California Code, Public Utilities Code - PUC § 90170

The government of the district shall be vested in a board of directors elected concurrent with the district's formation.  If no unincorporated area of the county is included within the district, the City of San Diego shall elect seven directors at large.  If any unincorporated area of the county is included within the district, the City of San Diego shall elect eight directors at large.  Each of the incorporated cities within the remaining section as specified in Section 90050 and the unincorporated area of the county, if any, shall elect one director.  In the event of a tie, the directors involved shall determine by lot which shall be seated.

Whenever any additional member is elected to the board of directors as a result of any annexation to the district, the City of San Diego shall be entitled to seat an additional member on the board of directors.  The City Council of the City of San Diego shall appoint any initial additional member to which the city becomes entitled and such member shall serve until a successor is elected at the next succeeding election of directors within the City of San Diego and qualifies.