Iowa: The Land of 751 Polluted Waterways

Updated: Mar 22

2022 Iowa DNR Impaired Water List Shows No Signs of Improvement


by Diane Rosenberg, JFAN Executive Director


Waterloo, Iowa . Photo Credit: Amdizdarevic/Shutterstock.com

Iowa’s waterways are as dirty as ever. In February, the Iowa Department of Natural Resources (DNR) released its draft of the 2022 impaired waters list. The bottom line: not much has changed. The number of impaired waters tallied at 751, one less than in 2020. The Clean Water Act requires the DNR to submit this list, known as the 303(d) list, to the Environmental Protection Agency (EPA) every two years. Water bodies are evaluated for a variety of point source and non-point source (i.e. agricultural) pollutants.


For the 2022 list, 1382 segments, or roughly half, of the state’s waterways were assessed; 1235 waterways were not. Of those tested, 54% were impaired.


The DNR evaluates a range of waterways: lakes, rivers, streams, reservoirs, and wetlands. Pollutants they look for include E.coli, bacteria, turbidity (water clarity), chemicals, high levels of nitrates (formed out of nitrogen) or phosphorus, pH, fish kills or algae. Rivers, which includes streams, are by far the most polluted with 599 segments impaired – 56% of all the rivers and streams tested. Iowa’s lakes are also heavily polluted with 102 (65%) of those tested landing on the list.


Locally, impaired waters were found in Jefferson and all surrounding counties. In Jefferson County, the Fairfield Municipal Reservoir 2 was polluted with sedimentation and siltation. Lake Darling was cited for E.coli contaminants. Lake Wapello in Davis County was listed because of mercury levels in fish, and Lake Rathbun for turbidity, which can increase algae in water bodies. However, with roughly half the state’s waterways not assessed, it’s difficult to know which other local waterways may be impaired. A map of the state’s impaired waterways is found here. (Scroll in to get county boundaries.)


To develop the list, the DNR determines the intended use of each waterway – whether for recreation, aquatic life including fish consumption, drinking, or a combination thereof – and with that information assigns all assessed waterways into one of five categories:


Category 1 – All designated uses are met without impairments

Category 2 – Some of the designated uses are met without impairments but there is not enough information to determine if all uses are met

Category 3 – There is insufficient information to determine whether any uses are met without impairments

Category 4 – The water body is impaired but a plan to remedy the pollutants, called a total maximum daily load (TMDL), is not required

Category 5 – The water body is impaired, and a TMDL plan is required to reduce the pollutants


A TMDL is a plan to improve water quality that determines the maximum amount of pollutant(s) allowed to enter a water body so that it may again meet its designated use. Once a plan for reducing pollution is developed, the TMDL is then submitted to the EPA for approval. In Iowa, local communities are involved in developing and implementing the TMDL. Once a TMDL is developed, the water body is removed from the 303(d) list, but it may still have pollution levels high enough to prevent it from meeting its designated use.


JFAN reviewed the list of all 1382 tested water bodies. We broke the DNR’s findings down by waterways and categories. The following graphs illustrate the data contained in the 2022 assessment.




The 303(d) list submitted to the EPA is only comprised of Category 5 water bodies and is found on the DNR website here.


In the past the DNR’s reporting format made it easy to search on specific counties to learn if any waterways in that county were impaired. However, several years ago the DNR changed its online format so now it’s not possible to search by county. To identify a county, you must click a specific water body in the complete list of all assessed waters found here. The county is printed in small gray letters at the top of the page.




A new Environmental Integrity Project, report, The Clean Water Act at 50, released on March 17 provides additional, eye-opening data in their analysis. In Iowa, 4,554 – 93% - of all rivers assessed were impaired for swimming and water contact recreation. Impaired lakes were ranked the third highest in the nation with 68,735 acres polluted constituting 83% of all lakes assessed. We’ll look more deeply at this report next month.


Clearly, something is terribly wrong in Iowa.


Iowa’s Polluted Waters Widely Impacts Iowans – and Beyond


The DNR reports that 80% of phosphorus and 92% of nitrate pollution comes from non-point sources, i.e. primarily agriculture. High phosphorus levels lead to algae growth that chokes oxygen out of water and kills off aquatic life. A toxic form of algae thought to be the most widespread, microcystin, can also develop that can sicken people and even kill dogs. Both the Raccoon River and Lake Darling were affected by microcystin at various times.


Dead zone as of July 25-31. Photo Credit NOAA.

High amounts of nitrogen and phosphorus runoff from Iowa’s waterways make its way into the Mississippi River and winds up in the Gulf of Mexico, creating a hypoxic area known as the dead zone. In 2021 the dead zone covered approximately 6334 square miles, the size of Lake Ontario and Lake Erie combined. The hypoxia kills off fish and other marine life, impacting the livelihood and health of Gulf coast communities at a cost of $2.4 billion a year.


In 2013, Iowa implemented the voluntary Nutrient Reduction Strategy (NRS) as part of a 12-state effort to reduce the amount of nitrogen and phosphorus pollution entering the Gulf by 45%. Iowa’s NRS has failed to make a dent in the amount of pollutants flowing out of the state. In 2019, the Iowa Environmental Council estimated it would take hundreds to thousands of years to achieve this reduction at the current rate of remediation.


A 2015 Des Moines Register review of DNR data found that more than 60 Iowa cities and towns had their drinking water contaminated with high nitrate levels between 2010-2015. Additionally, 260 cities and towns, approximately 30% of Iowa municipal water systems, were considered at high risk for nitrate and other pollutants.


Large cities like Des Moines can afford to install expensive denitrification water systems, but the cost for these filtration systems are out of reach for most smaller municipalities. Fairfield doesn’t have a denitrification system, but Fairfield Waterworks reports that nitrate levels are nearly nonexistent. In the facility’s January 12, 2022 report, the nitrate level was under 0.5 ppm.


The DNR estimates that factory farms produce approximately 10 billion gallons of manure each year; an industry estimate puts the number at 20 billion. Too much of that manure is making its way into Iowa waterways through manure over-application, runoff, and spills.



Manure runoff after a heavy rainfall in Penn Township, Jefferson County generated foam in this stream.

Monocropped corn and soy production, which feeds confined livestock and supplies the ethanol industry, relies heavily on CAFO manure and commercial fertilizers. Nitrogen and phosphorus also leaches out of these fertilized fields via tile lines, an underground piping system that drains water from oversaturated fields to nearby streams. (Watch the brief YouTube video below demonstrating a tile line being laid into a field.)



Iowa polluted waters are at crisis levels. Compliance with the Nutrient Reduction Strategy should be mandatory and waterway remediation programs need to be better funded and undertaken through a comprehensive watershed approach, not with voluntary, scattershot projects as is currently done.


Most importantly, a factory farm moratorium must be implemented in order to allow time to reevaluate how Iowa approaches livestock production, and new programs must be developed and funded to promote and expand regenerative alternatives to CAFOs.


Contact your legislators and let them know that our current water pollution crisis comes at a terrible price to all Iowans and that you support a factory farm moratorium. Iowa’s waterways won’t improve until we make dramatic and necessary steps to retool or replace our industrial farming practices.