Woodinville council studies integrated pest management plan, weighing costs and safety as herbicide use is phased out

City staff and partner agencies gave Woodinville City Council a technical briefing Sept. 16 on an integrated pest management (IPM) framework as the city implements a prior directive to phase out routine chemical herbicide use.

Asha D’Souza, lead staff for the study session, said the session was intended to set policy direction, explain treatment methods, and surface pilot projects and budget implications. "This is a study session, not a formal action," she said, framing the conversation around treatment options, public engagement and performance standards.

Joshua (public works staff) described IPM as a tiered, science-based approach that combines biological, cultural, mechanical, physical and, when necessary, targeted chemical treatments. He said the city can rely on prevention and cultural measures in many landscapes but that removing tools such as selective herbicides and mechanized treatments raises clear trade-offs in labor intensity, cost and site suitability. "When we limit chemical tools, we often shift work to more labor-intensive methods and to contracted crews," he said.

King County’s Raquel Stamper (noxious weed control program) outlined legal authority under RCW 17.10 and described selective application techniques — foliar spray, cut-stump painting, lance injection and hollow-stem injection — and the importance of applicator training, signage and public notice. Stamper said county teams often test how low they can make herbicide concentrations while maintaining effectiveness and rely on buffers, entry signage and 48‑hour reentry guidelines to reduce public exposure.

Tor Bell of Mountains To Sound Greenway Trust described multidecade restoration work that pairs selective, limited herbicide use with large-scale revegetation: "We mowed, we selectively treated, then we planted tens of thousands of trees and shrubs to restore canopy and crowd out weeds over time," he said.

Staff presented pilot efforts in Woodinville: a goat trial at Woodinville Heights Park, a pollinator/no-chemical zone near City Hall, modified roundabout plantings, increased signage and QR codes for public education. Staff also provided resource figures: the city has 13 full‑time maintenance employees and six seasonal workers, maintains roughly 90 acres of parks and 14 miles of pedestrian/bike paths, and contracts right‑of‑way landscaping (roughly $7,500 per month). Staff estimated herbicide purchase at roughly $2,500 annually and contracted pest control for facilities at about $4,000 per year.

Council members repeatedly asked for explicit budget comparisons. Council member Bescamo urged a clear, itemized set of scenarios: how much would it cost to maintain current aesthetics with manual removal versus a hybrid approach using targeted herbicide treatments. "If residents want zero chemicals, they need to understand what that costs," she said. Council member Arndt urged a phased transition that prioritizes prevention and plant selection to lower long‑term maintenance costs.

Deputy Mayor Randolph and others raised safety questions — for example, when brush encroaches on travel lanes or when yellow-jacket nests present immediate public-safety risks — and staff said safety will remain the top priority and may require chemical or contracted interventions in limited cases.

Council directed staff to return with more specific budget impact estimates, clearer metrics for level-of-service choices (parks vs. medians vs. sidewalks), and a public-engagement plan that explains what different maintenance levels will look like to residents. Staff said they will also quantify contract vs. in‑house resource impacts and report back with pilot‑project outcomes and proposed outreach materials.