California Code, Water Code - WAT § 56011

(a) Request the board of supervisors of a county in which the district will be located to institute proceedings to form a county drainage district pursuant to this part;

(b) Describe the boundaries of the territory which is proposed for the district;

(c) Be signed by not less than 100 owners of real property within the proposed district unless the total number of owners of real property within the proposed district does not exceed 200, in which case the petition shall be signed by a majority of such owners. If the board of supervisors finds that the petition is signed by the requisite number of owners of real property residing within the territory to be included within the proposed district, that finding shall be final and conclusive.