10 county-level rules, plus city-specific rules for 4 cities in Snohomish County, Washington.
Verified from official government sources
In unincorporated Snohomish County, nighttime is 10:00 p.m. to 7:00 a.m. weekdays (to 9:00 a.m. weekends). During night, the maximum permissible sound levels received in rural or residential districts drop by 10 dB(A), so a 55 dB(A) daytime limit becomes 45 dB(A).
SCC 10.01.030(3)(b)
At night, as defined in sub-section 10.01.020(18), the maximum permissible sound levels are reduced by ten dB(A) where the receiving property lies within a rural or residential district of Snohomish county, except for sound sources exempted under sub-section 10.01.050(3).
Construction noise in unincorporated Snohomish County is a public disturbance noise when it occurs at night in a rural or residential district, unless a public-disturbance exemption permit is obtained under SCC 10.01.050(6). By day, construction equipment at temporary sites is exempt from the decibel limits.
SCC 10.01.040(2)(c)
Construction activity, including blasting, unless a public disturbance exemption permit pursuant to SCC 10.01.050(6) is obtained.
Keeping animals whose frequent, repetitive or continuous noise unreasonably interferes with the peace and comfort of persons in rural or residential districts is a public disturbance noise at any hour under SCC 10.01.040(1)(a). 'Repetitive barking' means 10 minutes or more within any half-hour span.
SCC 10.01.040(1)(a)
Keeping or harboring any animal or animals whose frequent, repetitive or continuous noisemaking unreasonably interferes with the peace and comfort of persons in rural or residential districts, except farm animals in zones where farm animals are allowed...
Snohomish County has no daytime leaf-blower ban, but operating a leaf blower, saw, drill, sander, grinder, fan, garden tool or similar device at night in a rural or residential district is a public disturbance noise under SCC 10.01.040(2)(a), except emergency work.
SCC 10.01.040(2)(a)
Operation within a rural or residential district of any mechanically powered saw, drill, sander, grinder, blower, fan, garden tool or similar device, except devices engaged in emergency work exempted under section SCC 10.01.050(1)(g).
Amplified or reproduced music heard as comprehensible rhythms inside another residence, or outdoors 75 feet or more from the source in any district, is a day-and-night public disturbance noise under SCC 10.01.040(1)(g) in unincorporated Snohomish County.
SCC 10.01.040(1)(g)
The creation, by use of a musical instrument, sound amplifier or other device capable of producing or reproducing sound, of sounds heard as comprehensible music rhythms or felt: (i) Within a residence not originating the noise, or (ii) Outdoors in a commercial, rural or residential district at a distance of 75 feet or more from the noise source.
Snohomish County does not regulate aircraft noise: SCC 10.01.050(1)(a) exempts sounds from aircraft in flight and airport flight operations at all times. Aircraft noise is governed by the FAA, not county code. New homes near airports may require noise buffering under SCC 10.01.070(3).
SCC 10.01.050(1)(a)
Sounds originating from aircraft in flight and sounds which originate at airports and are directly related to flight operations.
Industrial-source noise received on residential property in unincorporated Snohomish County is capped at 60 dB(A) daytime (SCC 10.01.030(2)), dropping 10 dB(A) at night. Washington's WAC 173-60-040 mirrors this: Class C source into Class A residential receiving is limited to 60 dBA, minus 10 dBA nighttime.
WAC 173-60-040
No person shall cause or permit noise to intrude into the property of another person which noise exceeds the maximum permissible noise levels set forth below in this section. ... Between the hours of 10:00 p.m. and 7:00 a.m. the noise limitations of the foregoing table shall be reduced by 10 dBA for receiving property within Class A EDNAs.
SCC 10.01.030(2) sets dB(A) limits at the receiving property boundary by district. Residential receiving property allows 52 (rural source), 55 (residential source), 57 (commercial), 60 (industrial). Rural receiving property is 49/52/55/57. Night cuts residential/rural limits by 10 dB(A).
SCC 10.01.030(2)
Measurement of sound levels from all sources except motor vehicles on public roads shall be made at or within the property boundary of the receiving property. Maximum permissible sound levels for districts within unincorporated Snohomish county, expressed in dB(A)'s, are: ... RESIDENTIAL 52 55 57 60.
Outdoor music from an instrument, band or amplifier is a public disturbance noise at any hour when heard as comprehensible rhythms 75 feet or more from the source (SCC 10.01.040(1)(g)). A public-disturbance exemption permit under SCC 10.01.050(6) can authorize an event.
SCC 10.01.040(1)(g)(ii)
Outdoors in a commercial, rural or residential district at a distance of 75 feet or more from the noise source. Such sounds include band sessions, automobile sound systems, and electronic sound reproduction equipment whether the source of the sound is stationary, portable, or in a motor vehicle.
Unmuffled exhaust on motor vehicles, off-road vehicles and watercraft is a day-and-night public disturbance noise under SCC 10.01.040(1)(b). SCC 10.01.030(4) also sets on-road dB(A) caps measured 50 feet from the lane: motorcycles 78/82, cars and light trucks 72/78.
SCC 10.01.040(1)(b)
The use of unmuffled exhaust systems on motor vehicles, off-road vehicles and recreational watercraft.
4 cities in Snohomish 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 Snohomish County — parking, noise, fences, fires, animals, pools, and more.
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