If the board of supervisors determines, with respect to a petition for annexation filed in conformity with this chapter, that
the board, in addition to those proceedings required by Chapter 12, shall by resolution entered in its minutes, declare the annexed territory established as a temporary zone with boundaries coterminous with the boundaries of the territory annexed, designating the zone by an identifying name or number; and shall specify the purposes and duration thereof, not to exceed three years from the beginning of the next ensuing fiscal year in which a special tax or assessment levy may be made therein.
Ca. Sts. and High. Code § 19306