Bonneville County, Idaho: drinking water report. Bonneville County in eastern Idaho has a population of about 123,000, centered on Idaho Falls.
Bonneville County in eastern Idaho has a population of about 123,000, centered on Idaho Falls. The city draws water from an exceptionally productive basalt aquifer – the Eastern Snake River Plain Aquifer, one of the largest and most pristine groundwater systems in the western United States. The Idaho National Laboratory (INL), the country's primary nuclear energy research facility, sits about 50 miles west of Idaho Falls and has injected and discharged radioactive and chemical waste into the aquifer for decades.
INL operations between the 1950s and 1990s injected millions of gallons of radioactive and chemical waste directly into the Snake River Plain Aquifer through deep injection wells. According to the USGS's long-term monitoring program, tritium, strontium-90, TCE, and other contaminants from INL have been tracked in the aquifer plume moving toward Idaho Falls. As of 2024, the contamination plume has not reached municipal production wells, but USGS monitoring data shows it continuing to migrate southeastward.
The EPA's UCMR5 data shows PFAS detections at low levels in the Idaho Falls system. Fire training activities at both INL and the Idaho Falls Regional Airport contribute AFFF-related PFAS to the regional aquifer.
The Idaho Falls municipal system monitors extensively and reports clean water at the tap. But the INL plume is a long-term concern that moves slowly through the aquifer and warrants ongoing awareness.
Check your water for the latest monitoring data in your area. For baseline protection, a reverse osmosis system handles the broadest range of potential contaminants. Our water filter guide explains options for groundwater-dependent communities. Pull your detailed report for historical trends, and visit our Idaho page for statewide context.