Iowa has fewer lakes, rivers and streams on its 2020 draft list of impaired waters compared with the 2018 review cycle, the Iowa Department of Natural Resources reported.
“For the first time, there was an overall decrease in the number of combined categories 4 and 5 impairments,” Ken Krier, senior environmental specialist, said Tuesday in a news conference.
Still, 45 percent of 1,300 water body segments reviewed for the 2020 list are impaired — meaning they don’t meet at least one standard for their intended use such as drinking, recreation or supporting aquatic life.
Iowa’s 2020 draft list of the most serious Category 5 impaired waters has 775 impairments on 586 segments of lakes, streams, rivers and wetlands. This is a small decrease from the 831 impairments on 622 water body segments on the 2018 final list approved by the U.S. Environmental Protection Agency.
The 2020 numbers still could go up or down based on public feedback, which can be submitted through Dec. 31 at firstname.lastname@example.org.
The biggest water quality problem for Iowa’s rivers and streams is bacteria, while lakes and reservoirs suffer most from algal growth, Krier said.
More than one-third of the fish kills included in the report were caused by animal waste.
Eastern Iowa water bodies included on the impaired waters list are parts of the Cedar River and Iowa River, as well as Lake Macbride, near Solon; Kent Park Lake, near Tiffin; and Backbone Lake, near Dundee.
“There are a large number of impairments due to nutrients and manure,” said Pam Mackey-Taylor, chapter director for the Sierra Club’s Iowa chapter. “They have them in categories as sediment, algae, fish kills and bacteria, but a lot of the causes can be lumped together as manure or nutrients.”
The Iowa DNR removed 99 water body segments from the list, with about two-thirds delisted because agency staff completed plans for their future cleanup. Those plans, called Total Maximum Daily Load, bump waters down from Category 5 to Category 4.
Wally Taylor, conservation chair for the Sierra Club’s Iowa chapter, said the Iowa DNR needs to carry out those plans.
“A TMDL is simply a statement or plan as to what needs to be done,” he said. “By itself it does not clean up the water.”
The Sierra Club also was critical of the Iowa DNR for assessing only 1,300 water body segments, compared with 1,422 in the 2018 cycle. Krier said there was a decrease in segments assessed for 2020 because data that had been included in the past now was considered outdated.
Segments of the Cedar River between Vinton and Cedar Rapids were removed from the impaired waters list because water monitoring has shown pH levels have fallen in a safe range for two review cycles, the state reported. Segments can be delisted for one problem, but left on the list for others.
Although the Iowa DNR has been compiling an impaired waters list every other year since 1998, officials caution against using it to find long-term trends. Each year’s report includes data for the previous five years and sometimes there are changes in the amount of monitoring done and methodology for monitoring.
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