Black Hawk County, Iowa: drinking water report. Black Hawk County in northeast Iowa has a population of about 132,000, centered on Waterloo and Cedar Falls.
Black Hawk County in northeast Iowa has a population of about 132,000, centered on Waterloo and Cedar Falls. The Cedar River serves as the primary water source for Waterloo, while Cedar Falls draws from the Cedar River and supplemental wells. Iowa's agricultural landscape dominates the watershed – the Cedar River drains thousands of square miles of corn and soybean country before reaching the county's intake points.
Nitrate is the defining water quality challenge in Black Hawk County. According to the Iowa DNR's 2024 source water assessment, nitrate concentrations in the Cedar River at Waterloo regularly exceed 10 mg/L – the EPA's MCL – during spring runoff, forcing the treatment plant to activate expensive nitrate-removal processes. A 2023 Iowa State University study found that the Cedar River's average nitrate concentration has increased by 30% since 1980, tracking the intensification of corn agriculture in the watershed.
The EPA's UCMR5 data shows PFAS detections at low levels in both the Waterloo and Cedar Falls systems. The Waterloo Regional Airport has used AFFF firefighting foam. A 2024 Iowa DNR assessment found one system in the county with PFAS above Iowa's health advisory level of 70 ppt for combined PFOS and PFOA.
Nitrate in Black Hawk County is not a temporary problem – it is a structural consequence of the county's position in Iowa's agricultural heartland. Spring is the worst season, but levels can stay elevated for weeks or months during wet years.
Check your water for current data on your system. For nitrate, reverse osmosis at the kitchen tap is the most reliable household solution – boiling water does not reduce nitrate and actually concentrates it. Our water filter guide covers nitrate-specific systems. Pull your detailed report for seasonal trends, and visit our Iowa page for statewide context.