Portage County, Wisconsin: drinking water report. Portage County in central Wisconsin has about 71,000 residents, with Stevens Point and the University of…
Portage County in central Wisconsin has about 71,000 residents, with Stevens Point and the University of Wisconsin-Stevens Point as the anchors. The county sits on the Central Sands – a vast sandy plain overlying a highly productive but vulnerable sand and gravel aquifer. Potato, vegetable, and cranberry farming use extensive irrigation from this aquifer, creating a direct connection between agricultural practice and drinking water quality.
Portage County's sandy aquifer is among the most studied and most contaminated agricultural aquifers in Wisconsin. According to the Wisconsin DNR's 2024 Central Sands groundwater report, nitrate concentrations in the surficial aquifer averaged 12.5 mg/L across the county's agricultural zones – above the MCL. A 2024 UW-Stevens Point study found that 30% of private wells in the county exceeded the nitrate MCL, with concentrations above 20 mg/L in the most intensive farming areas.
The aquifer's sandy, permeable nature means contaminants travel fast and far. Atrazine, applied to potato and corn fields, has been detected in 25% of wells tested by the UW-Stevens Point groundwater center. Municipal wells in Stevens Point draw from deeper zones that are somewhat protected but not immune to contamination migration.
Portage County's Central Sands aquifer is essentially an unfiltered window into what happens on the surface. If you are on a private well in the agricultural area, you are drinking water that reflects nearby farming practices with very little natural attenuation.
Check your water for available data. For nitrate and atrazine, reverse osmosis removes both effectively. Our water filter guide covers systems certified for agricultural contaminants. Pull your detailed report for local data, and visit our Wisconsin page for statewide context.