What Is an Arborist Report?

An arborist report is a formal, written evaluation of a tree or group of trees prepared by a qualified tree care professional—usually an ISA Certified Arborist. These reports are designed to assess and document a tree’s species, health, structural integrity, and proximity to development, structures, or utilities.

Arborist reports are often required by municipalities for regulatory compliance, particularly when trees are subject to removal, construction activity, or preservation obligations under city ordinances. The report helps city planners, developers, homeowners, and contractors make informed decisions about how to proceed while balancing tree health and safety with practical land use needs.

Why Are Arborist Reports Important?

An arborist report is more than just a formality. It ensures that decisions about trees are based on facts—not assumptions. This has several key benefits:

• Risk Management: Identifies trees that may pose a hazard due to decay, structural defects, or proximity to people and property.

• Permit Approval: Most cities require arborist documentation for tree removal or construction projects involving protected species.

• Tree Preservation: Helps guide site planning to protect valuable trees during grading, trenching, or building work.

• Environmental Compliance: Supports sustainability goals and helps ensure compliance with local environmental policies.

• Legal Protection: A well-documented report can serve as a defensible record in the event of disputes, damage claims, or regulatory challenges.

In short, arborist reports provide transparency, reduce liability, and promote better long-term outcomes for trees and properties alike.

When Is an Arborist Report Required?

While every jurisdiction has different rules, arborist reports are typically required in the following situations:

1. Tree Removal Applications

If you're planning to remove a tree—particularly one classified as heritage, native, or protected—you’ll likely need an arborist report to justify removal. The report documents the tree’s condition and explains why it should be removed, whether due to disease, structural failure, interference with infrastructure, or development constraints.

2. Construction and Development Projects

When trees are located near proposed construction, cities often require a tree protection plan or impact assessment. This ensures trees are preserved during work such as:

• Foundation or retaining wall installation

• Utility trenching

• Grading and excavation

• Driveway or sidewalk construction

Arborist reports outline how trees will be protected during the project and provide guidelines to avoid damage to roots, trunks, and canopies.

3. Hazardous Tree Evaluation

When a tree leans suddenly, shows signs of decay, drops large limbs, or grows close to buildings or power lines, an arborist report can help determine whether it poses a risk. If removal or mitigation is necessary, the report offers expert justification and recommended next steps.

4. Permit Compliance or Dispute Resolution

In cases involving neighborhood disputes, property development reviews, or insurance concerns, an arborist report provides an unbiased, science-based perspective. It can also help satisfy requirements under CEQA (California Environmental Quality Act) for larger developments.

Common Types of Arborist Reports

Depending on your specific situation, your arborist may recommend one of the following report types:

• Tree Risk Assessment

Assesses the likelihood of a tree or branch failure and the potential consequences. Risk ratings (Low, Moderate, High, or Extreme) help guide recommendations for pruning, monitoring, or removal.

• Tree Removal Justification

Used to support removal permit applications. This report documents structural defects, poor health, site constraints, or safety issues that warrant removal.

• Tree Protection Plan

Developed for construction sites, this report outlines specific measures to preserve trees during excavation, grading, and development. It may include protective fencing zones, prohibited activity areas, and monitoring requirements.

• Health and Condition Assessment

Focuses on diagnosing pest or disease problems, nutrient deficiencies, root issues, or decline. It provides treatment recommendations and expected prognosis.

• Tree Inventory Report

Used for large parcels or commercial developments, this report catalogs all trees by species, size, condition, and value. It helps developers, architects, and planners make informed land-use decisions.

What’s Included in an Arborist Report?

While each report is tailored to its purpose, most arborist reports include the following elements:

• Tree identification (species, size, age, and location)

• Health and structural assessment (visual inspection for decay, cavities, pests, cankers, etc.)

• Photos and site documentation

• Proximity to existing or proposed structures

• Construction impact evaluation (if applicable)

• Tree Protection Zone (TPZ) calculations

• Tree risk ratings, using standardized assessment methods such as ISA TRAQ

• Recommendations (removal, retention, pruning, monitoring, or treatment)

• Maps or diagrams, often overlaid on site plans

• Mitigation guidelines, including replanting or preservation measures

In some cases, the report may also include tree appraisals to determine monetary value based on size, species, and condition—useful in damage claims or legal cases.

Who Can Write an Arborist Report?

Not just anyone can prepare an arborist report that will be accepted by a city or regulatory agency.

✔ Certified Arborists

Most cities require the report to be prepared by an ISA Certified Arborist (International Society of Arboriculture). These professionals have undergone extensive training and examination in tree biology, risk assessment, and industry standards.

✔ TRAQ-Certified Professionals

For risk-related reports, municipalities often require arborists to hold a Tree Risk Assessment Qualification (TRAQ). This credential demonstrates expertise in evaluating and communicating tree risk using industry protocols.

✔ Registered Consulting Arborists

Some jurisdictions accept or even require reports from Registered Consulting Arborists (RCA)—professionals certified by the American Society of Consulting Arborists (ASCA). These arborists specialize in complex assessments, expert witness work, and municipal consulting.

✔ Approved Arborist Lists

Certain cities maintain a list of pre-approved consulting arborists, and only those listed individuals may submit reports for permitting. It’s essential to confirm with your local planning department whether a specific arborist is qualified to meet their requirements.

Tips for Working with an Arborist

To get the most value out of your arborist report:

• Start early: Don’t wait until the last minute before submitting a permit or site plan. Arborist reports can take time to schedule, inspect, and prepare.

• Choose local expertise: An arborist familiar with your municipality’s tree ordinances will be better equipped to provide a compliant and effective report.

• Be transparent: Share all relevant site plans, development goals, or concerns upfront. The more information your arborist has, the more accurate the recommendations will be.

• Plan for follow-up: Some cities may require additional monitoring or reports during construction. Ongoing communication with your arborist can help ensure compliance.

Conclusion: Why Arborist Reports Matter

Whether you're a homeowner looking to remove a dead tree or a developer navigating a large construction project, an arborist report is your roadmap to responsible tree management. It balances safety, legal compliance, and environmental stewardship—all while protecting your investment.

In today’s regulatory environment, working with a qualified arborist isn’t just good practice—it’s often a requirement. A clear, well-prepared arborist report streamlines approvals, supports good design, and demonstrates your commitment to tree care and urban sustainability.

Need a Professional Arborist Report?

At NewVista Tree Service, our ISA Certified Arborists prepare detailed, city-compliant reports tailored to your unique project. Whether you need a tree risk assessment, removal justification, or construction protection plan, we provide expert guidance every step of the way.

We work closely with contractors, homeowners, architects, and planners to ensure your report meets city requirements and helps you move forward with confidence.

Book Online to schedule your consultation and get your project on the right track.