A San Mateo County Civil Grand Jury report released on July 9 warns residents of urban areas not to be complacent about wildfires since high winds can drive swarms of embers long distances and ignite vulnerable structures.
The report citing the threat to city residents comes as towns in the so-called urban/wildland interface, such as Portola Valley and Woodside, are trying desperately to find ways to prevent fires as well as prepare an effective response if they do occur.
The Grand Jury identified about 35 percent of land in the county as a place where a wildfire could start. But, there is no guarantee that the flames won't move on from there to more populated urban areas, the report said.
"High winds moving through gaps in the coastal range could expand the perimeter of a fire quickly, making it a countywide threat to lives and property," the report said.
While fire suppression activities confine most fires to two acres or less, certain wind conditions could render a fire in a rural area unmanageable and cause it to spread rapidly across a much larger area, according to the report.
The Crystal Springs reservoirs, San Andreas Lake and Interstate 280 could act as a firebreak and "slow the eastward progress of a fire towards San Francisco Bay."
However, the report noted, wind-driven fires have produced embers that have jumped rivers and reservoirs in the past.
Jonathan Cox, division chief for the California Department of Forestry and Fire Protection's San Mateo-Santa Cruz Unit, told The Almanac that he agrees with the report's conclusions and pointed to the Coffey Fire in Santa Rosa in 2017 that destroyed more than 5,000 structures in an urban residential area as an example.
"Any of these fires that are burning under high-wind conditions can throw embers miles ahead of themselves," Cox said. "If that hits a wood shake roof or a wood deck it can have an effect the same way as a structure in the wildland would."
One large fire can trigger dozens of small fires miles away, Cox said.
The report also called for educating the public countywide about evacuation routes, noting that "all emergency notification systems can be compromised during a conflagration, which makes advanced public knowledge of alternative evacuation routes crucial for public safety."
That information could be included as an enclosure that could be published by local fire agencies and sent to homeowners with their property tax or utility bills, the report suggested.
So far, four communities in the county, including Portola Valley, Woodside, La Honda, and Palomar Park, containing less than 2% of the county's population, publish information sheets about escape routes.
Jeff Norris, coordinator for the San Mateo County Office of Emergency Services, cautioned that residents need to have several ways to escape in mind and should get information about the direction the fire is moving so they can to decide the best way to evacuate.
Norris recommended that residents subscribe to San Mateo County Alert, a reverse 911 system that sends a text, email or voice mail message that gives early warning information about fires, road closures, hazardous materials releases and other incidents.
San Mateo County Alert has 100,000 subscribers out of a total county population of 760,000, he said.
Norris agrees with the Grand Jury's opinion that emergency alert systems aren't foolproof, saying that the need for flexibility is the only constant.
"If you think you're in danger, don't wait pack up and move to a different area," he said in an interview with The Almanac.
The county has a mutual aid arrangement between fire protection agencies that enables them to pool their resources; however, multiple fires could strain their ability to respond, according to the report.
To counter the problem, the Grand Jury recommended obtaining funds from the California Office of Emergency Services to place fire engines in high-risk wildfire areas areas during periods of high fire danger.
"Cal Fire can move resources in anticipation of fire danger," Cox said. "It can staff additional equipment and bring in additional resources."