Health and Safety Code § 40324

Any vacancy on a regional district board shall be filled by appointment in the same manner as the vacating member was appointed.

Any member of a regional district board may be removed at any time in the same manner as he was appointed. If four-fifths of the members of the board of supervisors of a county request the removal of a member appointed by the city selection committee of such county, the city selection committee of such county shall meet within 20 days to consider the removal of such member.