This map shows modeled outdoor noise across Colusa County at 100-meter resolution, combining road, aviation, and rail sources. Green areas measure below 45 dBA. Orange and red exceed the EPA's 55 dBA outdoor threshold linked to long-term health effects. Use the layer toggles to view each source on its own or all together.
What the numbers sound like
- 30 dBAWhisper
- 40 dBASoft rainfall
- 45 dBAQuiet suburban street at night
- 50 dBAQuiet office
- 55 dBAEPA outdoor threshold: light traffic 100 ft away
- 60 dBANormal conversation an arm's length away
- 65 dBABusy restaurant
- 70 dBAHighway traffic 50 ft away
- 80 dBACity bus interior
Population Above the EPA Outdoor Threshold
The EPA's 55 dBA outdoor reference level is a common benchmark for residential noise exposure, especially for activity interference, annoyance, and long-term community noise concerns. About 4,111 Colusa County residents, or 23.7%, live above that level. By land area, 18.5% of Colusa County is above 55 dBA.
See how noise in Colusa County compares to similar-sized counties.
Noise by Part of Colusa County
Average noise levels for Colusa County residents, grouped by direction from the center of Colusa County. Eastern Colusa County carries the highest population-weighted average; Northern Colusa County carries the lowest. Just 17% of residents in Northern Colusa County live in blocks above the EPA's 55 dBA threshold, about two-thirds of the share in Eastern Colusa County.
Eastern Colusa County
28% of people above 55 dBA
Northern Colusa County
17% of people above 55 dBA
Southern Colusa County
24% of people above 55 dBA
Western Colusa County
24% of people above 55 dBA
Eastern Colusa County sounds about 39% louder than Northern Colusa County to the human ear, a 4.8 dBA gap. Every 10 dBA roughly doubles perceived loudness. Within any of these directions, two homes a quarter mile apart can still differ by 10 or more dBA depending on how close they sit to a major highway.
How far back from I-5 do you need to be?
I-5 produces an estimated 75 dBA at its loudest centerline points. Noise drops logarithmically with distance, with the exact rate depending on what's between you and the road. Tree cover, walls, terrain, and pavement type all matter. At roughly a quarter mile back, traffic fades into the noise level of a soft rainfall.
Calculated from the model's calibrated attenuation formula. About 2% of Colusa County sits under tree canopy (much lighter than most counties) and roughly 31% is impervious surface like pavement and rooftops. Both are folded into the per-place decay rate above. Heavier canopy pulls noise down faster with distance; impervious surfaces slow the drop.