CA Pub Res Code Section 9188

If the majority of the votes cast at the election is in favor of forming the district, the board or boards of supervisors shall by resolution entered on its minutes declare the district duly organized under this division, giving the name of the district, and the purposes for which it is formed, and describing its boundaries. If the district lies in more than one county, the clerk of the board of supervisors of the principal county shall transmit a certified copy of the resolution to the clerk of the board of supervisors of each of the other counties in which the district lies.