California Code, Public Resources Code - PRC § 35122

Notwithstanding Section 35120, after the establishment of the authority's boundaries, the boundaries of the authority may be altered by the annexation of contiguous territory, in the unincorporated area of a neighboring county, pursuant to the annexation process in the Cortese-Knox-Hertzberg Local Government Reorganizing Act of 2000 (Division 3 (commencing with Section 56000) of Title 5 of the Government Code).  The board of supervisors of the neighboring county shall pass a resolution stating its intent to be included within the authority's jurisdiction before any territory in that county may be annexed to the authority.