Cal. Water Code § 31033

A district may drain and reclaim lands within the district either by surface or underground works or both; and may acquire, by appropriation or other lawful means, and divert, store, conserve, transport or dispose of water resulting from such operations; and may acquire, by appropriation or other lawful means, and divert, store, conserve, transport or dispose of flood and storm water within the district, and flood and storm water of streams or watercourses outside of the district which flow into the district, for any beneficial purpose or use.