Pierce County, WA Tree Protection: Protected Tree Species (2026)
Key Facts
- Woodland trigger
- 1+ acre, 25%+ oak canopy
- Urban single-tree trigger
- 20 in. dbh or more
- Urban stand trigger
- avg. 15 in. dbh, any size
- Regulating chapter
- PCC 18E.40, Critical Areas
- Pre-clearing step
- Habitat assessment via PPW/GIS review
Summary
Pierce County treats Oregon white oak trees and woodlands as priority wildlife habitat, not ordinary landscaping. A stand at least one acre with 25%-or-more oak canopy, or a single oak of 20 inches diameter or more within the urban growth area, is a protected Fish and Wildlife Habitat Conservation Area under the county's critical areas code.
a. Oregon white oak trees and woodlands. Oregon white oak woodlands, stands, and individual trees meeting the following criteria shall be considered priority habitat and shall be subject to protection under the provisions of this Chapter: (1) Priority Oregon White Oak Woodlands. Stands of Oregon white oak or oak/conifer associations where the stand is at least one acre in size and the canopy coverage of the oak component of the stand is greater than or equal to 25 percent. (See Figure 18E.40-1 in Chapter 18E.120 PCC.) (2) Significant Oaks and Stands. Within the urban growth area, single oaks or stands of oaks smaller than one acre in size when any of the following criteria are met: (a) Individual trees having a diameter at breast height of 20 inches or more; or (b) Oregon white oak stands in which the oak trees have an average diameter at breast height of 15 inches or more regardless of stand size.
Official source re-checked September 8, 2026: no newer edition of the code had been published (publisher’s edition: current through Ordinance 2026-515, and legislation passed through May 26, 2026).
Full Breakdown
a designates Oregon white oak trees and woodlands as a Habitat of Local Importance because of the species that depend on them, layering protection on top of the county's general tree rules. Two thresholds trigger it. First, a Priority Oregon White Oak Woodland is any stand of oak or oak/conifer association that is at least one acre in size with oak canopy coverage of 25 percent or more; that whole stand is regulated regardless of individual tree size. Second, within the urban growth area, a Significant Oak or Stand can be smaller than an acre and still be protected if an individual tree has a diameter at breast height of 20 inches or more, or if a stand of oaks averages 15 inches dbh or more regardless of how large the stand is.
030) before clearing, grading, or building nearby: research potential habitat using the county GIS database, and if oak habitat is confirmed, submit a habitat assessment letter, study, or report prepared by a qualified wetland or wildlife biologist, or by county staff for single-family or agricultural applicants. 20 PCC rather than a simple building permit.
Violations & Fines
Clearing, grading, or building within a designated Oregon white oak priority habitat area without completing the required habitat assessment and, where applicable, mitigation under PCC 18E.40.030 through .050 is a critical-area violation. Because oak habitat is regulated the same as other Fish and Wildlife Habitat Conservation Areas, unpermitted disturbance exposes the property owner to stop-work action and required restoration or mitigation planting before any further permits are issued.
Frequently Asked Questions
Are Oregon white oaks protected trees in Pierce County?
How big does an oak stand have to be before it's regulated?
Can a single backyard oak tree trigger county review?
What has to happen before removing oak habitat for a project?
Sources & Official References
Other rules in Pierce County
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