Introduction to Updated Fire Maps

The California Department of Forestry and Fire Protection has released updated fire-hazard severity-zone maps for Los Angeles County, marking the first update in over a decade. These maps add more than 440,000 acres to the county’s hazard zones, including a 30% increase in acres zoned in the highest severity rating. This release is part of a statewide rollout that began two months ago and includes all of Southern California.

Impact on Los Angeles County

The city of L.A. saw its acreage in the “very high” zone increase by 7%. The addition of the new “moderate” and “high” zones led to the total acreage in the fire severity hazard zones increasing by 24%. However, the unincorporated areas in L.A. County that rely on the Los Angeles County Fire Department (LACFD) saw their acreage in the “very high” zone more than triple. Much of the unincorporated areas, which make up over 65% of the county and include Altadena, the outskirts of Santa Clarita and Palmdale areas, and Puente Hills near Whittier, are wildlands or exist at the wildland-urban interface, which are more prone to fire.

Statewide Implications

With the rollout complete, California as a whole now has more “very high” hazard zone acres than ever before. Cal Fire mapped a grand total of 6.8 million acres into the local responsibility area hazard zones: “very high” zones grew 35%, from 860,000 acres to nearly 1.2 million; meanwhile, 1.2 million and 4.5 million acres were placed into the new “high” and “moderate” zones, respectively. The hazard severity zone maps are referenced in more than 50 sections of California law, requiring homeowners in “high” and “very high” hazard zones to follow fire-safe building codes for new construction.

Regulations and Enforcement

Homeowners in the “very high” zones must maintain defensible space around their properties and disclose the “very high” status when they put their houses up for sale. The legislature has also required local governments in heightened severity zones to routinely review evacuation routes and account for the potential peak stress on water supplies during a disaster. Local governments must also locate essential public facilities like hospitals and emergency command centers outside of heightened fire hazard zones “when feasible,” according to the law.

Mapping Methodology

Cal Fire research manager David Sapsis acknowledged that the models Cal Fire uses to create its maps cannot fully predict the dynamic spread of wildfire into urban areas. Cal Fire’s model instead accounts for the vegetation type, topology, climate, and weather for wildland areas to calculate the probability of an area burning and the likely intensity of the blaze. From this, it calculates how far a blaze would likely spill over into urban areas. Other companies, like First Street, approach it somewhat differently, creating a virtual representation of California that includes both vegetation and human infrastructure of the state’s urban areas, and simulating how fires would likely spread, including into areas like Altadena.

Local Jurisdictions’ Response

Local jurisdictions have 120 days to accept public input on the maps and work with Cal Fire to issue an official ordinance implementing them. Typically, ordinances take effect about 30 days after they’re issued. At that point, the heightened fire safety regulations would apply to the new zones. Local jurisdictions like L.A. city and county are allowed to increase the severity of a zone and add additional acres to a zone; however, they cannot decrease the severity of zones or remove acres from them.

Conclusion

The updated fire-hazard severity-zone maps are a critical tool for identifying high fire hazard areas and strengthening fire safety policies across communities. Fire safety advocates have attributed the continuing upward trend of acre zones to a litany of factors, from development in fire-prone areas, ecosystem changes, and climate change. As California continues to face the threat of wildfires, these maps will play a vital role in guiding rebuilding efforts and ensuring that homes and infrastructure are rebuilt with safety and resilience in mind.

FAQs

1. What are the fire-hazard severity-zone maps, and why are they important?
   The fire-hazard severity-zone maps are used to identify areas that are prone to wildfires and to guide fire safety policies. They are important because they help to ensure that homes and infrastructure are built with safety and resilience in mind.
2. How often are the fire-hazard severity-zone maps updated?
   The fire-hazard severity-zone maps are updated periodically, with the most recent update being the first in over a decade for Los Angeles County.
3. What factors contribute to the increasing acreage in fire hazard zones?
   Factors such as development in fire-prone areas, ecosystem changes, and climate change contribute to the increasing acreage in fire hazard zones.
4. How do local jurisdictions respond to the updated maps?
   Local jurisdictions have 120 days to accept public input on the maps and work with Cal Fire to issue an official ordinance implementing them. They can increase the severity of a zone and add additional acres to a zone but cannot decrease the severity of zones or remove acres from them.
5. What is the role of companies like First Street in fire hazard mapping?
   Companies like First Street create virtual representations of California that include both vegetation and human infrastructure of the state’s urban areas, simulating how fires would likely spread, including into areas like Altadena. Their approach is different from Cal Fire’s, and they may use their models to identify areas at risk of wildfires.