Pam Mackey Taylor is the Director of the Iowa Chapter of the Sierra Club.

The U.S Environmental Protection Agency (EPA) recently notified the Iowa Department of Natural Resources (DNR) that several Iowa rivers which are used for drinking water need to be put on the impaired waters list—also called the 303(d) list—because they are polluted with nitrate and nitrite. Nitrate and nitrite are toxic to humans. 

The affected rivers are the Cedar River, Des Moines River, Iowa River, Raccoon River, and South Skunk River. There were numerous water samples exceeding the federal water quality standard for surface waters used for drinking water. 

This development is significant, because it means DNR will have to take actions to reduce the nitrates and nitrates in these rivers in order to protect drinking water. With these rivers on the impaired waters list, the DNR can no longer ignore the continuing pollution of these waterways with nitrate and nitrite. 

Because 95 percent of Iowa’s land is farmed, the largest contributor to the nitrate and nitrite problem is manure and commercial fertilizer that runs off farm fields. The cycle begins when plants do not absorb all of the fertilizer and manure that was applied to the fields. Rain and snow melt transport the excess nitrate and nitrite off the fields and into rivers, streams, and lakes.

The impaired waters list, which the DNR creates every two years, identifies the rivers, streams, lakes, and wetlands that are polluted. The EPA is responsible for approving the DNR’s impaired waters list.

EPA told DNR that they were using the wrong method to determine whether a water body exceeds the water quality standard for nitrate and nitrate in surface waters used for drinking water. The correct method is to use each test to determine if the nitrate, nitrate, or nitrate plus nitrite was higher than the water quality standard. 

The DNR was using a statistical method to determine the amount of nitrate and nitrite in those rivers used for drinking water. That method allowed the DNR to avoid listing the waters on the impaired waters list.

Even worse, EPA told DNR about the problem during the open comment period on the draft list. DNR ignored EPA’s comments and submitted the 2024 impaired waters list without including the Cedar River, Des Moines River, Iowa River, Raccoon River, and South Skunk River.   

EPA also told the DNR that they failed to include test data from several other sources. One of those is the Iowa Water Quality Information System, which contains data from Iowa’s Institute for Hydrologic Research and U.S. Geological Survey. The DNR also ignored the volunteer data in the Clean Water Hub.

Iowa’s Credible Data Law defines what information can be used in creating the 303(d) list, but EPA said that “data excluded from the state’s analysis must be based on a technical, science-based rationale and not rely solely upon Iowa’s ‘Credible Data Law.’”

Another important item from the decision document: EPA is in discussion with the DNR about the development of Total Maximum Daily Loads (known as TMDLs), and how the DNR is prioritizing its work on TMDLs. This is a significant development. 

A TMDL is a calculation for how much pollution can be put into the water body and still maintain water quality standards. The DNR is responsible for creating TMDLs for all waters on the state’s impaired waters list. Along with the TMDL calculation, DNR creates a Water Quality Improvement Plan, which lays out what is required to bring the water body back into compliance with water quality standards.   

Earlier this year, Sierra Club filed a dedelegation petition asking EPA to remove Iowa’s authority to administer the Clean Water Act. Among the reasons for the dedelegation: DNR was not prioritizing the development of the TMDLs. Some of the water bodies on the impaired waters list have been on the list since 2006 and 2008, with no TMDL having been prepared. 

Some of the waters dating back to 2006 and 2008 are designated as Outstanding Iowa Waters. That status means they are entitled to extra protection—yet DNR has designated them as low priority for preparing TMDLs. That practice is a clear violation of the intent, if not the specific language, of the federal Clean Water Act, which says that the priority ranking must be made “taking into account the severity of the pollution and the uses to be made of such waters.” These waters, given their status and their high social impact as trout streams, are not given their proper priority to the scoring system.

The DNR must do better. The Sierra Club Iowa Chapter will continue being a watchdog over the DNR and its enforcement of the Clean Water Act.

EPA is seeking comments about adding the Cedar River, Des Moines River, Iowa River, Raccoon River, and South Skunk River to Iowa’s 2024 303(d) list. You can send an e-mail by December 13, 2024, to R7-WaterDivision@epa.gov saying that you support adding the Cedar River, Des Moines River, Iowa River, Raccoon River, and South Skunk River to Iowa’s 2024 303(d) list.

For additional information, read the EPA Region 7’s 2024 Decision Document, Iowa’s Clean Water Act Section 303(d) List of Water Quality Limited Segments Still Requiring TMDLs, issued on November 12, 2024.

To read the Dedelegation Petition, see the August 2024 edition of the Iowa Sierran newsletter.