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Is My Tree a Hazard?

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We are asked this question every day. While some trees need to be removed to protect people and structures, the good news is that most trees are not dangerous. With careful assessment and proper risk mitigation, the vast majority of trees can be retained in a landscape. 

Tree Risk Assessment
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Tree133 performs tree risk assessments using best practices from the International Society of Arboriculture (ISA).  We regularly evaluate large trees growing in close proximity to people, structures and roadways. Our extensive training and field experience enables Tree133 to evaluate the risk presented by a tree and recommend appropriate options to reduce that risk.

BASIC Assessment

Some trees require further investigation of identified defects and health conditions. If necessary, Tree133 can perform a Level 2 assessment to evaluate specific risk factors and more precisely determine the degree of risk and consequences of a failure. 

ADVANCED Assessment

When critical information about a tree’s condition is not available from the ground or by visual inspection, we utilize advanced assessment methods. This may include a climbing inspection to evaluate the upper trunk, limb attachments or cavities, excavation of the tree’s root collar to inspect structural roots, laboratory analysis of observed fungi or pathogens, and testing of wood density using micro resistance drilling. 


For advanced assessment projects requiring specialized or laboratory services, Tree133 works with highly qualified Arborist partners and university extensions to provide you with the best possible analysis and advice.


Visual Inspection

Each risk assessment by Tree133 begins with a site visit and Level 1 Visual Inspection, performed from the ground, to identify tree defects or conditions suggesting High or Extreme risk. The assessor will perform a 360-degree inspection to evaluate the site, targets, root zone, trunk and canopy.  The assessor will analyze data collected to determine the likelihood and consequences of failure and identify options to mitigate the risk. 


A Level 1 inspection is focused on identifying immediate hazards and providing knowledgeable advice on appropriate risk mitigation. During the site visit, you will receive professional advice regarding tree preservation or removal, risk mitigation options and recommended tree care. Whenever possible, we prefer you attend the site visit, so we may explain our findings and answer your questions.




We had a fabulous experience working with Tree 133. Craig did a very thorough walk of our entire property, assessing the health of each of our trees, addressing our concerns and educating s along the way.

— Alexandra K.

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