LAFCO is responsible for establishing, amending, and updating spheres of influence for all cities and special districts within its jurisdiction. State law defines a sphere of influence as “the probable physical boundary and service area of a local agency.” All boundary changes, such as annexations and detachments, must be consistent with the spheres of influence of the affected agencies with limited exceptions.

LAFCO generally reviews and updates the spheres of influence for all cities and special districts every five years. Interested parties may request LAFCO consider a specific sphere of influence amendment as part of the agency’s regular review and update process. Interested parties may also request LAFCO consider a sphere of influence amendment in advance of its regular review and update schedule. Interested parties requesting a sphere of influence amendment must complete a questionnaire and submit a deposit in an amount determined by the Executive Officer.   

Maps depicting the adopted spheres of influence for all cities and special districts in Napa County are provided below.