Cal. Sts. & Hy. Code § 5821.2
If the board of supervisors in its resolution of intention declares its intention to order the territory within which the improvements are to be constructed annexed to an existing maintenance district, the notice of improvement shall likewise give notice of such declaration of intention and that protests against such annexation may be filed and will be heard in accordance with the provisions of this chapter at the time and place provided for the hearing on the resolution of intention to perform the work.
The board of supervisors shall acquire jurisdiction to order the annexation of such territory to an existing maintenance district by giving notice within the territory proposed to be annexed in the same manner prescribed in this division for the acquiring of jurisdiction to order the construction of improvements, and within the district to which such territory is proposed to be annexed by giving notice as is provided to be given in such district by Section 5838.
Ca. Sts. and High. Code § 5821.2