10 county-level rules, plus city-specific rules for 2 cities in Boulder County, Colorado.
Verified from official government sources
In unincorporated Boulder County, sound from a non-vehicular source in a residential area cannot exceed 55 dB(A) from 7 a.m. to 7 p.m., dropping to 50 dB(A) at night (7 p.m.-7 a.m.). Cities like Boulder and Longmont set their own quiet hours.
Boulder County Ordinance No. 92-28, Sec. 1.01.050(C)
Sound from a non-vehicular source located in a residential area, shall not exceed the following limits: 7:00 a.m.-7 p.m. of the same day: 55 dB(A); 7:00 p.m.-7 a.m. of the following day: 50 dB(A).
Construction in residential areas of unincorporated Boulder County may not exceed 80 dB(A) from 7 a.m. to 7 p.m., or 75 dB(A) from 7 p.m. to 7 a.m. The higher daytime cap applies for the permitted construction period.
Boulder County Ordinance No. 92-28, Sec. 1.01.050(D)
Construction projects in residential areas shall not exceed the following noise levels... 7:00 a.m.-7:00 p.m. of the same day: 80 dB(A); 7:00 p.m.-7:00 a.m. of the following day: 75 dB(A).
Boulder County's noise ordinance specifically exempts "the sound made by animals," so barking dogs are not enforced under the dB limits. Persistent barking is instead handled as a nuisance or under animal-control rules and, in cities, local barking-dog codes.
Boulder County Ordinance No. 92-28, Sec. 1.01.060(I)
The provisions of Sections 1.01.030, 1.01.040 and 1.01.050 of this ordinance shall not apply to: ... I. The sound made by animals.
Unincorporated Boulder County exempts leaf blowers, lawnmowers, snowblowers, and other hand or power tools of 5 horsepower or less from noise limits when used between 7 a.m. and 10 p.m. Outside those hours, general noise limits apply.
Boulder County Ordinance No. 92-28, Sec. 1.01.060(L)
The sound made by a lawnmower, snowblower, or other hand or power tool of no more than five horsepower, between the hours of 7 a.m and 10 p.m.
Amplified music in unincorporated Boulder County counts against the residential noise caps of 55 dB(A) day and 50 dB(A) night. Music from a parked vehicle is treated as a non-vehicular source, measured 10 feet from the property line.
Boulder County Ordinance No. 92-28, Sec. 1.01.040(C)
The sound of amplified music from a non-moving vehicle on private property or public property which is not a road or highway shall be considered "sound from a non-vehicular source."
Boulder County's noise ordinance does not regulate aircraft. Section 1.01.060(G) exempts "operation of aircraft or other activities which are subject to federal law with respect to noise control," leaving airplane and helicopter noise to the FAA.
Boulder County Ordinance No. 92-28, Sec. 1.01.060(G)
The provisions of Sections 1.01.030, 1.01.040 and 1.01.050 of this ordinance shall not apply to: ... G. Operation of aircraft or other activities which are subject to federal law with respect to noise control.
Boulder County's noise ordinance exempts "property used for manufacturing, industrial, or commercial business purposes" from its dB limits. Colorado's CRS 25-12-103 still caps industrial noise at 80 dB(A) day / 75 night and light industrial at 70/65.
Boulder County Ordinance No. 92-28, Sec. 1.01.060(D)
The provisions of Sections 1.01.030, 1.01.040 and 1.01.050 of this ordinance shall not apply to: ... D. Property used for manufacturing, industrial, or commercial business purposes.
Colorado's state noise statute sets the decibel ceilings Boulder County follows: 55 dB(A) residential, 60 commercial, 70 light industrial, and 80 industrial during the day, each dropping 5 dB(A) at night, measured 25 feet from the property line.
Outdoor music in unincorporated Boulder County must stay within the 55 dB(A) daytime / 50 dB(A) nighttime residential caps, measured 10 feet from the property line. Government-permitted concerts, festivals, and special-use events are exempt.
Boulder County Ordinance No. 92-28, Sec. 1.01.060(C)
The use of property by the state, or any political subdivision of the state, or any of their lessees, licensees, or permittees, for the purpose of promoting, producing, or holding cultural, entertainment, athletic, or patriotic events, including, but not limited to, concerts, music festivals, and fireworks displays.
Every vehicle in unincorporated Boulder County must have a working muffler with no cutoff or bypass. On roads, cars may not exceed 80-88 dB(A) depending on type and speed limit; on private property the cap is 78 dB(A).
Boulder County Ordinance No. 92-28, Sec. 1.01.080
No person shall operate anywhere in unincorporated Boulder County any vehicle having a muffler that has been equipped or modified with a cutoff, bypass, or any similar device or modification.
2 cities in Boulder County have their own noise ordinances rules. Each link goes to that city's dedicated page with code citations.
See every category we cover for Boulder County — parking, noise, fences, fires, animals, pools, and more.
Boulder County Ordinance Hub →