‘Very high’ wildfire zones surge in parts of San Mateo County

“The modeling that’s being used is accounting for flying embers, which previously was not as accurately understood when it was last done,” Jed Wilson, fire chief for the Coastside Fire District, said. “We have more technology and data now, and it also takes in extremely windy and dry conditions with up-to-date climate data … and it’s also taking into consideration the fuels that are available to burn in that area.”

Half Moon Bay, Pacifica and unincorporated areas saw some of the largest increases. The former now has more than double the number of acres listed as “very high” in its new map compared to 2011. An additional 1,050 acres are considered high severity.

Millbrae didn’t have any land listed as “very high” in the previous map, but now it shows 353 acres as “very high” and 186 acres as “high.”

For zones deemed “very high,” new construction must adhere to more restrictive building codes, known as Chapter 7a, as part of the state’s requirements. Among other stipulations, it mandates the use of ignition-resistant siding, as well as ember-resistant roofs and vents.

Per state law, existing homes are not necessarily required to be retrofitted to 7a standards, but property owners typically must undergo additional inspections and procedures when selling their home in such an area.

But the increase in “very high” areas throughout the Peninsula may push cities to go beyond state-level requirements and implement more rules for existing homes, especially given much of the county’s housing stock was built in the 1940s and 1950s. Localities cannot implement codes that are less stringent than 7a, but they can pass regulations that are more restrictive.

“That’s a policy decision that needs to be made, and we need to engage our elected officials on that,” said Dave Pucci, fire chief for Central County Fire District, which covers Millbrae, Burlingame and Hillsborough. “I didn’t expect to see a jump from one city to another within one fire district, so we will have to do some shifting around and get feedback from the community and elected officials on their direction.”

Additional regulations on existing homes could make sense in a place like Millbrae, as many of the “very high” hazard zones are already developed, Pucci added. Hillsborough had previously implemented additional rules on top of state mandates. Prior to the new maps, it had more than 1,400 acres listed as “very high.” Now, it has about 930 acres designated as either high or moderate. Cal Fire didn’t take into consideration local-level policies when developing the severity maps, but there could still be an appetite for keeping stringent fire protection rules at the local level.

“That community was very interested in wildfire protection, so when we go to public comment and get feedback from the elected officials in that community, I’m suspecting they’ll still want certain things that were required under the wildfire severity zones. Millbrae did not have those,” Pucci said.

Hillsborough wasn’t the only city or town to see a decrease in the amount of “very high” hazard areas. Several others saw drops in the amount of “very high” zones with the newly released map, including Redwood City, San Mateo and Belmont.

San Mateo and Belmont currently have ordinances that also go beyond 7a. For example, existing homes in the “very high” zones are subject to annual inspections, and the 7a requirements apply not just to “very high” zones — as laid out in the state mandate — but it also applies to those deemed high hazard. Property owners adding additions that are larger than 50% of their existing house must also do the low-cost retrofits listed on the state website, including vent upgrades and installing multiplane glass. The additional regulations came in large part after the district commissioned its own independent study to assess fire risk about five years ago.

Despite the state’s much-needed map update, Robert Marshall, deputy fire chief at San Mateo Consolidated Fire Department, said local jurisdictions still need to do as much as they can to assess gaps in their own communities. The state maps show wildfire risk based on a number of scientific factors, but it doesn’t factor in infrastructure challenges that could exacerbate the impact to communities in the event of an emergency.

“There are things that we have to take into consideration that [the state] process doesn’t. For example, we’ve got several roads that are very long and only have one way in or one way out. So if we had a situation where there were mass evacuations, what would that mean and how would that manifest itself?” Marshall said. “Those are things we need to look at and move through the public process.”

And just because a neighborhood isn’t in a “very high” hazard zone doesn’t mean it should be de-prioritized from risk mitigation efforts, he said, adding that much of the destruction in some of the worst wildfires in recent years — including the Los Angeles County fires — occurred in areas that were not deemed very high severity.

The state does not require insurance companies to use one standard mapping system, meaning they will most likely continue using their own methods for risk underwriting. But the maps are still helpful for local jurisdictions and fire districts to enhance project planning and possibly grant funding, Wilson said. According to the Cal Fire website, there are about 12 active fuel reduction projects the agency is working on, including work along Highway 35 and at Mills Canyon Park.

“It’s going to take some time for all agencies up and down the Peninsula to reevaluate and get the public feedback and adjust,” Pucci said. “The hazards are changing over time, and we have to change with it.”