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Douglas County, CO Noise Ordinances: Vehicle Noise (2026)

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

Key Facts

In county noise limits?
No -- vehicles excluded
Exclusion citation
Section 1704A.08.2
Governing law
C.R.S. 42-4-225 (mufflers)
Prohibited
Exhaust cut-out or amplifier
Enforced by
Sheriff / State Patrol

Summary

Douglas County's Section 17A excludes motor vehicles, motorcycles, off-highway vehicles and snowmobiles from its noise limits. Loud vehicles are instead governed by Colorado's state muffler law, C.R.S. 42-4-225, which bans exhaust modifications that amplify engine noise.

City-specific rules exist: Castle Rock has its own vehicle noise rules that differ from Douglas County's county-level regulations. If you live in Castle Rock, check the city-specific page instead.

The following uses and/or activities are excluded from the requirements of Section 1703A: ... 1704A.08.2 Motor vehicles, motorcycles, off-highway vehicles, and snowmobiles.

Full Breakdown

Section 1704A.08.2 lists 'motor vehicles, motorcycles, off-highway vehicles, and snowmobiles' among sounds excluded from the county's decibel limits, so a passing loud car is not a Zoning Resolution violation. Instead, Colorado Revised Statute 42-4-225 requires every registered vehicle to have an adequate, properly maintained muffler and prohibits cut-outs, bypasses, or exhaust modifications that amplify or increase engine noise above the original muffler. Enforcement is by the Colorado State Patrol and Douglas County Sheriff. Speed or endurance events are separately excluded only when authorized by the County Commissioners.

Violations & Fines

Loud/modified exhaust is a traffic offense under C.R.S. 42-4-225, enforced by law officers; the county noise resolution does not apply to vehicles.

Frequently Asked Questions

Can I report a loud motorcycle under the noise ordinance?
Not under Section 17A -- vehicles are excluded. Loud or modified exhaust is enforced as a traffic violation under C.R.S. 42-4-225.
Are straight-pipe exhausts legal in Colorado?
No. State law bars muffler cut-offs, bypasses, or modifications that amplify engine noise above the vehicle's original muffler.

Sources & Official References

Other rules in Douglas County

All Douglas County rules

Compare Douglas County to another location·View the Colorado noise ordinances overview

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