Hillsborough: every big tree is protected, removals go to a hearing, and disputes resolve on hazard and specification

What the Town protects (HMC Chapter 14.04)

• 18 inches cumulative DBH, any species, measured at 54 inches above natural grade, multi-trunk diameters added.
• Any size: street trees, Town-designated heritage trees, trees required by a development approval.
• Permit: required for removal; arborist report on the Town template by an ISA Certified Arborist or ASCA consulting arborist.
• Hearing: non-hazard removals before the ADRB at a noticed public hearing; hazard removals at staff level with a certified arborist's written opinion and Town-arborist verification.
• Pruning: no percentage rule; pruning or damage a Town-qualified arborist decides would permanently compromise the tree is treated as removal. Routine structural pruning to ISA A300 is normally not.
• Penalty: $150 per inch of trunk diameter or the ISA-appraised value, whichever is greater; misdemeanor; 36-inch box replacement within six months (14.04.060).

Full permit rules and the Town template →

Why this changes a neighbor dispute

1. Removal is a public process. A neighbor who wants a tree gone has to persuade either the owner to apply and the ADRB to approve at a hearing, or establish a hazard. A complaint about leaves, roots or shade is neither.
2. The hazard track is the lever. A documented hazard, with a certified arborist's written opinion that removal is needed within 30 days, moves the case to staff level and out of the hearing. That opinion is exactly what a neighbor's independent report can establish, or rule out.
3. Self-help carries Town risk. With no percentage allowance, a cut on your side that a Town arborist later judges to have compromised the tree is "removal" at $150 an inch, on top of Booska liability. A written specification is the protection.
4. Appraised value is the penalty floor. Hillsborough trees are large and the ISA-appraised value of a mature oak or redwood is substantial, which is also what Civil Code 3346 doubles if a neighbor cuts yours.

What disputes look like here

Large lots with large trees: coast live oaks, valley oaks, redwoods, Monterey pines and cypresses, eucalyptus windrows, many of them planted a century ago. The common calls are hazard (Monterey pines and cypresses past their lifespan over neighboring roofs), roots under pool decks and driveways, and limbs over a neighbor's structure after a storm. Shared driveways and boundary trees on old estate subdivisions are a Hillsborough specialty.

What the report does in Hillsborough

1. Confirms ownership and that the tree is protected.
2. Assesses hazard in plain professional terms, and where a hazard exists, supports the owner's staff-level hazard application through a UFG permit report on the Town template.
3. Traces encroachment and states cause of any damage.
4. Writes a pruning or root specification to ISA A300 that stays below what the Town would treat as removal.
5. Cites the Civil Code and HMC 14.04.

Dispute Assessment Report, from $850. Start the report

Sources

1. Hillsborough Municipal Code Title 14, Chapter 14.04 (Ord. 789, eff. July 1, 2023), via Urban Forestry Guide, Hillsborough tree permit (verified July 31, 2026; fees checked October 9, 2026).
2. Town of Hillsborough Building & Planning, (650) 375-7411.