Cal. Water Code § 71642

A finding by the board upon the existence, threat, or duration of an emergency or shortage, or upon the matter of necessity or of any other matter or condition referred to in Section 71640, shall be made by resolution or ordinance. The finding is prima facie evidence of the fact or matter so found, and such fact or matter shall be presumed to continue unchanged unless and until a contrary finding is made by the board by resolution or ordinance.