Hillsborough Fire Hazard Reduction Projects

Beginning in 2013, the Town of Hillsborough's Open Space Vegetation Management Project created defensible space zones between town-owned open space and neighboring homes, one of the more ambitious municipal fuel reduction efforts in San Mateo County at the time.

Background

Hillsborough owns nine open space areas within its incorporated limits, ranging from about 1.6 to 54 acres and totaling roughly 240 acres of undeveloped, steep, heavily vegetated terrain. A wildland-urban interface exists wherever these open spaces border residential properties.

The town built its program deliberately: a vegetation and biological survey in 2006 established baseline data on plant communities, sensitive species habitat, and fuel loads; a Vegetation Management Strategies and Guidelines report followed in 2008; and in 2009 the Town Council approved a task force priority list with wildfire management at the top. The project complied with CEQA and NEPA and with state and federal Endangered Species Act requirements under an adopted Initial Study/Mitigated Negative Declaration.

The Work

Fuel reduction covered approximately 88 acres in two treatment types across eight open space areas, with work "field fit" to avoid creeks and sensitive species habitat:

• Defensible Space Zones (about 42 acres): the most intensive treatment, adjacent to homes. Crews removed roughly one third to one half of understory vegetation, eliminated ladder fuels, and hauled green waste off site. CAL FIRE hand crews created about 20 acres of defensible space zones in the initial phase.
• High Priority Fire Management Areas (about 46 acres): a lighter treatment removing roughly one quarter to one third of understory vegetation and reducing ladder fuels, with green waste treated on site to speed decomposition and discourage ignition.

Native shrubs and trees were retained where possible. No large live trees were removed; some saplings under 4 inches diameter were thinned to open dense stands, and dead or diseased trees were felled.

Maintenance

Initial clearing was followed by two years of maintenance in both treatment types, holding fuel loads down and controlling invasive plants, French broom, pampas grass, and blackwood acacia among them, that recolonize treated ground. That maintenance requirement is the standard lesson of fuel work everywhere: treatment is an ongoing commitment, not a one-time project. See how fuel breaks work and our other completed projects.