Washington County, OR Tree Protection: Protected Tree Species (2026)
Key Facts
- Regulated Tree threshold
- Native Tree List Category A, 6+ inches DBH
- Base score
- 1 point per inch of DBH
- Bonus species (8 pts each)
- white oak, ponderosa pine, madrone
- Riparian proximity bonus
- +2 points within 100 ft of habitat
- Max retention requirement
- 80% of Tree Value Points
- Applies within
- Significant Habitat inside the UGB
Summary
In Significant Habitat areas within the urban growth boundary, only trees on the county's Native Tree List Category A that are 6 inches DBH or larger count as "Regulated Trees" subject to retention rules, and three species (white oak, Willamette Valley ponderosa pine, and madrone) earn extra retention-point value.
422-9.3 Exceptions to Regulated Tree Definition. The following trees are not Regulated Trees and are not subject to the tree preservation requirements of Section 422-9.5. ... B. Trees (native or non-native) that are not identified in the adopted Washington County Native Tree List as Category A or that are less than 6 inches DBH, unless such trees will be retained to meet the requirements of this section. ... 422-9.4 Tree Inventory ... Additional points for a tree that is: White Oak (Quercus garryana), Willamette Valley Ponderosa Pine (Pinus ponderosa), or Madrone (Arbutus menziesii): 8 points.
Official source re-checked September 7, 2026: no newer edition of the code had been published (publisher’s edition: Community Development Code: Supplement 2 | Code of Ordinances: Supplement 25).
Full Breakdown
Community Development Code Section 422-9 imposes tree inventory and retention requirements on development inside Significant Habitat within the urban growth boundary, covering Upland Wildlife Habitat and Riparian Wildlife Habitat outside Clean Water Services' jurisdiction. 5, unless the applicant chooses to retain it anyway to help meet the retention target. 4 requires an ISA-certified arborist, licensed landscape architect, or Qualified Natural Resource Professional to prepare a tree inventory scoring each tree at 1 point per inch of trunk diameter, plus bonus points for three named species: white oak (Quercus garryana), Willamette Valley ponderosa pine (Pinus ponderosa), or madrone (Arbutus menziesii) each earn an extra 8 points, and any tree within 100 feet of verified Riparian Wildlife Habitat earns 2 more.
5 then sets minimum retention percentages by location: 30% of Tree Value Points on pre-2006 UGB Upland Habitat sites of 2 acres or less, 50% on larger pre-2006 sites, and 80% on post-2005 UGB Upland Habitat and on verified Riparian Wildlife Habitat outside CWS jurisdiction. 6. C.
Violations & Fines
A development or building permit will be denied or conditioned if the property has an existing, undisclosed Code violation under Section 215-2. Removing a Regulated Tree without an approved permit or Tree Inventory in a Significant Habitat area is prosecuted as a Code violation under Chapter 1.14 of the Washington County Code per Section 215-3.
Frequently Asked Questions
Which trees count as "protected" under Washington County's tree code?
Do certain tree species get extra protection?
How much of my site's tree canopy do I have to keep?
Sources & Official References
Other rules in Washington County
Compare Washington County to another location·View the Oregon tree protection overview
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