Missoula County, Montana: drinking water report. Missoula County spans western Montana's mountainous terrain, with the city of Missoula serving as the…
Missoula County spans western Montana's mountainous terrain, with the city of Missoula serving as the primary population center alongside smaller communities like Lolo, Frenchtown, and Bonner. The county draws water primarily from the Missoula Valley Aquifer and several surface sources including the Clark Fork River, Rattlesnake Creek, and Blackfoot River tributaries. Mountain West Water, the primary utility serving Missoula, operates multiple well fields across the valley floor while rural areas depend on private wells and small community systems.
Montana's geography creates distinct water quality challenges that affect Missoula County. The state's mining legacy, particularly from historic operations in the upper Clark Fork watershed, has left downstream impacts that monitoring programs continue to track. While Missoula's municipal supply comes primarily from protected aquifer sources rather than surface water intake from the Clark Fork, residents in areas relying on shallow private wells face different risks. The county's position in an intermontane valley means groundwater moves through glacial and alluvial deposits that can concentrate naturally occurring arsenic and uranium in some locations.
PFAS contamination patterns in Montana follow predictable pathways, with detections most common near fire training facilities, airports, and industrial areas where firefighting foam has been used. Missoula International Airport represents one potential source area, though the extent of any local contamination depends on historical practices and hydrogeologic conditions specific to each site. The EPA's UCMR5 testing cycle (2023-2025) is providing the first comprehensive look at PFAS presence in Montana public water systems, with results trickling in throughout the monitoring period. Systems serving fewer than 10,000 people, which includes most of Missoula County's smaller communities, may not be required to test under federal rules despite serving populations that could be exposed.
Lead contamination in western Montana typically originates from older building plumbing rather than distribution pipes. Missoula's housing stock includes pre-1986 construction where lead solder was standard, and homes built before 1950 may contain lead service lines. The city's relatively soft water, while pleasant to drink, can be more corrosive to metal pipes than harder water, potentially increasing lead leaching in buildings with legacy materials. The Lead and Copper Rule requires utilities to test at high-risk locations, but these snapshots don't capture conditions in every home.
If you live in Missoula County, knowing your specific water source matters more than county averages. Check your water to see current testing data for your utility or learn about private well testing if you're outside municipal service areas. Point-of-use filtration addresses both known contaminants and emerging concerns your system may not yet monitor regularly. Review our water filter guide to match treatment technology to your situation, request a detailed report showing all available data for your location, and visit the Montana state page for context on statewide water quality patterns and regulatory developments.