I write arborist reports and tree protection plans for 45 Bay Area cities, and most of the confusion I see starts with a word. The same tree is a "heritage tree" in one city, a "significant tree" next door and an "ordinance-size tree" across the county line. This page defines the terms as the codes use them. Where a definition depends on the city, it says so and links to the table that has every city's rule.
Measuring the tree
- DBH (diameter at breast height)
- Trunk diameter measured at a fixed height above natural grade. Most Bay Area cities measure at 54 inches above grade, which is 4.5 feet. Berkeley, Campbell, Los Altos and Woodside measure at 48 inches above grade, and Tiburon at 24. Many codes use circumference instead, so check how your city measures before you reach for a tape.
- Circumference
- The distance around the trunk at the measurement height, taken with a taut tape. Divide by 3.14 to get the diameter: a 38-inch circumference is about 12 inches in diameter. San Jose, Redwood City, Sunnyvale and Menlo Park write their thresholds in circumference. Most other cities use diameter, and a few print both.
- Measurement height
- The point above natural grade where the trunk is measured. It matters because a trunk is narrower at 54 inches above grade than at 24. Thirty-five of the 45 cities measure 54 inches above grade, five at 48, Tiburon at 24, and Redwood City at the widest point between 6 and 36 inches above ground.
- Multi-trunk rule
- How a city measures a tree with several stems. Cupertino adds all trunks and protects the sum at 24 inches, against 12 inches for a single trunk. Santa Clara measures a multibranched tree below the first fork. Woodside sums the trunks of madrone, blue oak and buckeye but counts only the largest trunk of a bay laurel.
Categories of protected trees
- Protected tree
- Any tree a city's ordinance covers, so that removing it needs a permit. Each city defines it by species, size or both. Oakland protects coast live oaks from 4 inches DBH and other species from 9 inches. Palo Alto protects listed natives at 11.5 inches DBH, most other species at 15 inches DBH and redwoods at 18 inches DBH.
- Heritage tree
- A protected tree given a higher tier by species, size or formal designation. Menlo Park's heritage tree is any species at 47.1 inches circumference, or an oak at 31.4 inches, measured at 54 inches above natural grade. Palo Alto heritage trees are designated by City Council at any size. The tier usually brings a higher fee and a steeper penalty.
- Significant tree
- Another name some cities use for a protected tree, with its own size table. Woodside's significant trees start at 24, 30 or 36 inches circumference by species, measured at 48 inches above grade. San Francisco's significant tree stands within 10 feet of the public right-of-way and is over 12 inches DBH, 20 feet tall or 15 feet in canopy.
- Ordinance-size tree
- San Jose's term for a private tree large enough to need a removal permit: 38 inches circumference measured at 54 inches above natural grade, any species. Other cities use protected, heritage or significant for the same idea. The term matters because San Jose's permit fee for a live ordinance-size tree is far higher than for a dead one.
- Street tree
- A tree in the public right-of-way, usually the strip between sidewalk and curb, even when you water it. Street trees are permitted separately from private trees, often through Public Works, and in some cities carry their own penalties. Piedmont and San Rafael regulate only public trees and have no private-tree removal permit at all.
Documents the city asks for
- Arborist report
- A signed written report by a certified arborist giving species, measurements taken the city's way, condition, photographs, the reason for removal in the code's terms and usually a replacement plan. Sixteen of the 45 cities require one with every removal application and 23 ask in specific situations. See the requirements by city and what one costs.
- Tree protection plan (TPP)
- A document and plan-set exhibit showing how protected trees will survive construction: the protection zone, fencing and signage, grading and trenching rules, and a monitoring schedule. Several cities require it as a condition of building permits for remodels and new construction. Some cities title it a tree preservation plan; it is the same document.
- Tree protection zone (TPZ)
- The area around a tree fenced off during construction, where grading, trenching, storage and parking are not allowed. Cities define its size differently, and several codify a radius of 10 times the trunk diameter. Work inside the zone is what triggers the tree protection plan in most codes, so the zone is drawn to the city's definition.
- Critical root zone
- The part of the root system a tree needs to stay alive and upright. It sits near the surface and can extend past the canopy edge. Arborists size it from trunk diameter, not from the dripline. The city's tree protection zone is the regulatory version; the critical root zone is the biological one, and the two do not always match.
