New Maps Show Fire Risk in Castro Valley

“ZONE ZERO”: The Castro Valley area is no stranger to wildfires such as this vegetation fire near the 17000 of Lake Chabot Road in unincorporated Alameda County which spread to approximately six acres in July of 2023.

California updated its fire-risk maps for the Bay Area last month, and some Castro Valley homeowners will need to take additional precautions against wildfires.

The state's Department of Forestry and Fire Protection (CalFire) released the revised maps on February 25. While years in preparation, they came soon after a February 6 executive order by Governor Newsom to reduce wildfire risks in the most vulnerable areas. The map's boundaries are jagged, though, rather than closely following street layouts.

The effects on homeowners' insurance availability and costs depend on how insurance companies react to the new risk assessments. Homeowners, mostly in other parts of the state, have seen premiums increase or renewals refused as wildfire risk has grown in recent years.

CalFire says homeowners in the very-high-risk areas are now considered to be in a "zone zero" where precautions must be taken from flames and embers thrown off by fires burning some distance away. Experience from recent wildfires around the state has shown that embers, not flames, cause most structure loss in wildfires, fire officials said in a statement. Wildfires once underway can spread to areas initially at lower risk, as they did in Los Angeles.

The Alameda County Fire Department did not immediately provide details on where risks have changed from previous maps in unincorporated areas like Castro Valley.

However, the recent map shows that homes in wooded areas descending from nearby Lake Chabot, Cull Canyon, Crow Canyon, and Five Canyons Park areas are in the CalFire's "zone zero" (very-high-risk) or high-risk categories. Some of Castro Valley's most northerly or easterly homes, usually on hills, fall into the very high-risk category, and as one moves downhill the designation changes first to high-risk and then to moderate-risk and eventually no unusual risk.

The parkland south of Fairmont Drive is also at very high risk, and homes nearby, as one descends southbound down Lake Chabot Road, start out at very high risk, drop to high risk and then moderate risk. By the time one reaches Sydney Way, homes are at no increased fire risk.

CalFire says residents should consider creating a "defensible space" at least five feet closest to buildings and as far out as 100 feet for homes in very high-risk areas. This includes removing dead plants and creating space between trees and shrubs. Draft regulations might also include precautions like requiring mesh over house vents to prevent embers from reaching the inside of a house.

Homes south of Seven Hills Drive and Seaview Avenue, and west of Greenridge Road are generally not at high fire risk. So are some blocks just north of Seven Hills and Seaview.

Outside of Castro Valley, the areas considered at greater wildfire risk have grown, including parts of the North Bay. Other cities nearby wooded areas, such as Berkeley, saw their fire risk reduced after local precautions were taken.

You can see the new maps at https://experience.arcgis.com/experience/6a9cb66bb1824cd98756812af41292a0.

Scroll down past the map of State Responsibility Areas and click on the plus sign by Local Responsibility Area Fire Hazard Severity Zone Maps. Then click on "FHSZ recommendations in LRA viewer." Enter your address by the question mark in the upper left hand corner; the grid sign next to it lets you change the background on the map to show streets.

You can also zoom the map to show what streets are in what zones. If your address appears on the map without a solid colored background, you are not at unusual risk for wildfire. If you are asked to sign in, try a different browser. The information is supposed to be public without restriction.