(June 30, 2025) Polk County is releasing its Water Resource Assessment today. Water quality is far from just a Des Moines problem. Here’s some background—and how Iowa compares with our neighbors.
Iowa sits at the heart of the Midwest, with some of the richest farmland in the country—and some of the most serious water quality problems. Despite increasing attention, Iowa lags behind many of its neighbors in both environmental outcomes and policy response.
Nutrient Pollution and Nitrate Contamination
Iowa is a leading contributor of nitrogen and phosphorus to the Mississippi River Basin. This is largely due to:
* Intensive corn and soybean production
* High livestock density, particularly hogs
* Extensive subsurface tile drainage that rapidly transports nutrients to waterways
A 2023 Environmental Working Group analysis found that over 60% of nitrate pollution in the Raccoon River watershed came from just 29% of the land, illustrating the disproportionate impact of high-intensity agriculture.
Minnesota has reduced nutrient loading by enforcing buffer strip laws, requiring vegetative buffers along public waterways since 2015. Wisconsin enforces manure spreading regulations, especially near vulnerable groundwater areas. Illinois—also a major nitrogen contributor—has adopted nutrient reduction benchmarks, though enforcement remains limited.
In Iowa, nitrate levels in rivers like the Raccoon and Des Moines frequently exceed the federal drinking water standard of 10 mg/L, requiring costly filtration by utilities like Des Moines Water Works. Nebraska and Illinois have seen similar spikes—but with stronger groundwater protections in some regions.
Drinking Water & Public Health
Iowa has among the highest rates of nitrate contamination in private wells nationwide. A 2022 University of Iowa study found that over 20% of private wells in some counties exceeded the safe nitrate limit. Most private well owners are on their own for testing and treatment.
The most direct consequence of Iowa’s water problems is drinking water safety—especially in rural areas relying on private wells.
Nitrate contamination, the most pervasive threat, results when fertilizer and manure leach into groundwater and streams in heavily farmed areas.
High nitrate exposure is linked to:
* Methemoglobinemia (“blue baby syndrome”) in infants
* Increased risk of colorectal, thyroid, ovarian, and bladder cancers
* Possible connections to adverse birth outcomes and thyroid dysfunction
In Nebraska, similar challenges exist, but the state created Groundwater Management Areas with tiered responses, including fertilizer restrictions and mandatory well testing. Iowa has no comparable statewide regulatory system for private wells.
Policy Response: Voluntary vs. Regulatory
Iowa’s approach relies on the Iowa Nutrient Reduction Strategy (INRS), launched in 2013. The plan is voluntary and depends on incentives for farmers to adopt conservation practices like cover crops, wetlands, and bioreactors. Iowa has no nutrient application limits or buffer strip mandates, making it a regional outlier—and drawing criticism from health and environmental experts.
Minnesota pairs incentives with required compliance, including state-funded monitoring and compliance deadlines. Wisconsin combines cost-sharing with enforcement, especially in sensitive watersheds. Illinois uses a statewide nutrient reduction strategy, with regular reporting and both federal and state funding. Nebraska and Missouri use more voluntary models, though Nebraska’s local Natural Resources Districts (NRDs) play a key role in coordinating responses.
Impaired Waters and Monitoring
As of 2024, Iowa listed over 700 waterbodies as impaired under the Clean Water Act, mainly due to nitrate, E. coli, or biological degradation. This is among the highest counts in the Midwest.
Minnesota uses a 10-year watershed monitoring cycle with adaptive management. Wisconsin has watershed-based permits that include pollutant trading and accountability.
Iowa, by comparison, struggles with underfunding and understaffing its impaired waters program, leaving many waterbodies unaddressed for years.
CAFOs and Manure Management
Iowa had 4,203 large concentrated animal feeding operations (CAFOs) by 2022 and led the nation in hog production. Only 167 held NPDES (federal discharge) permits. This produces massive volumes of manure, often in areas lacking proper storage or nutrient management planning. Wisconsin and Minnesota enforce stricter siting requirements, application setbacks, and groundwater protections near livestock facilities.
What We’re Sending Downstream
Iowa’s farm-driven nutrient runoff contributes significantly to water pollution across the region. Nitrogen and phosphorus from our fields flow into the Mississippi River and ultimately feed the Gulf of Mexico’s hypoxic “dead zone,” where low oxygen levels decimate marine ecosystems.
In 2023, the Gulf dead zone measured nearly 3,000 square miles. From 1999 to 2016, Iowa—just 4.5% of the Mississippi River Basin by land area—was responsible for 29% of its nitrate load.
While neighboring states like Wisconsin and Minnesota have implemented enforceable nutrient plans and buffer requirements, Iowa has no such mandates. Without change, we will remain one of the nation’s largest contributors to downstream ecological damage.
Final Thought
Iowa’s water quality problems are not unique—but our policy response is among the weakest in the region. While neighboring states mix regulation, funding, and enforcement to protect water, Iowa continues to rely on voluntary efforts alone.
Clean water advocates warn that without stronger accountability and investment, Iowa’s water will continue to decline—along with the health, ecosystems, and communities that depend on it.
Sources
U.S. EPA, “Nutrient Pollution in the Mississippi River Basin”
USGS, “Sources and Transport of Nitrogen in the Mississippi River Basin”
Environmental Working Group, “2023 Raccoon River Report”
Minnesota Board of Water and Soil Resources, Buffer Law Summary
Wisconsin DNR, “Nutrient Management and CAFO Regulations”
Illinois Nutrient Loss Reduction Strategy (INLRS) 2023 Update
Des Moines Water Works, Nitrate Removal Operations Data
Illinois State Water Survey; Nebraska DEE, Groundwater Quality Reports
University of Iowa, 2022 Private Well Water Study
CDC & National Cancer Institute, Nitrate Exposure Risk Summaries
Nebraska NRDs, Groundwater Management Programs
Iowa Department of Agriculture, Iowa Nutrient Reduction Strategy
Iowa Environmental Council, “State of Iowa Water Quality Policy 2023”
Iowa DNR, 2024 Draft Impaired Waters List
Iowa DNR CAFO & NPDES Permit Data
NOAA, Hypoxia Watch: Gulf of Mexico
NOAA, 2023 Gulf Dead Zone Measurement Report