Snohomish County, WA Noise Ordinances: Aircraft Noise (2026)

030(2) and (3), the numeric decibel limits that otherwise govern sound crossing a property line. That exemption applies around the clock, day or night, and it sits alongside 18 other blanket exemptions in subsection (1), covering everything from railroad and vessel operations to fire alarms and officially sanctioned parades. A second, narrower exemption in subsection (2)(g) separately excuses sounds created by aircraft engine testing and maintenance from the maximum permissible levels, but only during daytime hours, meaning that category of ground noise, unlike in-flight and airport-flight-operations noise, loses its exemption after dark.

050: if the source of the sound is subject to a Conditional Use Permit or a SEPA environmental determination, the exemption only extends as far as the noise conditions of that permit or determination allow, so a permitted airport expansion or heliport, for instance, could still face project-specific noise conditions despite the blanket aircraft exemption. The exemption reflects the reality that airport noise, including operations at Snohomish County Airport (Paine Field), is governed primarily by FAA regulation and federal noise-compatibility planning rather than local decibel limits. 050(1)(a) removes it from the ordinance's reach entirely.