Cal. Pub. Util. Code § 29660

One or more special service districts for any of the purposes in which the district is authorized to engage may be created within the boundaries of the district. Such special service districts may consist of one or more cities, with or without unincorporated territory, or unincorporated territory alone. Cities or unincorporated territory included within a special service district may be in the same or separate counties and need not be contiguous. No city shall be divided in the formation of such special service district, but a city may be in more than one special service district formed under this chapter.