San Marcos, CA Noise Ordinances: Industrial Noise (2026)

Industrial noise in the unincorporated county is regulated through the Section 36.404 sound level table. Industrial zones M50, M52, and M54 are limited to a 70 dBA one-hour average at any time, while S82, M56, and M58 zones are limited to 75 dBA at any time, measured at the property line or any receiving property. Section 36.404(e) fixes the limit for extractive industries (including borrow pits and mines) at 75 dBA at the property line regardless of the zone in which the operation sits. Where an industrial property abuts a quieter zone, the boundary limit is the arithmetic mean of the two zones' limits (Sec. 36.404(e)), which protects adjacent residential neighbors. Section 36.410 adds limits on impulsive noise (single short-duration events of one second or less, such as a gunshot, explosion, or blasting): the maximum sound level may not exceed 82 dBA at residential, village, or civic property, or 85 dBA at agricultural, commercial, or industrial property, when it occurs in 25 percent or more of the minutes in the measurement period (Tables 36.410A); higher limits (85/90 dBA) apply to public road projects. Section 36.404(b) provides that compliance with noise-mitigation measures imposed as conditions of an approved Major Use Permit constitutes compliance with the general limits. Fixed-location public utility transmission/distribution facilities are measured at six feet beyond the easement boundary (Sec. 36.404(f)).