Quiet hours in Boulder County, CO — also called the noise ordinance, nighttime noise rules, or residential quiet time — define the hours during which excessive noise is prohibited.
Boulder County Ordinance 92-28 sets residential noise limits of 55 dB(A) from 7:00 AM to 7:00 PM and 50 dB(A) from 7:00 PM to 7:00 AM in unincorporated areas. Lawnmowers and power tools under 5 hp are permitted 7:00 AM to 10:00 PM under CRS §25-12.
Unincorporated Boulder County is governed by Ordinance No. 92-28, adopted under CRS §25-12 (Colorado state noise statute) and county zoning authority in CRS §30-28. Section 1.01.050 establishes residential zone limits of 55 dB(A) measured at the property line during daytime hours (7:00 AM to 7:00 PM) and 50 dB(A) at night (7:00 PM to 7:00 AM). Construction noise in residential areas is capped at 80 dB(A) daytime and 75 dB(A) nighttime. The lawnmower and small power tool exception in Section 1.01.060 permits use of equipment under five horsepower between 7:00 AM and 10:00 PM. Vehicle muffler cutoffs and bypass devices are prohibited countywide. Violations under Section 1.01.190 are Class 2 Petty Offenses with a base fine of $30 plus court costs, escalating up to $300 for repeat offenses within twelve months. Boulder County does not impose absolute quiet hours like incorporated cities — enforcement is decibel-based with the lawnmower window as the practical daytime activity envelope. Complaints route to the Boulder County Sheriff non-emergency line at 303-441-4444.
Contact your local code enforcement office for specific penalty information.
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See how Boulder County's quiet hours rules stack up against other locations.
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