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Thurston County, WA Environmental Rules: Erosion Control (2026)

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

Key Facts

Governing manual
2022 DDECM, adopted by reference
Enforcement
Storm & surface water program manager
Violation type
Civil infraction, Ch. 7.80 RCW
Penalty accrual
Daily for ongoing violations
Financial guarantee
25% of drainage facility construction cost

Summary

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.

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.

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, 8-17-2009; Ord. No. 15355, 1(Att. A, § H), 10-18-2016; Ord. No. 16141, § 1, 4-12-2022)

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

Thurston County adopts the Drainage Design and Erosion Control Manual (DDECM) by reference under TCC 15.05.010, and every development project reviewed by the county must comply with it. Violations of the manual's drainage and erosion standards are civil infractions under Chapter 7.80 RCW, cited by the county's storm and surface water program manager, with penalties that can accrue daily for an ongoing violation. The county can also step in directly: if erosion or drainage problems demand immediate action, Thurston County will perform the remedial work itself and bill the property owner, the property owners' association, or the developer for the full cost, plus a lien if unpaid.

Violations & Fines

Civil infraction under Ch. 7.80 RCW with monetary penalty; daily accrual for ongoing violations; county may bill or lien owner for emergency remediation costs.

Frequently Asked Questions

What manual governs erosion control in Thurston County?
The 2022 Edition of the Drainage Design and Erosion Control Manual, adopted by reference under TCC 15.05.010 and kept on file with the water resources program manager.
What happens if a site violates the erosion control standards?
The county issues a civil infraction under Chapter 7.80 RCW, with penalties that can accrue daily until the violation is corrected.
Can the county fix an erosion problem itself?
Yes. Under TCC 15.05.030, the county can perform emergency remedial work and bill the property owner, HOA, or developer for all costs, securable by a lien.

Sources & Official References

Other rules in Thurston County

All Thurston County rules

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