Cal. Pub. Util. Code § 26406

If the board determines that the annexation of the city, whose voters have petitioned pursuant to Section 26404, would facilitate the acquisition or operation of any transit facilities for the district or be of advantage to the district, then the board shall also determine the terms and conditions upon which the annexation should be made. The terms and conditions of annexation shall be embodied in an annexation agreement. The annexation agreement may provide (among other things) for any or all of the items set forth in Sections 26402 and 26403.