Butte County, California: drinking water report. Butte County in northern California's Sacramento Valley has about 211,000 residents, with Chico as the…
Butte County in northern California's Sacramento Valley has about 211,000 residents, with Chico as the largest city. California Water Service and smaller municipal systems draw from a combination of surface water (Feather River, Big Chico Creek) and groundwater from the Sacramento Valley aquifer. The county's agricultural economy – almonds, walnuts, rice, and cattle – dominates the valley floor, while the Sierra Nevada foothills to the east contain historic mining sites.
The 2018 Camp Fire, the deadliest wildfire in California history, destroyed the town of Paradise in eastern Butte County and contaminated the water distribution system. According to a 2024 Paradise Irrigation District report, benzene and other volatile organic compounds leached into the water system from melted plastic pipes during the fire. While the system has been largely rebuilt, some areas remain under advisories as pipe replacement continues.
Agricultural nitrate affects the valley floor aquifer. A 2024 State Water Board investigation found that 8 community water systems in Butte County have nitrate levels above 50% of the MCL. The former Chico Army Airfield has documented PFAS at 7 ppt in monitoring wells.
Butte County residents in the Paradise and Magalia areas should verify the status of their local water system's pipe replacement before drinking unfiltered tap water. The contamination from the Camp Fire was unprecedented, and the rebuild is ongoing.
Check your water for current data at your address. For post-fire contaminated areas, a carbon filter at minimum handles volatile organics. For broader protection including PFAS, reverse osmosis is the better option. Our water filter guide covers both scenarios. Pull your detailed report for local data, and visit our California page for statewide context.
Drinking water is one exposure route. These federal datasets also cover Butte County, CA.
The EPA places Butte County, CA in Zone 3 - the EPA's lowest-risk category, with a predicted average indoor radon level below 2 pCi/L. Zone maps predict an area's radon potential from geology and existing indoor readings; they say nothing about a specific house. Testing is the only way to know your own level.
50% of homes in Butte County, CA were built before 1980, and 12% before 1950. Residential lead paint was banned in 1978, so housing age is the strongest available proxy for lead-paint exposure. This describes the county's housing stock, not any one home.
Modelled annual fine-particle pollution (PM2.5) in Butte County, CA averages 7.8 µg/m³, within the EPA's annual standard of 9 µg/m³. These are CDC modelled county estimates rather than readings from a specific monitor.
How radon zones work · Air quality by county · Lead exposure guide
Across 31 public water systems serving Butte County, CA with EPA lead testing on record, 0 (0%) reported a 90th-percentile lead result above the EPA's 15 ppb action level, and the median is 1.3 ppb. 16 water systems serving Butte County, CA carry a health-based EPA Safe Drinking Water Act violation.
| Most-cited violation type | Systems affected |
|---|---|
| Lead and Copper Rule Revisions | 12 |
| Total Coliform Rule | 2 |
| Lead | 1 |
| Revised Total Coliform Rule | 1 |
| Tetrachloroethylene (PCE) | 1 |
Source: EPA Lead and Copper Rule 90th-percentile tap sampling and EPA SDWIS Safe Drinking Water Act enforcement records, aggregated from the public water systems serving this county. Figures are counts of water systems, not a test of any individual home or tap.