An arborist report is a written finding about a tree or a group of trees: what species they are, what condition they are in, what is wrong if something is wrong, and what should happen next, set out so that someone who was not on site can rely on it. I prepare them as an independent consulting arborist, an ISA Board Certified Master Arborist with the Tree Risk Assessment Qualification, working out of Placerville across El Dorado, Sacramento, Placer, and Amador counties. Most of my reports go to a county reviewer, an HOA, an insurer, or a buyer, and most of them are about oaks, because oaks are what the El Dorado County Oak Resources Management Plan protects. I run no removal crews, so the report is the product and the recommendation is not attached to a job I would then perform.
What an arborist report is
The phrase covers a lot of ground, so it is worth being precise. At its simplest, an arborist report documents a tree the way a home inspection documents a house: species, size, condition, defects, and a recommendation, in writing, from someone qualified to judge. The difference between a report and a verbal opinion is that a report can be handed to a third party, checked against the tree, and relied on later, which is why counties, HOAs, insurers, and courts ask for one rather than a phone call.
The tree care a report recommends follows ANSI A300, the American National Standard for tree care operations, and the report itself is prepared to the International Society of Arboriculture's best management practices. That is what gives it weight with a reviewer. A report that cannot say what standard it was written to is an opinion with a letterhead.
What goes into one
Every report I write follows the same structure, because a reviewer should be able to find the same thing in the same place every time:
- Scope: which trees, on which parcel, at whose request, and what question the report is answering.
- Methods: how each tree was examined, what was measured, and whether anything went to the lab.
- Findings: species, diameter at breast height, height and spread where they matter, a condition rating, and any defects, decay, disease, or root damage observed, with photographs.
- Analysis: what the findings mean for the question asked, whether that is a permit threshold, a risk rating, a construction impact, or a diagnosis.
- Limitations: what the inspection could not establish, such as the extent of internal decay without resistance drilling, and what was not examined.
- Conclusion: a plain recommendation, and the conditions or mitigation it depends on.
- Sources: the standards, county documents, and published research behind the conclusions.
Where a permit is involved, the report also carries the specific measurements and map references the jurisdiction asks for, so the reviewer is not sending it back over a diameter taken at the wrong height.
Who asks for an arborist report, and why
The request usually comes from one of a handful of places, and knowing which one shapes what the report needs to contain.
- County planning and building staff, who need to know whether protected trees are affected by a grading or building permit and what mitigation applies.
- A CEQA lead agency, where tree impacts feed into the environmental review of a development project.
- An HOA or architectural committee deciding whether to approve a removal or a significant pruning.
- An insurer or adjuster who needs a documented condition, cause, or risk rating for a claim.
- A buyer, seller, or lender in a property transaction who wants the mature trees on the parcel understood before money changes hands.
- An attorney in a dispute over a tree, a boundary, a failure, or construction damage.
- A homeowner who has been quoted a removal and wants an independent answer on whether the tree actually needs to come down.
The last one is the most common call I get, and it is the one where an independent report pays for itself fastest.
Types of arborist reports I prepare
As a consulting arborist serving El Dorado County, California, I provide the following report types:
- Preconstruction arborist reports for El Dorado County, CA grading and building permits
- CEQA arborist reports and tree impact analysis for environmental review
- Oak Technical Reports and heritage tree reports in compliance with El Dorado County Oak Resources Management Plan
- Tree preservation plans for subdivisions and major remodels in El Dorado Hills, Placerville, and Cameron Park
- Hazard tree and risk assessment reports for HOA and insurance requirements
- Tree inventory reports for property transactions and estate planning
Two of these have pages of their own, because El Dorado County handles them as separate processes: the Oak Technical Report the county requires when a project affects protected native oaks, and the removal permit process for taking an oak down.
Most of the reports I write in this county are about oaks, because oaks are what the ordinance protects and what these parcels are covered in. Blue oak and interior live oak on the dry slopes, valley oak on the deeper soils, and California black oak through the middle elevations around Placerville, Camino, and Pollock Pines. Conifer work comes up as well, usually ponderosa pine, gray pine, and incense cedar, and usually tied to defensible space rather than to a permit.
When El Dorado County Requires an Arborist Report
In El Dorado County, an arborist report is typically required for:
- Oak tree removal permits under the El Dorado County Oak Resources Management Plan
- Grading permits and land development applications in El Dorado County
- Subdivision maps and major remodels in Placerville, El Dorado Hills, and Cameron Park
- CEQA environmental review for projects with potential tree impacts
- HOA tree removal or modification requests
- Insurance claims involving tree damage or removal
What an arborist report costs, and how long it takes
A site assessment with a written report starts at $500. The site visit on its own is $250 and covers up to one hour on site, without the written product. The $500 report covers a single property question: one tree or a small group, the inspection, the diagnosis or condition rating, photographs, and the written recommendation. Larger parcels, development surveys, and multi tree inventories are quoted before anything is scheduled, so there is no surprise on the invoice.
