Cowlitz County, WA Noise Ordinances: Vehicle Noise (2026)
Key Facts
- Muffler required
- At all times, CCC § 11.04.290
- Cutout/bypass devices
- Banned outright
- Compression brake ban
- 7 designated county roads only
- Signage duty
- Public Works, within 30 days
- Brake penalty
- Traffic infraction, capped by RCW 46.63.110(1)
- Emergency exception
- Applies to compression brake ban
Summary
Unincorporated Cowlitz County requires every motor vehicle to run a working muffler at all times and bans cutout or bypass devices under CCC § 11.04.290. A separate ordinance, CCC Chapter 11.05, bans unmuffled engine compression brakes on seven named county roads where the Board has posted warning signs, treating the noise as a public nuisance.
Every motor vehicle shall at all times be equipped with a muffler in good working order and in constant operation to prevent excessive or unusual noise, and no person shall use a muffler cut-out, bypass or similar device on a motor vehicle upon a highway. ... the use of unmuffled compression brakes in some areas within the corporate limits of Cowlitz County disturbs the peace and quiet and disturbs the residents of the county in their rest and in the enjoyment of their property ... the Board of County Commissioners finds the use of such brakes in designated areas to be a public nuisance. ... The use of compression brakes in the following designated areas within the corporate limits of Cowlitz County is prohibited unless such braking system is equipped with a functional muffler ... Violations of this chapter are traffic infractions, and shall be processed in accordance with the Infraction Rules for Courts of Limited Jurisdiction, as now or hereafter amended. Fines imposed for violations of this chapter shall not exceed the maximum penalty set forth in RCW 46.63.110(1), as now or hereafter amended.
Full Breakdown
290 requires every motor vehicle operating on a county highway to be equipped with a muffler in good working order and running constantly to prevent excessive or unusual noise, and it separately bans muffler cut-out, bypass, or similar devices outright. That is a standalone equipment rule enforced without needing a designated zone. 05, Unmuffled Compression Brakes Prohibited, targets Jake-brake style engine braking specifically. 010 that unmuffled compression brakes disturb residents' rest and enjoyment of property and declared the practice a public nuisance in designated areas.
040, using a compression brake without a functional muffler is banned on seven mapped segments: Butte Hill Road off SR-503, China Garden Road past Rogers Road, Hooper Road off Abernathy Creek Road, Rose Valley Road near Rose Valley Elementary School, South Silver Lake Road past Headquarters Road, Tower Road near the Tower Road Bridge, and West Side Highway near the Castle Rock city limits, each defined by a milepost range on file with the county. The ban lifts only for a genuine emergency where an unmuffled brake is unavoidably necessary to protect persons or property. ' The current road list was last amended by Ordinance 23-009 on January 31, 2023.
Violations & Fines
A defective, cut-out, or bypassed muffler under § 11.04.290 falls under the Title 11 general penalty at CCC § 11.04.560: a misdemeanor unless another penalty is specified. Using an unmuffled compression brake in a posted zone is instead a traffic infraction under § 11.05.060, processed under the Infraction Rules for Courts of Limited Jurisdiction, with fines capped at the maximum set by RCW 46.63.110(1).
Frequently Asked Questions
Is a loud exhaust illegal in unincorporated Cowlitz County?
Where are Jake brakes banned in Cowlitz County?
What is the fine for an unmuffled compression brake violation?
Does the compression brake ban apply everywhere in the county?
Sources & Official References
Other rules in Cowlitz County
Compare Cowlitz County to another location·View the Washington noise ordinances overview
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