Sonoma-Marin Tree Service connects property owners with local arborists and CSLB-licensed local tree service contractors who inspect trees and explain the risk in plain terms. A good assessment often saves a tree that only needs pruning, and it gives you a record when a tree really does need to come down.
What a tree risk assessment is
A tree risk assessment looks at three things: the chance that a tree or part of it will fail, the chance that it hits something (a house, a car, a path people use), and how serious that would be. The result is a risk rating and a set of recommendations, such as removing a dead limb, reducing a heavy end, installing cables, monitoring, or removal.
The three levels of assessment
The industry standard for tree risk assessment (ANSI A300 Part 9, with ISA's Best Management Practices) describes three levels. They are not grades of quality; they are degrees of detail matched to the job.
- Level 1, limited visual: a quick look from one vantage point, on foot or from a vehicle, for obvious defects. It is mostly used for screening many trees, such as along a road or across a large property.
- Level 2, basic: a ground-based, 360-degree visual inspection of the tree and its site, often with simple tools like a mallet, probe, or binoculars. This is the level most homeowners get.
- Level 3, advanced: adds specialized methods, such as resistance drilling, sonic testing, or pull testing, to answer a specific question that a basic assessment cannot.
Ask which level is included before you hire anyone. A basic assessment answers most questions. An advanced one is worth paying for when a valuable or protected tree is in question and the visible signs are not enough.
The TRAQ credential
The International Society of Arboriculture offers the Tree Risk Assessment Qualification (TRAQ). It covers limited-visual and basic assessment and the principles of advanced techniques, and it ends with written and performance-based assessments. Candidates generally need a prerequisite such as ISA Certified Arborist, and ISA requires holders to retrain and retest every five years. TRAQ is a professional qualification, not a contractor license. You can ask an arborist for their ISA credential number and check it with ISA.
What the report says
A written assessment usually covers:
- The tree's species, size, location, and overall condition
- Defects found, such as decay, cracks, weak unions, root damage, or lean
- What is in the target zone and how often it is occupied
- A risk rating for each concern, and the time frame it applies to
- Recommended mitigation and the residual risk after that work
- When to re-inspect
When to get an assessment
- Before storm season. Late summer and fall give time to prune or remove before saturated soil and wind arrive. See storm-damaged tree removal for what happens when it is too late.
- After a storm, when a tree has a new lean, a split, or broken limbs hung up in the canopy.
- After construction near a tree. Trenching, grading, and paving inside the root zone can kill roots, and the decline often shows up years later.
- Before buying or selling a property with large trees close to the house.
- When a permit is needed for a protected tree. Towns such as Santa Rosa, Larkspur, and Mill Valley have heritage or protected tree rules, and an arborist report is often part of the application.
- When a neighbor is worried about your tree, or you are worried about theirs.
Local trees that often need a closer look
Coast live oaks and tanoaks in areas with Sudden Oak Death, old eucalyptus with heavy limbs, multi-stem redwoods with tight unions, and Monterey pines and cypress near the end of their lifespan are frequent subjects in San Rafael, Sebastopol, and across both counties. Trees on cut slopes and above retaining walls deserve extra attention, because the root plate is often compromised.
Worried about a leaning or cracked tree? Call (707) 634-8593 or request an estimate and we'll connect you with a local arborist or tree service contractor.
Tree services in Sonoma County & Marin County
- Tree Removal → Removal of dead, leaning, diseased, and unwanted trees, including large oaks, redwoods, and eucalyptus on tight or sloped lots.
- Storm-Damaged & Fallen Tree Removal → Fallen trees, split trunks, hanging limbs, and trees on roofs, fences, or driveways after North Bay winter storms.
- Tree Trimming & Pruning → Crown thinning, deadwood removal, structural pruning, and clearance pruning for oaks, redwoods, and ornamentals.
- Stump Grinding & Removal → Grinding stumps and surface roots below grade so you can replant, lay lawn, or build, plus full stump removal where needed.
- Arborist Reports & Tree Permits → Arborist reports for city and county tree removal permits, protected and heritage trees, and construction near trees.
- Defensible Space & Fire Clearance → Limbing up, juniper and brush removal, dead tree removal, and chipping for Marin evaluations and Sonoma inspections.
- Oak Tree Removal & Sudden Oak Death → Dead and dying coast live oaks, tanoaks, and valley oaks, including Sudden Oak Death losses and protected-oak permits.
- Eucalyptus Tree Removal → Taking down tall, brittle blue gum eucalyptus near homes, roads, and fire zones, and dealing with regrowth.
- Redwood Tree Removal & Trimming → Redwoods crowding foundations, driveways, and sewer lines, thinning redwood groves, and removals where a permit allows.
- Crane Tree Removal → Crane-assisted removals for big trees over houses, on steep hillside lots, and anywhere there is no room to drop or rig.
- Dead & Hazardous Tree Removal → Dead, dying, cracked, and leaning trees that threaten the house, the street, or the neighbors, with the paperwork hazard removals need.
- Roof Clearance & Limb Removal → Lifting limbs off roofs, gutters, chimneys, and decks for fire clearance, insurance letters, and plain peace of mind.
- Tree Risk Assessment → A qualified look at a leaning, cracked, or hollow tree before a storm decides for you, with a written recommendation.
- Lot Clearing & Brush Chipping → Clearing overgrown lots, thinning small trees and brush, and chipping or hauling the debris for building, fire safety, or sale.
- Fruit Tree & Olive Pruning → Dormant and summer pruning for backyard orchards, old olives, and heritage fruit trees on wine country properties.
- Palm Tree Trimming & Removal → Skinning and trimming tall palms, removing dead fronds and seed pods, and taking out palms that have outgrown the lot.
- Tree Cabling & Bracing → Support systems for split trunks and heavy limbs on trees worth keeping, installed and inspected to industry standards.
- Insurance-Required Tree Removal → Clearing trees and limbs an insurer has flagged before a policy renewal or non-renewal deadline, with documentation.
- View Pruning → Opening up bay, hill, and valley views with selective thinning and reduction that keeps the tree healthy and the neighbors on side.
Frequently asked questions
What is TRAQ?
TRAQ is the ISA Tree Risk Assessment Qualification, a credential from the International Society of Arboriculture. Holders have completed ISA training and assessments in limited-visual and basic tree risk assessment and the principles of advanced techniques. Candidates generally need a prerequisite credential first, such as ISA Certified Arborist, and ISA says the qualification must be renewed by retraining and retesting every five years.
Can an assessment tell me a tree will not fall?
No. Any tree can fail, especially in extreme wind. A risk assessment estimates how likely failure is, what it would hit, and how bad the consequences would be, then recommends ways to reduce that risk. It is a professional judgment, not a guarantee.
My tree is leaning. Is that dangerous?
Not necessarily. Many trees grow with a lean toward light and are stable. A lean that is new or getting worse, especially with cracked or heaving soil on the opposite side, can mean the roots are failing. That calls for a prompt look, and in the meantime keep people and cars out of the area it could hit.
Does a risk assessment count as an arborist report for a permit?
Sometimes. Many towns want a report from a certified or qualified arborist with a removal application, and a risk assessment can be part of it. Requirements vary by city, so ask the planning department what they need before you order the report.
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