Gov. Code, § 25353

The board may purchase, receive by donation, lease, or otherwise acquire water rights or real or personal property necessary for use of the county for any county buildings, public pleasure grounds, public parks, botanical gardens, harbors, historical monuments, and other public purposes, or upon which to sink wells to obtain water for sprinkling roads and other country purposes. The board may improve, preserve, take care of, manage, and control the property. Whenever a county has been designated a successor to a harbor improvement district pursuant to Division 1 (commencing with Section 56000) of Title 6 the board of supervisors shall have the same powers and duties as the former board of directors of such district with respect to the acquisition, improvement, and management of harbors or public beaches within the county.