Grove Tree Care · Tree Care Blog · Portland South Metro
A tree health assessment is an on-site evaluation by an ISA-certified arborist that tells you the condition of your tree — what’s wrong, why, and what your options are. Most homeowners need one when a tree looks sick or stressed, after storm damage, before a major landscaping project, or when a city permit requires an arborist report. Free estimates from a tree company are not the same thing — a health assessment is a diagnostic service, not a sales call.
What Happens During a Tree Health Assessment
A tree health assessment is a systematic, science-based evaluation of your tree’s overall condition. An ISA-certified arborist examines the tree from multiple angles — above ground and, where possible, at the root zone — and evaluates several key factors:
Canopy condition — leaf color, density, premature drop, dieback in the upper crown, and signs of stress or disease in the foliage.
Bark and trunk — cracks, splits, cankers, fungal growth, areas of missing or peeling bark, signs of pest infestation (exit holes, frass, galleries), and wet or discolored patches indicating bacterial infection.
Branch structure — co-dominant stems, overextended limbs, weakly attached branch unions, previous topping or poor pruning cuts, and dead or hanging branches.
Root zone — soil compaction, grade changes, root damage from construction or utilities, surface roots showing distress, fungal growth at the base, and signs of root rot.
Environmental factors — site conditions, drainage, proximity to structures or utilities, recent construction impact, and soil conditions specific to your property.
After the evaluation, the arborist gives you a clear summary of findings and specific recommendations — whether that’s treatment, pruning, cabling, monitoring, or removal. A written arborist report documents the findings formally when one is required for a permit or legal purpose.
A Free Estimate Is Not a Tree Health Assessment
This is worth clarifying because the two get confused regularly.
When you call a tree company for a free estimate, you’re getting a quote for a specific job — usually removal or pruning. The estimator looks at access, crew requirements, and scope. It’s a pricing exercise, not a diagnostic one.
A tree health assessment is different. An ISA-certified arborist evaluates the tree’s condition with the goal of understanding what’s happening biologically and structurally — and giving you options. That might mean recommending removal, treatment, cabling, or simply monitoring. It might mean telling you the tree is fine and you don’t need to spend any money.
At Grove Tree Care, our free on-site estimates include an honest assessment of what we observe. But when a property transaction, permit application, or legal dispute requires a formal written arborist report, that’s a separate, documented service.
When You Need a Tree Health Assessment in the Portland South Metro
You probably need one if:
- A tree on your property looks sick, stressed, or declining and you don’t know why
- A tree failed to leaf out in spring, or is dropping leaves significantly earlier than surrounding trees
- You’ve noticed mushrooms, fungal growth, or soft wood at the base of a tree
- A tree developed a new lean or you’ve noticed soil heaving around the base
- A tree sustained storm damage and you’re not sure if it’s structurally sound
- You’re buying or selling a property with significant trees and want an independent evaluation
- Your city requires an ISA arborist report as part of a permit application
- You’re planning construction near trees and need a pre-construction assessment
- An HOA or neighbor dispute involves the condition or value of a tree
You probably don’t need one if:
- You already know the tree needs to come down and just need a removal quote
- The issue is clearly cosmetic — a branch you want removed for aesthetics
- The tree is visibly dead — a simple estimate covers what you need
Honest advice is part of what we do. If you call us and your situation doesn’t warrant a formal assessment, we’ll tell you that too.
When Portland South Metro Cities Require an ISA Arborist Report
Several cities in our service area require a formal ISA arborist report as part of the permit process — making a tree health assessment not just useful but legally necessary:
Lake Oswego — Type II permit applications for elective removal of native trees typically require an ISA arborist report addressing the tree’s condition and removal criteria.
Sherwood — Street trees over 10″ DBH require an ISA arborist report addressing the tree’s condition and specific removal criteria before a permit is issued.
West Linn — Heritage tree removal applications require documentation from a certified arborist. Complex removal situations may also require formal assessment.
Wilsonville — Type B permit applications for removal in the SROZ (Significant Resource Overlay Zone) may require arborist documentation depending on the tree and location.
Oregon City — Significant tree removal under the Development Code may require arborist documentation for permit approval.
Our ISA-certified arborists prepare reports that are specifically structured to address each city’s permit criteria — giving your application the strongest possible foundation. For a complete city-by-city permit guide, read our tree removal permit guide for the Portland south metro.
What's in a Written Arborist Report
When a formal written report is required — for a permit, property transaction, or legal matter — it typically includes:
- Tree species, location, and size (DBH, height, canopy spread)
- Overall health rating and condition assessment
- Identified defects, disease, or structural issues
- Risk evaluation — likelihood and consequence of failure
- Specific findings that address permit criteria or the question at hand
- Recommended management actions — with timeline and priority
- Arborist’s ISA certification number and signature
Written reports prepared by Grove Tree Care’s ISA-certified arborists are accepted by planning departments across the Portland south metro including West Linn, Tualatin, Wilsonville, Lake Oswego, Sherwood, and Oregon City.
Tree Health Assessments and Property Transactions
Real estate transactions involving properties with significant trees increasingly involve arborist assessments — particularly in West Linn, Lake Oswego, and Wilsonville where heritage trees and permit requirements can affect what can and can’t be done with trees on the property.
A pre-purchase assessment can reveal:
- Trees that appear healthy but have significant internal decay or root problems
- Heritage or significant tree designations that restrict removal options
- Trees that are likely to require expensive removal or treatment in the near future
- Trees with structural issues that may create liability
For sellers, an assessment before listing can prevent surprises during inspection and document the condition of significant trees clearly.
How to Schedule a Tree Health Assessment in the Portland South Metro
The process is straightforward:
- Call or request online — describe what you’re seeing and what you need the assessment for (general health, permit application, property transaction, etc.)
- On-site visit — an ISA-certified arborist visits your property, evaluates the tree, and gives you an honest summary of findings
- Written report — if required for a permit, transaction, or legal purpose, we prepare a formal written arborist report documenting the findings
- Recommendations — we explain your options clearly, including if no action is needed
We serve West Linn, Tualatin, Wilsonville, Lake Oswego, Sherwood, Oregon City, Beaverton, Canby, Aurora, and the surrounding Portland south metro from our shop in Aurora, OR.
For a sense of what tree work costs if the assessment leads to a recommendation for removal, see our 2026 tree removal cost guide for the Portland metro area.
Schedule Your Free Tree Health Assessment
If you have a tree you’re concerned about, the best next step is a free on-site assessment from one of Grove Tree Care’s ISA-certified arborists. We’ll evaluate what we observe, give you honest options, and let you know if a formal written report is warranted for your situation.
- ISA Certified Arborists on every assessment
- Oregon LCB License #100543
- Written arborist reports for permit applications
- Accepted by all south metro planning departments
- Free on-site assessments — no obligation
- 24/7 emergency response for hazardous situations
Written by the team at Grove Tree Care — ISA-certified arborists serving West Linn, Tualatin, Wilsonville, Oregon City, Sherwood, Lake Oswego, and the Portland south metro from our Aurora, OR shop.