With wildfire season approaching, PG&E is again warning customers, particularly in wooded, high-fire-risk areas such as Woodside and Portola Valley, that it may shut off power during heat emergencies to avoid power lines igniting fires.

The shutoff plan was formulated following billions of dollars in liability losses from wildfires linked to sparking power lines that ignited tree branches and other vegetation.

PG&E representatives have met with San Mateo County fire chiefs to get feedback about their plans, said Rob Lindner, chief of the Woodside Fire Protection District that covers Portola Valley and Woodside and some unincorporated areas of the county.

"We're in favor of them doing whatever is necessary to keep our residents safe," Lindner said. "What we really want is for PG&E to be as transparent with the community as possible."

District officials believe that the utility can reduce wildfire risk by improving its tree trimming and other vegetation management, repairing power lines, and enhancing wildfire detection systems, including cameras and weather stations, he said.

PG&E has embarked on an extensive campaign to trim trees around power lines and inspect the lines more thoroughly throughout its service area after fire investigators blamed it for starting 17 of the 21 wildfires in California in 2017, according to a New York Times report.

"We agree that a lot needs to be done," Lindner said. "It's not just the power shutdowns, but their overall commitment to reducing wildfire risk."

There are no mandatory circumstances under which PG&E will take action to shut off power to a given area, but possibilities include a "red flag warning" declared by the National Weather Service; humidity levels of 20% and below; predicted sustained winds generally above 25 mph and wind gusts of 45 mph; conditions with dry fuel on the ground and live vegetation; and on-site observations from PG&E field crews, according to utility spokeswoman Andrea Menniti.

PG&E plans to warn residents with alerts 48 hours, 24 hours and just before a power shutoff, although the timing and frequency of the warnings may change depending on weather conditions, Menniti said.

The utility is urging customers to prepare for outages that could last more than two days, and promises that they will be contacted by phone, text and email and provided with updates through social media, news, radio and the pge.com web site.

In preparing for shutdowns, the utility recommends visiting its Community Wildfire Safety Program website. The site provides links to emergency preparedness instructions and offers tips on preparing for outages. Residents can also sign up for alerts that will be sent out in the event of a power shutoff.

Among the suggestions:

• Update contact information by visiting pge.com/mywildfirealerts or call 1-866-743-6589 during normal business hours to receive the automated calls, texts and emails.

• Plan for medical needs like medications that require refrigeration or devices that need power.

• Build or restock your emergency kit with flashlights, fresh batteries, first aid supplies and cash.

• Know how to open your garage door manually.

After a shutdown, PG&E will restore power when the weather conditions improve and after inspecting power lines, Menniti said.

Once the decision is made to turn the power back on, in most cases it will be restored within 24 hours, she said.

The San Francisco-based Utility Reform Network was critical of the power shutoff plan because it would "create safety hazards of its own," according to Communications Director Mindy Spatt.

"It would have an impact on communications because if you have a cell phone, you can't charge it when the power is gone, and many customers are dependent on electricity for medical purposes," she said.

Spatt said safety is a long-term problem with PG&E, and cited the San Bruno gas line explosion in 2010 as a problem that had nothing to do with wildfires.

"The company needs a better way of keeping people safe other than what we have now," she said.

The fire district has discussed undergrounding power lines with Woodside and Portola Valley in the face of the fire threat as well as for aesthetic reasons.

"Although it is expensive, undergrounding is a cost-effective way of reducing the (threat)," former Woodside Fire District Chief Dan Ghiorso noted at a March 27 Town Council meeting in Portola Valley.

Underground power lines may not cause fires but they can be damaged by lighting strikes, earthquakes, flooding and construction excavation, said Jeff Smith, PG&E's marketing and communications manager.

"Given the growing risk of wildfires now, we are focused on taking safety actions to minimize risks on our overhead lines," Smith said.