California Code, Public Utilities Code - PUC § 70061

The city members of the governing body of the district shall serve for terms of two years commencing on the first Monday of January in each even-numbered year, and until their successors are selected and qualified.  If a city member ceases to be a mayor or councilman during his term, his membership on the governing board shall thereafter be considered vacant.

The city selection committee shall meet at the call of the chairman of the governing body, or at the request of 60 percent of the members of the committee, to fill vacancies and make selections for prospective terms, on the governing body.