Scope of PG&E power shutoffs affected in part by proximity to substations

Parts of Santa Rosa, Petaluma, Rohnert Park and Napa are less likely to be affected by PG&E’s planned power outages to prevent wildfires due to layout of electric substations, according to new information the utility released Friday.

PG&E on Friday released maps of each county in its service area as well as an interactive map showing parts of California that are more and less likely to see their power cut during periods of hot, dry, windy weather that pose higher risk for catastrophic wildfires.

The maps can be accessed at pge.com or at bit.ly/PGEMaps. Zoom in on the map below for a closer look.

The interactive global map shows more vulnerable areas with blue blobs in contrast to the orange swaths that show similar information in the utility’s county-specific maps. The Press Democrat previously obtained a map of Sonoma County that PG&E had shared with local officials but had not released to the public. The county, in turn, acceded to PG&E’s request by publishing only a blurred version that was largely illegible.

The highlighted areas on the latest map “show the areas that are more likely to be shut off for safety when gusty winds and dry conditions, combined with a heightened fire risk, are forecasted to threaten a portion of the electric system,” according to PG&E. Nonhighlighted areas are less likely to be affected, though no PG&E customers are immune.

The map includes pockets of land in Sonoma County, such as west Santa Rosa, northern Rohnert Park, northern Napa, and parts of Petaluma, that are not highlighted, while much of the surrounding area is.

The arrangement puzzled emergency officials when they first got hold of the PG&E maps earlier this month, records showed.

Chris Godley, the county’s emergency management director, sent an emailed question to a PG&E representative, asking how that could be the case.

“The question coming up is how you can have an island of power surrounded by circuits that could be de-energized,” Godley wrote in the email. “Sonoma County map attached here - how can power stay on in west Santa Rosa if it gets cut all around it?”

Neil Bregman, Santa Rosa’s emergency preparedness coordinator, was copied on Godley’s email, and echoed the inquiry: “Good question.”

The PG&E representative, Herman G. Hernandez, replied that he was “working on this as I type” and hoped to provide more information before the following day’s Board of Supervisors meeting

Emails in the exchange were obtained by The Press Democrat through a records request with the city of Santa Rosa. Jeff Smith, a PG&E spokesman, provided more clarity Friday in an email to the newspaper.

“As far as your ‘island of power’ question, there are substations very close to this area of Santa Rosa,” Smith said, “and circuits or portions of circuits not within the High Fire-Threat District wouldn’t be impacted unless there was a (planned shutoff) that required de-energizing high-voltage transmission lines.”

Smith declined to comment on specific communications between city officials and PG&E, saying that “would not be appropriate.”

The utility has repeatedly cautioned that, because its grid is linked and its new plan of combating wildfires includes shutting off transmission lines that carry juice across California, any of its electric customers might have their lights cut if PG&E determines the risk of equipment causing a fire is greater than the complications from indefinite outages.

The utility’s equipment has been held responsible for sparking many of the most destructive wildfires in the state in the past two years.

The new map does not allow viewers to enter their addresses, but savvy web browsers may be able to zoom in close enough to see whether their home or business is more or less likely to be affected by a planned shutoff.

PG&E noted that its planning maps will be “refined and updated” as the year goes on and asked customers to check back regularly. Other maps related to specific outages will be updated as needed.