Landscaping Rules in Thurston County, WA (2026)
4 rules for unincorporated Thurston County, Washington.
Verified from official government sources
Tree Removal & Heritage Trees
Developers must retain or replant trees to average 100 tree units per acre, with 30% of landmark trees and 70% of heritage trees kept on site.
Thurston County Tree Replacement Rule
Some RestrictionsThurston County Code § 17.27.400
All sites which are subject to provisions in this chapter shall retain or replant trees to maintain an average of one hundred tree units per acre.2.Calculation. If the calculation of the number of trees results in a fraction of 0.5 or greater, the applicant shall round up to the next whole number. If the calculation of the number of trees or shrubs results in a fraction of less than 0.5, the ap...
Weed Ordinances
Thurston County has no general lawn or grass height limit for improved parcels; its weed ordinance instead targets designated noxious weed species. Chapter 17.30 lets the county's Noxious Weed Control Board require containment measures wherever a listed noxious weed is found, and every violation is both a public nuisance and a Class I civil infraction.
Thurston County Noxious Weed Containment Law
Some RestrictionsThurston County Code §§ 17.30.010, 17.30.020, 17.30.090(D)-(E)
17.30.010 - Purpose. The purpose of this chapter is to limit economic loss and adverse effects to Thurston County's agricultural, natural, and human resources due to the presence and spread of noxious weeds, and to establish measures to contain certain noxious weeds designated by the Thurston County Noxious Weed Control Board. ... 17.30.020 - Authority and applicability. This chapter shall be a...
Water Restrictions
On county-run water systems, sprinkler and irrigation use is banned during active firefighting and outdoor watering can be curtailed anytime the department decides it's needed.
Thurston County irrigation water rules
Significant RestrictionsThurston County Code § 15.10.210
No person shall knowingly use water from a water system for lawn or garden sprinkling/irrigation while a fire is being extinguished within the water system service area. The outdoor use of water and use of water for other than domestic purposes shall be under the jurisdiction of the department and shall be subject to change from time to time if the need arises.
Rainwater Harvesting
Thurston County doesn't mandate rainwater harvesting, but it rewards it. TCC § 15.06.020 defines rainwater harvesting as collecting roof runoff for uses like landscape irrigation or toilet flushing, and § 15.06.040(E) cuts a qualifying commercial building's stormwater utility rate by 10%, with an additional 10% if the system captures runoff from over 90% of the roof.
Thurston County Rainwater Harvesting Rate Credit
Light RestrictionsThurston County Code § 15.06.040(E)
"Rainwater harvesting" means the collection, storage and use of rainwater from the roof as a non-potable water source for a building. The uses may include landscape irrigation, toilet flushing or other uses approved by the appropriate permitting authority. ... E.Rainwater Harvesting Rate Reduction.1.For qualifying commercial buildings, the rates and charges set by subsections A and B of this se...
All Thurston County ordinances
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