Survey covered only 75% of forested acres following staff reductions at the USDA Forest Service and Washington Department of Fish and Wildlife; future of 80-year-old program unclear.
OLYMPIA — The Washington State Department of Natural Resources released its annual Forest Health Highlights report on Monday following a 2025 survey season defined by a period of unprecedented structural and administrative challenges.
The joint aerial detection survey (ADS) flown by DNR and USDA Forest Service (USFS) staff covered 16.5 million acres of forested land across Washington, accounting for roughly 75% of the 22 million forested acres in the state and the first time since 2021 that a full survey was not completed.
Mid-year personnel changes in USFS Region 6 (also known as the Pacific Northwest Region) included the loss of permanent, dedicated, full-time ADS staff. The Washington Department of Fish and Wildlife (WDFW) terminated its pilot position in August and retired its Partenavia P68 aircraft, which served as a critical resource for ADS work for more than a decade.
“One of my biggest concerns with the restructuring of the Forest Service is how changes to the federal workforce could negatively impact critical programs in Washington state,” Commissioner of Public Lands Dave Upthegrove said. “We value our strong, positive relationship with the Forest Service and are in close contact with them. It is imperative that federal leadership restore the positions necessary to ensure the continued success of our joint aerial survey.”
Department of Natural Resources (DNR) staff pivoted to take over ADS program leadership from the USFS and relied more heavily on aircraft from the DNR Wildland Fire Management Division to execute a modified survey, ensuring vital forest health data remains available for much of the state.
Going forward, the loss of experienced staff, expanded administrative burdens, and the use of more costly private vendors will significantly affect DNR’s ability to survey the entire state without consistent federal funding and reinstatement of USFS ADS positions. The two agencies have historically shared the responsibility of documenting tree mortality and decline throughout the state to deliver a comprehensive view of the landscape impossible to achieve through ground-based observation alone.
“Despite the challenges this season faced, our team was able to gain an aerial view of a majority of our state’s forests including prioritizing the areas we knew had emergent forest health concerns,” said Washington State Forester George Geissler. “This year’s effort amidst dynamic capacity challenges displays our agency’s strong commitment to this annual data collection on our forests conditions to inform our management strategies.”
Summary of Survey Findings
The 2025 ADS recorded some level of tree mortality, defoliation, crown damage, or foliar disease on approximately 391,000 acres – a decrease of more than 150,000 acres from 2024, but certain to be an undercount given limitations of the 2025 survey.
An outbreak of western spruce budworm remained active and clearly visible along state Route 20, affecting about 150,000 acres from the Mt. Baker area in Whatcom County east to Chelan and Okanogan counties. While the size of the outbreak is not uncommon — the last major outbreak in 2011 covered more than 500,000 acres — an outbreak reaching as far west as central Whatcom County is unprecedented.
“The area affected by western spruce budworm has more than doubled in the last two years,” DNR Forest Entomologist Glenn Kohler said. “The unusual activity so far west in the Mt. Baker area is persisting. Spring sampling indicates we’re likely in for another year of damage and potential spread to new areas in 2026.”
A second cyclical outbreak is likely on the horizon in eastern Washington. The average number of Douglas-fir tussock moth captured by pheromone-based traps increased threefold in 2025 compared to 2024. This is often a precursor of outbreaks that historically occur every 7-10 years; the most recent outbreaks in 2018 and 2019 defoliated 7,500 acres in Chelan, Okanogan, and Kittitas counties following a period of unusually high trap counts.
Areas with elevated trap catches in 2025 included locations in Kittitas, Klickitat, Yakima, and Okanogan counties. Larvae and egg masses were also observed in Klickitat County and in Lincoln County, near Grand Coulee. High trap-catch numbers do not always correlate with the exact location of future defoliation events.
Click here to read the complete 2025 Forest Health Highlights report and for a selection of images and graphics featured in the report.
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