Cal. Water Code § 39400

A majority in number of the holders of title to land irrigated or susceptible of irrigation from a common source and by the same system of works, who are also the holders of title to a majority in value of the land may propose the formation of a district under the provisions of this division or the formation of the district may be proposed by not less than 500 petitioners, each of whom is the holder of title to land therein and which petitioners include the holders of title to not less than 10 percent in value of the land included within the proposed district.