Mill Valley's network of ridgeline and shaded fuel breaks slowed the spread of the Hillside Avenue fire on Monday, July 27, and bought firefighters enough time to contain the 1.5-acre blaze before it reached homes, Interim Fire Chief Tom Welch said in a post-incident message Wednesday, July 29.

"The strategic fuel break in this area held the fire in check until fire crews and aircraft could arrive, giving our firefighters a fighting chance when confronting wildfire in the steep canyons and treasured ridgelines that define our area," Welch wrote.

As we reported July 28, the fire broke out at 4:42 p.m. Monday, July 27, in the 300 block of Hillside Avenue, north of East Blithedale Avenue and just south of Mayor's Lookout. A PG&E-funded helicopter arrived first with water drops, followed by CalFire air tankers. Crews halted the fire's forward progress by approximately 6:24 p.m. No one was injured and no structures were damaged.

The fire burned through previously treated vegetation, which the district said contributed to its slow rate of spread.

$1.16 million invested so far

Welch and Fire Marshal Fred Hilliard credited the Greater Mill Valley Shaded Fuel Break project, which began in 2025. According to the chief's message, more than 35% of the project is complete, with approximately $1,163,000 invested to date from Measure C and the Mill Valley Municipal Services Tax.

The broader Greater Mill Valley Fuel Break covers 673 acres and targets an 11-to-13-mile continuous treatment corridor around the city. Work planned for 2026-2027 is expected to bring the running total to between 7.57 and 8.57 miles, according to the Mill Valley Briefing, putting the project close to 70% of the linear treatment needed to fully encircle Mill Valley.

Measure C, the countywide Marin Wildfire Prevention Authority parcel tax approved by voters in March 2020 with 70.8% support, generates more than $22 million annually and sunsets in August 2029. A grant from the California Coastal Conservancy also helped fund the vegetation work.

Neighborhood meeting planned

The Southern Marin Fire Protection District, in partnership with the City of Mill Valley, the Mill Valley Police Department, and other agencies, is planning a regional neighborhood meeting to share findings from the fire investigation, answer questions, and reinforce emergency-preparedness resources. No date has been announced.

Welch called the fire a return on the community's investment in wildfire prevention.

The cause of the fire remains under investigation. The Hillside Avenue blaze came less than two weeks after PG&E shut off power to more than 2,000 meters in the Mill Valley area on Wednesday, July 15, as a wildfire safety measure during hot, dry, and windy conditions.

Residents can register for AlertMarin emergency alerts and are encouraged to prepare go-bags and identify at least two evacuation routes from their homes. The district said it will announce the neighborhood meeting date through its regular channels.