Cal. Pub. Res. Code § 7606

Any of the lands designated in this chapter which, by reason of periodical overflow, need, and are susceptible of, reclamation, may be reclaimed by the formation of districts, in the same manner and subject to all of the provisions of law regulating the reclamation of swamp and overflowed lands. The board of supervisors of the county in which the lands, or the greater part thereof, are situated, shall first determine, upon proper petition presented therefor by the holders of the title, or evidence of title, representing one-half or more of any body of such land, that such reclamation is necessary and feasible.