This map shows modeled outdoor noise across Eureka 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 9,657 Eureka residents, or 26.6%, live above that level. By land area, 37.2% of Eureka is above 55 dBA.
See how noise in Eureka compares to similar-sized cities.
Noise by Part of Eureka
Average noise levels for Eureka residents, grouped by direction from the center of Eureka. Northern Eureka carries the highest population-weighted average; Southern Eureka carries the lowest. Just 12% of residents in Southern Eureka live in blocks above the EPA's 55 dBA threshold, a third of the share in Northern Eureka.
Central Eureka
2% of people above 55 dBA
Eastern Eureka
21% of people above 55 dBA
Northern Eureka
38% of people above 55 dBA
Southern Eureka
12% of people above 55 dBA
Western Eureka
39% of people above 55 dBA
Northern Eureka sounds about 53% louder than Southern Eureka to the human ear, a 6.1 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 US Hwy 101 do you need to be?
US Hwy 101 produces an estimated 67 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 24% of Eureka sits under tree canopy (about average for cities) and roughly 45% 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.