Environmental Rules in Thurston County, WA (2026)
6 rules for unincorporated Thurston County, Washington.
Verified from official government sources
Stormwater Management
Thurston County regulates stormwater and erosion through the county's Drainage Design and Erosion Control Manual, adopted by reference in full under Code Section 15.05.010, currently the 2022 Edition. Anyone developing property must design drainage and erosion control to the manual's standards, post a financial guarantee, and maintain the system afterward. Violating the chapter or the manual is a civil infraction under Section 15.05.020, enforced by the county's storm and surface water program manager.
Thurston County Stormwater and Erosion Control Rule
Some RestrictionsThurston County Code §§ 15.05.010, 15.05.020
This section consists of the Drainage Design and Erosion Control Manual on file in the water resources program manager's office as amended. The 2022 Edition of the Drainage Design and Erosion Control Manual for Thurston County ("manual") is adopted by reference as though set forth herein in full. ... Violations of the provisions of this chapter, including the manual standards, are designated as...
Erosion Control
Thurston County requires construction and site development to follow its 2022 Drainage Design and Erosion Control Manual under TCC Chapter 15.05, enforced with civil infractions.
Thurston County Erosion Control Manual
Some RestrictionsThurston County Code § 15.05.010
This section consists of the Drainage Design and Erosion Control Manual on file in the water resources program manager's office as amended. The 2022 Edition of the Drainage Design and Erosion Control Manual for Thurston County ("manual") is adopted by reference as though set forth herein in full. (Ord. 12305 § 1, 2000: Ord. 10610 § 1, 1994: Ord. 9859 § 1, 1991) (Ord. No. 14265, § 1, 8-...
Flood Zones
Thurston County requires any development in a designated floodplain or flood hazard area to go through the county's Critical Areas Ordinance review process, not just standard zoning approval, per TCC 21.54.020.
Thurston County Floodplain Development Review
Significant RestrictionsThurston County Code § 21.54.020
All floodplains or flood hazard areas as designated or described by the Thurston County Critical Areas Ordinance (Title 24 TCC) or the Thurston County Agricultural Activities Critical Areas Ordinance (Chapter 17.15 TCC) for agricultural activities shall be subject to the review processes, standards and conditions as specified in the applicable critical areas ordinance.
Boat Dock Permits
Thurston County bans new boat launching ramps, piers, docks and floats in estuarine wetlands and Category I wetlands outright. On lakes with Category II, III or IV wetlands, they can be permitted only under strict siting, material and maintenance conditions set by TCC 24.30.110.
Thurston County Boat Dock Permit Rules
Significant RestrictionsThurston County Code § 24.30.110
Boat launching ramps, piers, docks and floats are prohibited in estuarine wetlands and Category I wetlands. They may be permitted in lakes with Category II, III and IV wetlands consistent with the Shoreline Master Program for the Thurston Region, as amended, consistent with TCC 24.25.110, and all of the following: A. New Docks, Floats and Piers. Floating docks, floats and piers in lakes may be ...
Vehicle Idling Restrictions
Thurston County caps warm-up idling at 10 minutes for most vehicles and 20 minutes for commercial diesel vehicles under its noise code.
Thurston County vehicle idling limit
Some RestrictionsThurston County Code § 10.36.040(M)
The operation of motorized vehicles for the purpose of ingress and egress to the property, including idling a vehicle to warm the engine prior to departure from property. This is limited to what is customary for a reasonably prudent resident of Thurston County. However, for purposes of warming-up a vehicle, idling is limited to ten minutes for all vehicles except commercial diesel vehicles whic...
Flood Elevation Requirements
Thurston County requires two feet of freeboard above the base flood elevation for new construction and substantial improvements in special flood hazard areas. TCC § 14.38.050(B)(1)(a) sets the elevation floor for residential structures, while § 14.38.020 extends the same two-foot freeboard standard to non-residential buildings, floodproofed commercial buildings, and utility equipment.
Thurston County Flood Freeboard Requirement
Some RestrictionsThurston County Code § 14.38.050(B)(1)(a)
"Freeboard" is an increment of elevation added to the base flood elevation. Thurston County defines "freeboard" as two feet of elevation added to the base flood elevation. Freeboard is required for all residential, non-residential, commercial floodproofed buildings, and utilities (all equipment, electrical, or mechanical items) constructed, substantially improved and/or reconstructed due to sub...
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