Cal. Water Code § 71610

(a) Except as provided in subdivision (b), a district may acquire, control, distribute, store, spread, sink, treat, purify, recycle, recapture, and salvage any water, including sewage and storm waters, for the beneficial use or uses of the district, its inhabitants, or the owners of rights to water in the district. (b) For a district located in a county with a population greater than 8 million persons and where 80 percent of the area of the district is included within the boundaries of a water replenishment district organized pursuant to Division 18 (commencing with Section 60000), the district shall have no authority to do any of the following: (1) Manage, control, or administer the importation of water for the storage of groundwater. (2) Store water underground except pursuant to either of the following: (A) A contract with an independent holder of adjudicated groundwater extraction rights within the boundaries of the district and for the account of the water rights holder. (B) A court order issued by a court having jurisdiction over the adjudication of groundwater extraction rights within the groundwater basin where storage is sought.