The newest assessment of the historic 400-year-old Davis Meeker Garry Oak tree that partially hangs over Old Highway 99 south of Tumwater was released on Feb. 7.
It turns out, the tree is healthier than previously thought, and cutting it down doesn't necessarily have to happen.
According to a news release from city spokesperson Jason Wettstein, the newest in-depth analysis, performed by Todd Prager & Associates, LLC, presents options for the tree to continue standing.
The full assessment can be found on the city's website. The City Council will be reviewing the document during a work session March 11. Comments can be sent to council@ci.tumwater.wa.us.
In May 2023, an 18-inch diameter branch fell from the tree and onto the roadway. A year later, Mayor Debbie Sullivan called for the tree to be cut down so it would no longer be a threat to safety. The city council then decided in July 2024 to hire another tree professional to perform a risk assessment.
The newest risk assessment includes more extensive sonic tomography — a non-invasive technique used by arborists to assess the internal health of trees by measuring the speed of sound waves traveling through the wood — and aerial inspection of the tree, which brought information forward that wasn't included in the first assessment, according to the news release.
"I want to thank the community for engaging, both those who prioritize public safety and those who prioritize preserving the Davis Meeker Garry Oak," Sullivan said in the news release. "It is encouraging to see that there might be options to save the tree and meet our obligations to protect people in the community."
What does the assessment say?
According to the assessment, it's not anticipated that any part of the tree would fail under normal weather conditions within the next three years. No parts of the tree met the probable likelihood of failure category.
At the same time, three scenarios arborists Rick Till and Todd Prager assessed presented moderate risk ratings: the possibility of a branch falling and hitting an occupied vehicle on the highway; a main stem failing and hitting a nearby airplane hangar; and the whole tree failing and striking the hangar. No scenarios received high risk ratings.
Though removing the tree would eliminate all risk, Till and Prager recommended what they called a "reasonably prudent management alternative."
That alternative includes retaining the tree, pruning to reduce the risk of branch failure, installing supplemental support, and continuing to monitor the tree to address ongoing risks. It could also involve root zone enhancement, decorative fencing and landscaping to restrict access.
The assessment says the residual risk will remain at low or low/moderate levels if these management alternatives are adopted.
Till and Prager said in the assessment that all trees pose a risk if a target is present.
"All mitigation options have trade-offs between enjoying the benefits of trees and accepting some risk exposure," they wrote. "It is valuable to consider the range of options in the context of a baseline level of risk that is commonly accepted when living amongst trees."
They said cost estimates for each risk mitigation option that involves tree work is based on their experience with other projects. They said due to the diversity of trees and the diversity of people managing trees, there is ample space for respectful and professional disagreement regarding individual tree risk assessments and management decisions.
Mitigation options
Basic pruning and monitoring would involve removing deadwood that's 2 inches or larger over target areas such as the highway and nearby hangar and parking lot. The cost, excluding traffic control, would be about $2,000 or half a day of work.
Since limiting access to Old Highway 99 isn't feasible, access to the tree will be limited instead. The assessment says limiting access to space within the dripline or within the height of the tree on the airport side may work.
Doing so would involve installing decorative fencing along the edge of the asphalt in the parking area, and removing three parking spaces to the south of the tree to reduce the risk of a car being struck.
Restoring the soil in those parking spots would improve the available rooting habitat and support the tree's long-term health.
The power service line to the hangar would have to be relocated outside the dripline of the tree. The dripline is a ring around the tree canopy on the ground that receives most of the rainwater shed from the tree canopy.
An engineer and contractor would need to be consulted for this work, and it's unclear how much it would cost.
Pruning could reduce the risk of branch, stem or whole tree failure, according to the assessment. However, removing leaves and branches could limit the tree's photosynthetic capacity and pruning would divert energy away from root and trunk growth to wound response.
"For portions of the tree that pose a greater risk, the balance may tip towards greater reduction," the arborists wrote. "For portions where risk is lower, the balance may tip towards removing less material."
Pruning could cost anywhere between $5,000 and $12,000 for one to two days of work. The work would involve at least one expert climber with advanced pruning skills and one aerial lift with a highly skilled pruning arborist.
The city arborist would be tasked to inspect the tree for deadwood and growth annually. Pruning on a five- to 10-year cycle could be needed, which would cost $2,000 to $10,000 each time.
Removing the tree outright and processing the wood would cost the city between $16,000 and $30,000.