- TRAQ
- The ISA Tree Risk Assessment Qualification, a credential for arborists who assess tree risk by the ISA method: likelihood of failure, likelihood of impact and consequences, combined into a rating for a stated time frame. Palo Alto's department page says a hazard claim in a permit application needs a Level 2 TRAQ assessment.
- Level 1, 2 and 3 assessment
- The three levels of tree risk assessment in the ISA method. Level 1 is a limited visual check used to screen many trees. Level 2 is a basic assessment: a ground inspection of the whole tree with a written rating. Level 3 is advanced: resistance drilling, sonic tomography or climbing inspection when Level 2 leaves a question open.
Value, fees and replacement
- CTLA trunk formula
- A method from the Council of Tree and Landscape Appraisers' Guide for Plant Appraisal. It values a tree too large to buy by starting with the cost of the largest available nursery tree, scaling by trunk area, then adjusting for species, condition and location. Palo Alto, Los Altos, Campbell and Danville tie their penalties to CTLA-appraised value.
- Appraised value
- The dollar value an arborist assigns to a tree, usually by the CTLA trunk formula or by the cost to replace it. Many Bay Area penalties are a multiple of it. Atherton charges twice the appraised value for an unpermitted removal and Danville three times. Menlo Park charges up to $5,000 per tree or the tree's value, whichever is higher.
- In-lieu fee
- A payment to the city's tree fund instead of planting the replacement trees a permit requires, used when the lot has no room for them. Palo Alto's 2026 in-lieu fee is $1,250 per 24-inch box tree. Belmont charges $611 per tree, Los Altos $1,258.29, San Francisco $2,646 per tree and Burlingame $325 per inch of trunk diameter.
- Replacement ratio
- How many trees you must plant for each one removed, and at what container size. Mountain View's standard is 2:1 or an in-lieu payment. San Jose requires 1:1 on a single-family lot, 15-gallon minimum, with a 24-inch box counting as 2 credits. For unpermitted removals Orinda requires two 24-inch box trees per 6 inches of removed trunk diameter.
Exceptions and process
- Dead or hazardous tree exemption
- A rule that lets a dead or dangerous tree skip part of the permit process. Mountain View exempts dead trees once the City Arborist confirms the condition. Palo Alto, Oakland and Redwood City still require a permit for a dead but stable tree; the dead condition is the ground for approval, not an exemption. Every city's rule.
- Emergency removal
- Removing an immediate threat before a permit is issued, allowed only on the conditions the code names. Redwood City lets you remove and then contact the City Arborist within 72 hours. Oakland requires a report by the next business day. Pleasant Hill requires the permit application within five days. Photograph the tree before anyone cuts.
- Permit vs no-fee notification
- A permit is a written approval you must hold before work starts. Some cities handle dead trees with a staff determination instead. Pleasant Hill's Zoning Administrator can find a tree dead with no permit and no fee, and Orinda issues an emergency tree removal letter at no charge. Redwood City and Fremont keep the permit but charge nothing.
Who writes the report
- ISA Certified Arborist
- A credential from the International Society of Arboriculture, earned by exam and experience and kept current with continuing education. Most Bay Area codes that require an arborist report name this credential, often alongside ASCA membership. Hillsborough, Los Altos and Campbell define certified arborist as ISA or ASCA. My certification number is WE-15750A.
- Certified Urban Forest Professional
- A credential for arborists whose work covers the urban forest as a system rather than one tree at a time: canopy, planting programs, ordinances and long-term management. It sits alongside the ISA Certified Arborist credential, which is tree-level. I hold both; the urban forest credential is WE-15750AF. More on the author page.
- Consulting arborist vs tree service
- A consulting arborist assesses, writes and testifies, and does not sell tree work, so the recommendation has nothing riding on it. A tree service prunes and removes trees. Cities accept a report from either if the signer holds the certification the code names, but a quote is not a report. Full comparison, or a second opinion on a quote.
Still not sure what your city calls your tree? The Permit Checker applies the city's definition to your species and trunk size, and each city permit page quotes the code.
Michael Schuck
ISA Certified Arborist WE-15750A · Certified Urban Forest Professional WE-15750AF
About the author
ISA Certified Arborist WE-15750A · Certified Urban Forest Professional WE-15750AF
About the author