By David R. Baker

California utility regulators on Friday finally approved a statewide map, years in development, designed to help prevent power lines from starting wildfires.

The detailed map, which shows the risk of utility-related fires in different parts of the state, will govern how electric companies maintain their equipment in the field. Stricter regulations -- on inspection schedules and tree-trimming around power lines -- will apply in areas facing an elevated or extreme risk of wildfires.

The map's approval, by the Safety and Enforcement Division of the California Public Utilities Commission, caps a nearly decadelong process of creating tougher fire regulations for the state's electric utilities.

The effort began after electrical equipment sparked wildfires in San Diego County in 2007. But the commission adopted new regulations for most of the state only in December, after last fall's deadly, wind-driven wildfires in the North Bay and Southern California.

Those regulations, in turn, depend on the map, whose development was overseen by an independent group of experts assembled by the California Department of Forestry and Fire Protection, or Cal Fire. The process of creating the map proved complex, forcing the commission to extend several times the deadline for finishing it.

In areas designated as facing the highest risk of fire, the new safety regulations will take effect Sept. 1. In places facing an elevated but not extreme fire risk, the regulations will apply starting on June 30, 2019. Utility companies will be required to file an annual report detailing their plans for preventing fires in high-risk areas, with the first report due on Oct. 31 of this year.

Although Cal Fire has not determined the causes of most of last fall's fires, investigators are exploring the possibility that power lines blown by fierce winds prompted them.

With the new rules and the map finally in place, the commission will hold a daylong public meeting on Jan. 31, at the commission's San Francisco headquarters, to discuss whether additional steps are needed to prevent utility equipment from starting fires. State senators and assembly members from the North Bay will hold a hearing on the same subject on Jan. 26 at Santa Rosa City Hall.

(c)2018 the San Francisco Chronicle