Trinity County, CA Noise Ordinances: Industrial Noise (2026)

Industrial and commercial operations in unincorporated Trinity County are subject to the noise performance standards in Chapter 17.30 of the zoning title. Section 17.30.100(C) states that 'at the lot line the maximum sound pressure level radiated in each standard octave band by any use or facility (other than transportation facilities or temporary construction work) shall not exceed the values' in Table I after applying the Table II correction. Measurement is by a sound-level meter and octave-band analyzer using the flat or 'C' network. Table I sets descending limits across the spectrum - for instance 79 dB for the 20-75 cycles-per-second band, 74 dB for 75-150 cps, stepping down to 39 dB for the 4,800-9,600 cps band. Table II adjusts these: a +5 dB correction for daytime-only operation, with separate corrections for intermittent or impulsive noise, and tighter treatment when noise is not smooth and continuous and is not radiated between 10:00 p.m. and 7:00 a.m. - so nighttime industrial noise is treated more strictly. The same chapter regulates vibration, smoke, odors, and glare. Concrete batch plants and rock screening also carry use-permit conditions, a 7 a.m.-7 p.m. Monday-Saturday window, and a noise-barrier standard reducing levels to 55 dB Leq at the nearest sensitive land use. Cannabis operations face the additional 55 dBA day / 50 dBA night property-line limits and the no-generator 10 p.m.-7 a.m. rule under Section 17.43.060. These standards apply countywide and are enforced through use permits and code enforcement.