Hazard Trees, High-Risk Trees, and Imminent Hazards
These terms are often used interchangeably, but they do not mean exactly the same thing.
A tree may have defects such as decay, cavities, root damage, severe lean, weak branch attachments, or previous failures without presenting an immediate emergency. A qualified arborist can perform a
tree risk assessment to evaluate the likelihood of failure, what could be struck, and the potential consequences.
Common warning signs include:
- Dead or dying tops
- Large cavities or decay pockets
- Root plate movement or soil heaving
- Severe or recently changing lean
- Cracked or hanging branches
- Recent trunk, root, or major limb failure
A tree considered high risk may still be standing in a relatively stable condition while the owner arranges documentation, permitting, mitigation, or removal.
An
imminent hazard is more urgent. This may involve active failure, sudden movement, a newly split trunk, a partially fallen tree, or another condition requiring immediate action to protect people or property.
A TRAQ-qualified arborist can document the tree’s condition and recommend monitoring, pruning, cabling, restricted access, or removal. When formal documentation is required, the findings may also be presented in an
arborist report.
Local Tree Codes May Define Hazard Trees Differently
An arborist evaluates tree risk using professional assessment methods, but the city or reviewing agency decides whether the tree meets its legal or regulatory standard for removal.
Requirements vary by jurisdiction. A tree that has defects or receives an elevated risk rating does not automatically qualify for removal under every municipal code. Some cities require a specific risk level, supporting photographs, an arborist report, permit documentation, public notice, mitigation, or replacement planting.
Seattle regulates tree removal based on the tree’s classification, property conditions, permit status, and whether the situation qualifies as hazardous or requires emergency action.
Environmentally Critical Areas,
street trees,
protected trees, and development sites can receive additional oversight. For projects outside Seattle, requirements may differ by city, so the applicable local tree code should be reviewed before removal or mitigation work begins.
