Woodbury County, Iowa: drinking water report. Woodbury County in western Iowa has about 105,000 residents, with Sioux City at the confluence of the
Woodbury County in western Iowa has about 105,000 residents, with Sioux City at the confluence of the Missouri and Big Sioux Rivers. The city draws water from the Missouri River alluvial aquifer – wells adjacent to the river that produce groundwater influenced by river water infiltration. Meatpacking and food processing have replaced the traditional grain economy as the primary industrial activity, and their wastewater discharges contribute to the local water quality picture.
The Missouri River carries agricultural runoff from across its vast watershed. According to the Iowa DNR's 2024 source water assessment, atrazine and nitrate are regularly detected in the alluvial aquifer feeding Sioux City's production wells, reflecting infiltration from the river. Nitrate peaked at 6.8 mg/L during spring 2024 – below the MCL but consistently elevated.
The former Sioux City Air National Guard Base has confirmed AFFF use, and Iowa DNR's 2024 PFAS sampling found combined PFAS at 12 ppt in monitoring wells near the facility. The Iowa Army Ammunition Plant in nearby Middletown has also documented PFAS contamination in the broader Missouri River watershed.
Sioux City's alluvial well system produces water that reflects Missouri River quality. Spring agricultural runoff season drives the highest contaminant concentrations, making seasonal awareness useful for residents thinking about filtration.
Check your water for data at your address. A carbon filter handles atrazine and taste issues, while reverse osmosis adds nitrate and PFAS protection. Our water filter guide covers systems for alluvial groundwater. Pull your detailed report for seasonal trends, and visit our Iowa page for statewide patterns.