district, or, if a new city is incorporated, a portion of which is within the district, such annexed, consolidated, or incorporated territory as is not already within the district shall simultaneously with its annexation to the city or consolidation with a city or its incorporation as a city be annexed to the district, and shall become and be, an integral part of the district and the taxable property therein shall be subject to taxation thereafter for all purposes of the district, including, without limitation, the payment of bonds and other obligations of the district at the time authorized and outstanding, and the board of directors of the district shall be empowered to do all things necessary to enforce and make effective this section.