The report usually follows within a few business days of the site visit. Where a sample goes to the lab for culturing or microscopy, that adds time, and I say so up front. If a permit deadline is driving the schedule, tell me when you call and I will tell you honestly whether it can be met.
What makes an arborist report hold up
A reviewer, an adjuster, or opposing counsel will test a report on a few things. Whether the author's credential can be verified in a public register. Mine is ISA Board Certified Master Arborist WE-14385B, with the Tree Risk Assessment Qualification. Whether the methods are stated and the limitations are honest. Whether the measurements were taken the way the jurisdiction specifies. Whether the sources are cited. And whether the person who wrote it had a financial interest in the outcome.
That last one is why I do not run a removal crew. A report whose recommendation always seems to end in a chainsaw quote is worth noticing, and reviewers notice. The value of an independent report is that the tree, not the job, decides what it says.
Frequently Asked Questions
Do I need an Arborist Report?
Many municipalities require an arborist report before construction, to document the impact a project may have on the trees on a site. Reports are also used to protect notable or high value trees, because a thorough inspection each year catches problems while they are still manageable. If you are serious about keeping the trees in your landscape healthy, an arborist report from an ISA Certified Arborist is a good place to start.
Are there different types of Arborist Reports?
Yes. Beyond the standard arborist report, which documents a tree or a group of trees and their condition, there are tree risk assessments and tree preservation plans.
A tree risk assessment communicates the level of risk a tree poses to people and to the structures around it, as a documented rating rather than an impression.
Tree Preservation Plans are most often utilized as part of a construction plan to help preserve trees which are planned to be retained on the property. They can also be used for properties with mature high value trees which are important to maintain.
What counties do you serve?
I prepare arborist reports for El Dorado County, Sacramento County, Placer County, and Amador County. For the right project I will travel outside that area.
Is a free assessment the same as an arborist report?
Many tree trimming companies offer a free on site assessment, and often you get what you pay for. Some use it as a sales tool to push a removal. Plenty are neither uninformed nor unethical, but the quality depends entirely on who shows up. A free assessment is also usually a verbal opinion rather than a written record you can hand to a county reviewer, an insurer, or an attorney.
A consulting arborist writing an arborist report produces an unbiased assessment of your trees. Where a condition is unclear, the job is to investigate it and identify the causal agent rather than guess. The report then sets out recommendations for maintaining tree health, so problems get caught before removal becomes the only option left.
How much does an arborist report cost?
A site assessment with a written report starts at $500. The site visit on its own is $250 and covers up to one hour on site. That is a small amount next to the cost of the work it informs: a medium sized tree removal near a home can run $1,500 to $4,000, and an independent written assessment tells you whether that removal is actually necessary or whether the tree can be kept. You are paying for an informed recommendation, not a sales pitch.
What is an Arborist Report?
A written document from a qualified arborist that records species, size, condition, and defects, and gives a recommendation, prepared so that a county reviewer, an HOA, an insurer, or an attorney can rely on it. Mine are written to ISA best management practices, with tree care recommendations that follow ANSI A300, the American National Standard for tree care operations.
Do I need an arborist report to remove a tree?
It depends on the tree and where it stands. In El Dorado County, a native oak six inches or more in diameter, or a multi trunk oak whose three largest trunks total ten inches, on a parcel at or below 4,000 feet, generally needs a permit before it comes down, and the permit application needs an arborist report. Other jurisdictions protect different trees at different sizes. If you are not sure, a site visit settles it faster than a wrong guess, and a removal done before the permit can cost roughly three times what the permitted route would have.
How long is an arborist report valid?
There is no fixed expiry, but a report describes a tree on the day it was inspected. Most reviewers want a recent one, and for a permit application that often means within the last year. A tree that has been through a storm, a construction project, or a hard dry summer since the report was written may need a fresh look. If a report of mine needs updating for a deadline, call and I will tell you whether a re inspection is needed.
Can any arborist write an arborist report?
Anyone can write one. Whether it is accepted is another matter. County reviewers and CEQA lead agencies generally require a report from an ISA Certified Arborist, and many specify a consulting arborist or a Board Certified Master Arborist for development work. Risk ratings should come from someone holding the Tree Risk Assessment Qualification. Ask who will sign the report and check the credential in the ISA register before you pay for it.
Does an arborist report include the dollar value of a tree?
Not for insurance or litigation. I can appraise a tree, but I do not produce a dollar figure for a claim or a legal matter, and I refer that to a qualified appraiser. What the report gives you is species, condition, cause, and risk, documented well enough that an appraiser or an adjuster can build on it.
