Iowa impaired waters list grows in 2022

Iowa has more impaired waters now than two years ago, with bacteria and fish kills being the top reasons for listing, according to the state’s 2022 draft inventory.

The Iowa Department of Natural Resources on Friday reported the state has 594 water bodies with a total 783 impairments — up slightly from 585 water bodies with 778 impairments listed on the state’s 2020 list of Category 5 impairment approved by the U.S. Environmental Protection Agency.

Another 157 water bodies have impairments, but the federal government has not required the state to set a pollution limit for those waterways.

About 56 percent of Iowa’s assessed rivers and streams and 67 percent of assessed lakes and reservoirs have impairments, meaning they don’t meet at least one standard for their intended use such as drinking, recreation or supporting aquatic life.

About 40 percent of Category 4 and 5 impairments were caused by bacteria, followed by 17 percent for documented fish kills in those waters, and 7.4 percent for organic enrichment, the DNR reported.

Wally Taylor of Marion, an executive team member for the Sierra Club’s Iowa chapter, said the new data indicate large-scale animal production is to blame for much of Iowa’s water pollution.

“The main cause of river and stream pollution was bacteria, which indicates animal waste,” Taylor said. “And likewise with the fish kills, they said the main cause is animal waste. That points the finger right at CAFOs” — confined animal feeding operations.

The DNR reported 81 fish kills in the last two years, with animal waste causing more than a third of those incidents.

The next largest causes were pesticides at 21 percent and ammonia at 12.3 percent, the DNR reported.

Is there any good news?

Since the 2020 inventory, 48 water body segments have come off the list with the bulk of those delisted because new data shows improvements in pollution levels.

The lake at F.W. Kent Park, near Tiffin, was delisted for bacteria, according to the 2022 draft list. The lake still has a Category 4 impairment for algal growth.

The water quality improvements there follow a two-year, nearly $3 million restoration project completed in 2019.

To reduce the phosphorus flowing from nearby farm fields into the late, Johnson County installed five new catch basins and renovated other basins to better filter the water.

The county also dredged the lake and planted thousands of underwater plants to trap and recycle excess phosphorus and nitrate.

The DNR is seeking public comments on the 2022 draft impaired waters list through March 19. After that, the agency will modify the list based on feedback and send the revised version to the EPA.

You can email comments to the DNR at IRcomment@dnr.iowa.gov or mail comments to Iowa DNR, Attention: IR Comments, Water Quality Monitoring and Assessment Section, Wallace State Office Building, 502 E. Ninth St., Des Moines, Iowa, 50319.

Comments: (319) 339-3157; erin.jordan@thegazette.com

Linn and Johnson County area of Iowa DNR's 2022 Impaired Waters Map

Click or tap on image to view interactive map of Iowa's Category 5 and Category 4 impaired waters.