Cass County, North Dakota: drinking water report. Cass County in southeastern North Dakota has about 184,000 residents, with Fargo as the county seat.
Cass County in southeastern North Dakota has about 184,000 residents, with Fargo as the county seat. The City of Fargo draws from the Sheyenne River and the Red River of the North, supplementing with water from the Fargo Aquifer. The flat Red River Valley is one of the most productive agricultural regions in the country – sugar beets, wheat, and corn stretch to the horizon – and the region's spring flooding events regularly challenge water infrastructure.
The Red River carries agricultural runoff from across its vast watershed spanning North Dakota and Minnesota. According to the USGS's 2024 Red River water quality data, nitrate concentrations at the Fargo gauge peaked at 4.8 mg/L during spring snowmelt – below the MCL but significantly above background levels. Sulfate from natural geological sources in western North Dakota tributaries adds to the mineral content, with TDS averaging 650 mg/L.
Hector International Airport in Fargo has documented AFFF firefighting foam use. North Dakota DEQ's 2024 PFAS investigation found PFOS at 10 ppt in monitoring wells near the airport – at the threshold of the federal MCL. The EPA's UCMR5 data also showed low-level PFAS detections in the Fargo municipal supply.
Fargo's water system is well-maintained and treats effectively for the agricultural contaminants typical of the Red River. The primary household concern is the naturally elevated mineral content that affects taste and appliance longevity.
Check your water for current results. For taste improvement and mineral reduction, a quality carbon filter addresses most concerns. For PFAS and comprehensive protection, reverse osmosis handles both minerals and contaminants. Our water filter guide covers both approaches. Get your detailed report for data, and visit our North Dakota page for statewide patterns.