A grass fire that erupted in the agricultural hills of Chileno Valley grew to a mapped 341 acres before firefighters stopped its forward march Sunday night. The blaze, which broke out in Marin County, spread into rural ranchland as crews scrambled to keep it from advancing further.
The Marin County Fire Department said the fire began at about 4:40 p.m. Sunday near Chileno Valley Road, roughly four miles south of Tomales Road, according to CBS News. What started as multiple spot fires quickly drew a large mutual-aid response, with the outlet reporting that Marin County Fire, Gold Ridge Fire, Petaluma Fire, the California Highway Patrol, and CAL FIRE all converged on the scene. By the time crews got a handle on it, the fire had been mapped at 341 acres with just 5% containment as of Sunday night.
The fire was mapped at 341 acres by Sunday evening. Firefighters ultimately stopped the forward progress of all active spot fires along Chileno Valley Road by Sunday evening, according to fire incident updates relayed by SFGATE. No mandatory evacuations had been issued as of the CBS News report, though Zonehaven placed zone MRN-E118 in Chileno Valley under an evacuation advisory.
Mutual Aid Scrambles With Dozers and Air Tankers
The scale of the response reflected how quickly the fire spread. Emergency responders worked to knock down the multiple spot fires.
The cause of the Chileno Fire has not been determined, CBS News reported, and it remains under investigation by the Marin County Fire Department.
Smoke Advisories Stretch Across Four Counties
Even with the fire's spread halted, its smoke plume pushed the story beyond Marin County's borders. The Bay Area Air Quality Management District issued a North Bay air quality advisory through Monday for Sonoma and Marin counties, with the possibility it could expand to other counties, as reported by Local News Matters. Public health officials in neighboring Sonoma County issued their own advisory Sunday, warning downwind residents that air quality could reach unhealthy levels.
A Landscape Built for Grass Fires
Chileno Valley Ranch, west of Petaluma, is a 586-acre agricultural property with livestock operations protected by an agricultural conservation easement, according to the Marin Agricultural Land Trust. Those open grassland tracts, while central to the region's ranching heritage, also make the corridor prone to fast-moving late-summer wildfires. Hoodline reported on a similar hazard last month, when crews stopped a fire racing toward a solar farm near Highway 101 in Petaluma.
