Washington County, OR Tree Protection: Heritage & Protected Trees (2026)

Oregon operates a statewide Heritage Tree Program administered by Oregon Travel Information Council and the Oregon State Parks Heritage program, recognizing exceptional trees for size, age, species rarity, or historical significance. Washington County has several state-designated heritage trees including historic Douglas firs in Forest Grove and signature oaks in the Tualatin Valley. Beaverton BC 9.04 and the Beaverton Heritage Tree Program allow property owners to nominate trees (typically 30+ inch DBH or species of special significance) for local landmark status with enhanced protection beyond the standard tree code. Hillsboro CDC 12.32 and the city's Heritage Tree designation process (through Parks and Recreation Advisory Board) protect Oregon white oaks, Pacific madrones, and other natives of exceptional size. Forest Grove, home to Pacific University and some of the oldest settled land in Washington County, has historic trees including the Heritage Oak near downtown. Removal of designated heritage trees requires council-level review and is granted only in cases of imminent safety hazard, typically with certified arborist documentation. Construction near heritage trees requires Tree Protection Zones (TPZ) matching the dripline plus fencing. Damage during construction triggers significant mitigation including replacement planting and fines. ORS 358 Chapter historic preservation framework can overlap.