Emerald ash borer in Washington

The first Washington detection

The timeline comes from ODF’s September 2026 bulletin, DNR’s Tree Link post of September 8, 2026 and the Washington Invasive Species Council page (updated September 17, 2026). On August 3, 2026, residents in unincorporated Hazel Dell, about four miles north of Vancouver, photographed an unusual beetle on their car windshield and reported it. The specimen reached WSDA on August 5, went to USDA on August 6, and on August 19 USDA APHIS confirmed it as Agrilus planipennis.

Washington’s 2024 Forest Health Highlights still listed EAB as “not yet detected,” with the nearest finds in Forest Grove, Oregon (2022) and British Columbia. DNR’s urban readiness recommendations warn that EAB populations are “often present in forests for 3-5 years before detection,” so one confirmed beetle in Clark County almost certainly means infested trees nearby that nobody has found yet.

For the Oregon side, including the five-county quarantine that starts at the Columbia, see emerald ash borer in Oregon.

What is regulated in Washington right now

As of October 2, 2026 there is no EAB-specific quarantine in Title 16 WAC: the agricultural pest quarantine chapter (16-470) covers spongy moth, hornets, apple maggot, Japanese beetle and others, and no EAB chapter has been added. Two rules still matter to an ash owner:

WSDA’s rulemaking page lists a firewood quarantine dated August 12, 2024; its text could not be read for this page, so the dates above are from the codified chapter. Watch for a WSDA quarantine proposal for Clark County, and check the WISC page for the current status before you move any ash material.

Do not expect a federal rule to fill the gap. USDA APHIS removed its domestic EAB quarantine regulations in 2020, with the final rule effective January 14, 2021, so any movement restriction on ash inside Washington will have to come from WSDA. APHIS’s EAB work now centers on biological control, rearing and releasing stingless parasitoid wasps, plus detection surveys and outreach. Its page (modified April 23, 2026) counts infestations in 38 states and the District of Columbia since the first North American find in southeast Michigan in 2002, and it names the human route that matters most: moving infested ash firewood, logs or nursery stock.

What WSDA, DNR and the Invasive Species Council ask you to do

DNR’s post for tree managers applies just as well to a homeowner with two ash trees. Its list, with the readiness document’s details:

• Count your ash. Know how many you have, how big they are and which ones you would pay to keep.
• Stop planting ash (Fraxinus) anywhere in Washington, and take it off any planting list.
• Limit maintenance on existing ash to what public safety needs; do not invest in routine pruning of a tree you may remove.
• Treat selectively. DNR’s words: selective insecticide treatment for healthy, high-value ash, not wholesale treatment.
• Plan removal and replacement of lower-priority ash with non-host species, and budget for removal, replacement and wood recycling.
• Don’t move firewood. “Buy firewood where you burn it, and burn it where you buy it.”
• Report suspected beetles or symptomatic trees through the Washington Invasive Species Council (invasivespecies.wa.gov or the WA Invasives app). The readiness document also lists APHIS at 1-866-322-4512.

The detailed playbook is the Washington State Emerald Ash Borer Resources and Management Guide, released May 2026 by WSU, DNR and WSDA (a 71 MB PDF linked from WSU’s EAB page), alongside the WSU Extension document “Managing Emerald Ash Borer in Washington State.”

Signs on your tree

Larvae feed under the bark for years before the crown shows it; ODF’s fact sheet says decline typically starts three to four years after infestation. Check the upper crown first, then the trunk on its sunny side:

• D-shaped exit holes, about one-eighth of an inch across, flat on one side and rounded on the other (WISC, ODF).
• S-shaped galleries under loose bark, packed with sawdust-like frass (WSU).
• Crown thinning and dieback from the top down, with leaves dying gradually (WISC).
• Heavy woodpecker damage, which WISC calls a possible sign on an ash, often with pale “blonded” bark patches.
• Sprouts along the trunk and splitting bark as the tree tries to recover (ODF); APHIS also lists vertical cracks in the bark among the symptoms.
• The beetle itself, metallic green and about half an inch long, with a coppery-red abdomen (APHIS). Larvae pupate over winter and adults emerge in spring, live about three weeks, and are most active on warm, sunny days. WSU publishes a Washington EAB lookalike guide; check it before reporting, because many native green beetles get reported every summer.

If the tree is big and near a house, have a certified arborist confirm the diagnosis and rate the hazard; a dead ash loses limbs quickly. What that inspection covers is on tree risk assessment.

Treat or remove?

Washington agencies have not yet published their own treatment thresholds, so the numbers below come from the Oregon guidance DNR links to and from OSU Extension, which has four years of West Coast experience.

Modeled estimate, not quotes (method): removing a 25–50 ft ash in Washington models at $850–$1,700 and a 50–80 ft tree at $1,700–$3,400, with chipping and haul-away but no stump; add 25 percent within 10 ft of a structure. Full figures are on tree removal cost.

Clark County and Vancouver specifics

Vancouver’s tree permit page says a developed single-family lot needs either a Level I permit (site disturbance or building) or a Level III permit for a nuisance or hazard tree, and the city’s tree code was re-codified on July 31, 2026 (Ordinance M-4533; applications now cite VMC 20.450.035), so confirm the current form before you apply.

Street trees with the trunk in the right-of-way need a separate permit under VMC 12.04, and heritage trees (generally 36 inches DBH and up) carry their own protections. County-wide rules and the other 39 cities are in tree removal permits in Washington.

Power lines: Clark Public Utilities clears trees within 10 feet of its overhead lines and offers a free secondary-line disconnect so a crew can work near your service drop; request it through the utility’s online form. Details on Clark Public Utilities tree trimming.

Burning is not an option inside the Vancouver, Camas and Battle Ground urban growth areas: the Southwest Clean Air Agency permanently bans residential yard-debris burning in UGAs and designated no-burn areas (SWCAA 425). Chip it, or haul it to a transfer station; see Washington yard debris burning rules.

What to do this fall

1. Confirm the species. Ash has opposite branches and compound leaves; WSU’s EAB page links an identification guide. The native species, Oregon ash, grows along streams and wetlands west of the Cascades and is highly susceptible to EAB (ODF).
2. Walk the crown with binoculars for thinning, sprouts and woodpecker work. Report anything suspicious through invasivespecies.wa.gov with photos and the location.
3. Decide per tree. High-value and healthy: schedule a licensed applicator for spring injection. Declining or low value: schedule removal and pick a non-host replacement.
4. Keep the wood local. Chip to 1 inch or burn it on site where legal; do not carry ash firewood across county lines or into Oregon.
5. Check the crew at L&I’s Verify a Contractor tool; tree removal is a registered specialty under RCW 18.27.

Removal options, permits and crane work are covered under tree removal; a dead or brittle ash falls under dead tree removal. Other pests and diseases are listed on pests and diseases.