Clark County, Ohio: drinking water report. Clark County in west-central Ohio has about 136,000 residents, with Springfield as the county seat.
Clark County in west-central Ohio has about 136,000 residents, with Springfield as the county seat. The city draws from the Mad River and groundwater wells in the Miami Valley aquifer system. The county's manufacturing base – once anchored by International Harvester, Crowell-Weedon, and other firms – has largely departed, but the environmental footprint remains.
Springfield's Mad River supply benefits from the same productive buried valley aquifer that serves the Dayton region. According to Ohio EPA's 2024 source water assessment, the Springfield wellfield produces naturally filtered groundwater with relatively low treatment requirements. However, the aquifer's vulnerability to surface contamination means agricultural and industrial inputs still reach production wells.
The Springfield-Beckley Municipal Airport has documented AFFF use. Ohio EPA's 2024 PFAS investigation found PFOS at 11 ppt in monitoring wells near the facility. The former Wright-Patterson AFB annex in the eastern part of the county also contributed historical contamination. A 2024 Ohio EPA study found TCE at 4 ppb in one monitoring well near the former Navistar plant – approaching the MCL.
Clark County's water quality is generally good for the Miami Valley, but localized contamination near airports and former industrial sites warrants attention for nearby well owners. Springfield's municipal supply is treated and monitored.
Check your water for data at your address. For the mix of industrial and military contaminants in this area, reverse osmosis at the kitchen tap provides reliable protection. Our water filter guide covers systems suited to buried valley aquifer water. Get your detailed report for local data, and visit our Ohio page for statewide patterns.