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Thurston County, WA Tree Protection: Parkway Planting (2026)

Some Restrictions
Compiled from the official code textEditor Martyn O'NeillLast verified September 2026

Key Facts

Coverage area
Olympia Urban Growth Area only
Species/spacing
Must be county-approved
Plan requirement
3-year maintenance cost estimate
Preparer
Professional forester or certified arborist
Exemptions
Single-family lots, 4-or-fewer-unit additions

Summary

Within the Olympia Urban Growth Area, Thurston County requires street trees as part of frontage improvements on qualifying development under Code Section 23.36.060(G)(3), with species and spacing approved by the county. Section 23.36.080 forces applicants to fold a full street tree planting plan, covering species, spacing, installation, and a three-year maintenance cost estimate, into the project's soil and vegetation protection plan.

These county ordinances apply to unincorporated areas of Thurston County. Incorporated cities within the county may have their own rules that take precedence over county-level regulations.

2.Tree Distribution. Trees in Soil and Vegetation Protection Areas shall be comprised of at least sixty percent evergreen species, unless site conditions are not suitable as determined by the Urban Forester.3.Street Trees. Street trees shall be required as part of frontage improvements pursuant to the Olympia UGA Zoning Ordinance. The species and spacing of required trees shall be approved by the county, consistent with the provisions of this chapter. ... d.Street Trees. Street trees shall be included as one of the required sections of the soil and vegetation protection plan. ... shall include the following information:i.Location, size, and species of trees to be planted;ii.Description and detail showing site preparation, installation and maintenance measures;iii.Timeline for site preparation, installation and maintenance of street trees;iv.Cost estimate for the purchase, installation and maintenance for a minimum of three years of street trees;v.The description and location of any underground or overhead utilities within the right-of-way or near proposed street trees;

View official code

Official source re-checked September 7, 2026: no newer edition of the code had been published (publisher’s edition: Code of Ordinances: Supplement 77).

Full Breakdown

040. 060(G) sets tree standards for all zones in that area: subsection (G)(2) requires at least sixty percent evergreen species within any Soil and Vegetation Protection Area unless the Urban Forester finds site conditions unsuitable, and subsection (G)(3) requires street trees as part of frontage improvements under the Olympia UGA Zoning Ordinance, with the county approving both the species and the spacing. 080(A)(1)(d) makes street trees a mandatory component of the soil and vegetation protection plan every qualifying applicant must submit before a permit issues.

That plan must show the location, size, and species of every street tree to be planted, describe site preparation, installation, and maintenance measures, set a timeline for planting and upkeep, estimate the cost of purchasing, installing, and maintaining the trees for a minimum of three years, and map any underground or overhead utilities near the proposed planting locations. 080(A)(1). Coverage standards elsewhere in the chapter require eighty percent plant coverage within three years and prohibit lawn in parking lot planting areas except for approved stormwater conveyance, reinforcing that the frontage and street tree plantings required here are meant to establish a lasting canopy along Olympia UGA streets, not a temporary landscaping gesture.

Violations & Fines

A development inside the Olympia Urban Growth Area that omits the required street tree plan, or plants species and spacing the county has not approved under Section 23.36.060(G)(3), cannot obtain plan approval because Section 23.36.080(A) makes the soil and vegetation protection plan, including its street tree component, a mandatory submittal prepared by a qualified professional forester or certified arborist. The county reviews and can reject an incomplete or noncompliant plan before any building or land division permit is issued.

Frequently Asked Questions

Does Thurston County require street trees on every development?
Only within the Olympia Urban Growth Area, and only for development covered by Chapter 23.36, which exempts individual single-family lots and projects adding four or fewer attached dwelling units under Section 23.36.040. Qualifying commercial, multifamily, and larger residential projects must include street trees as part of their frontage improvements under Section 23.36.060(G)(3).
Who decides what species of street tree I can plant in the Olympia UGA?
The county does. Section 23.36.060(G)(3) requires that both the species and the spacing of required street trees be approved by Thurston County, consistent with the rest of Chapter 23.36's landscaping standards, rather than left to the applicant's preference.
What has to be in a Thurston County street tree plan?
Section 23.36.080(A)(1)(d) requires the plan to show the location, size, and species of each tree, describe site preparation, installation, and maintenance steps, set an installation timeline, estimate purchase and at least three years of maintenance cost, and map nearby underground or overhead utilities.

Sources & Official References

Other rules in Thurston County

All Thurston County rules

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