Linn County, Iowa: drinking water report. Linn County in eastern Iowa has about 228,000 residents, with Cedar Rapids as the county seat.
Linn County in eastern Iowa has about 228,000 residents, with Cedar Rapids as the county seat. Cedar Rapids draws water from the Cedar River and alluvial wells adjacent to the river. The 2008 flood devastated the city's water treatment infrastructure, leading to a complete rebuild of the treatment plant – a modern facility, but one that still processes river water carrying the accumulated agricultural runoff of the Cedar River watershed.
The Cedar River carries high nitrate loads during spring. According to the Iowa DNR's 2024 water quality data, nitrate at the Cedar Rapids intake averaged 8.7 mg/L during April-June, with peak values reaching 12.4 mg/L. The new treatment plant includes nitrate removal capability that the old facility lacked, but the raw water burden requires sustained treatment investment.
The former Iowa Army Ammunition Plant in neighboring Burlington area and the Eastern Iowa Airport in Cedar Rapids both have documented AFFF use. Iowa DNR's 2024 PFAS investigation found PFOS at 8 ppt in monitoring wells near the airport – below proposed state standards but consistently detected.
Cedar Rapids rebuilt its water infrastructure after the 2008 flood with modern treatment capacity. The system is designed to handle the nitrate challenge, but the raw water concentrations during spring flush remain among the highest of any major Iowa city's supply.
Check your water for current results. For the agricultural contaminants typical of Iowa river water, a quality carbon filter addresses most concerns at the tap. For additional PFAS protection, reverse osmosis goes further. Our water filter guide covers both options. Get your detailed report for seasonal trends, and visit our Iowa page for statewide data.