Placerville Municipal Code Ch. 19 Fire Hazard Severity Zones

"Hazard," in the context of FHSZs, refers to the physical conditions that create a likelihood and expected fire behavior over a thirty (30) to fifty (50) year period, without considering mitigation efforts. "Risk" considers the potential damage a fire can do under existing conditions, accounting for mitigation measures like fuel reduction, defensible space, and fire-resistant building construction. In other words, hazard assesses the inherent flammability of an area, while risk evaluates the potential for damage given the existing safeguards.

(Ord. 1726, 4-22-2025)

CAL FIRE uses a model that assesses the probability of an area burning and its potential fire behavior. This model incorporates factors like fire history, vegetation, flame length, blowing embers, proximity to wildland, terrain, and weather. The model considers fire behavior and ember spread, both of which are key determinants for buildings being threatened.

(Ord. 1726, 4-22-2025)

The updated model utilizes a two (2) km grid of climate data covering 2003-2018 to adjust fire intensity scores based on temperature, humidity, and wind speed. Ember transport is also modeled using local distributions of observed wind speed and direction, rather than generic buffer distances. This results in more accurate and localized assessments of fire hazard.

(Ord. 1726, 4-22-2025)

FHSZs are primarily found in State Responsibility Areas (SRA), where the state has financial responsibility for wildfire protection and prevention. Senate Bill 63 (Stern, 2021) expanded FHSZs into Local Responsibility Areas (LRA) by requiring the identification of Moderate and High Fire Hazard Severity Zones along with Very High FHSZ.

(Ord. 1726, 4-22-2025)

FHSZs can influence defensible space standards, wildland-urban interface building codes, and real estate disclosures. In Local Responsibility Areas, California's WUI building codes apply to new buildings in High and Very High FHSZs, and local ordinances may require ignition-resistant construction for remodels. Owners must also maintain defensible space, typically one hundred feet (100'), around buildings in Very High FHSZs.

(Ord. 1726, 4-22-2025)

Insurance companies use risk models that differ from hazard models. While insurance risk models may include data used to determine Fire Hazard Severity Zone such as fuel loading, slope and fire weather, these models also incorporate additional factors that change more frequently than those in CAL FIRE’s hazard mapping.

(Ord. 1726, 4-22-2025)

While both maps consider similar factors, the CPUC High Fire Threat District Map is designed specifically to identify areas with increased risk for utility-associated wildfires. The CPUC map focuses on where fires start, considering historical powerline-caused wildfires and current fuel conditions. In contrast, FHSZs map areas where potential fires may cause impacts.

(Ord. 1726, 4-22-2025)

Local agencies are required to designate, by ordinance, moderate, high, and very high Fire Hazard Severity Zones within one hundred twenty (120) days of receiving recommendations from the State Fire Marshal. While they cannot decrease the level of fire hazard severity identified by the State Fire Marshal, they can increase it. To increase the designation to Very High, a local agency must have substantial evidence that the requirements of Government Code section 51182 are necessary for effective fire protection. They may increase the designation to Moderate or High, or include areas not identified as being in a FHSZ and designating it as Moderate or High, at its discretion.

For further information on Fire Hazard Severity Zones:

https://www.paperturn-view.com/cal-fire-communications/lra-legislation-factshee t-flipbook-combined?pid=ODg8841799&p=20&v=4

To discuss Fire Hazard Severity Zones with the City of Placerville, please send your questions to: [email protected].

(Ord. 1726, 4-22-2025)