Washington County, OR Tree Protection: Parkway Planting (2026)

Section 407-7, Urban Street Tree Standards, sets the planting rule that applies whenever a development plan requires street trees along its road frontage. 1 requires species to be chosen from the approved list of street trees unless the Director approves another species through a Type I procedure, and requires trees to be selected and spaced to provide canopy overlap for shade. The default spacing is an average of one tree per 35 feet of lineal road frontage, though the Director can approve wider average spacing through a Type I procedure if the applicant submits evidence the chosen species typically needs more room and the wider spacing will still deliver canopy overlap, or district standards can set a different average outright.

2 lets the Director exempt a project from planting new street trees, again through a Type I procedure, where existing trees on site already meet the code's location and diameter requirements, avoiding duplicate plantings where mature trees already do the job. 3 fixes where trees go: they must be installed on public or private property no more than five feet from the designated right-of-way, keeping the canopy close enough to shade the street itself. 5-inch caliper and 8 feet of height at planting. These street tree standards sit within the broader landscaping chapter, so the installation security, maintenance and 110-percent-of-cost bonding provisions of Section 407-8 apply to street trees the same as any other required landscaping.