California Code, Water Code - WAT § 35565.1

(a) To provide for the control of flood and storm waters of the district and the surface or subsurface streams created by storm water runoff from sources outside of the district and to conserve all the waters for beneficial and useful purposes by spreading, storing, retaining, slowing, and causing those waters to percolate, either by natural or artificial means, into the soil strata.

(b) To protect from damage from those flood or storm waters the personal or real property within the district and the lives of the inhabitants thereof.

(c) To protect, preserve, and restore watersheds within or without the district.