California Code, Public Resources Code - PRC § 5120

The board of supervisors of any county may by ordinance declare its intention to establish and maintain a museum of history, science, art, or similar objects.  After the ordinance has taken effect, the board may exercise any or all of the powers provided in this article, directly or by agents under its direction and control.  The board may exercise any other power necessary and proper to promote the objects and purposes of a museum devoted to the acquisition, exhibition, and utilization of scientific, artistic, historical, or similar material.