California Code, Public Utilities Code - PUC § 2774.5

An electrical corporation or local publicly owned electric utility shall immediately notify the Commissioner of the California Highway Patrol, the Office of Emergency Services, and the sheriff and any affected chief of police of the specific area within their respective law enforcement jurisdictions that will sustain a planned loss of power as soon as the planned loss becomes known as to when and where that power loss will occur.  The notification shall include common geographical boundaries, grid or block numbers of the affected area, and the next anticipated power loss area designated by the electrical corporation or public entity during rotating blackouts.