DNR Releases Latest Impaired Waters List

DNR Releases Latest Impaired Waters List

While the Iowa DNR is reporting a 1.9 percent increase in the number of "impaired waterbodies" in its latest draft impaired waters list, it does not mean that water quality is getting worse, according to a DNR staffer in charge of the report.

“The increase in impaired waters does not necessarily mean that the water quality in the state is worsening, it often is a reflection of the additional monitoring we are conducting,” says Roger Bruner, supervisor of the DNR’s Water Monitoring and Assessment section.

The amount of state-funded water monitoring has not increased since the last report, the DNR says, but additional information does come from other sources, such as the U.S. Geological Survey, the U.S. Army Corps of Engineers, cities and Watershed Management Authorities, as well as neighboring states.

The 1.9 percent increase this cycle also includes 750 impaired waterbodies from two categories of the report; previous reports only included one category. This report includes both Category 4 (meaning the waterbody is impaired, but a federally-required watershed plan called a Total Maximum Daily Load is not required) and Category 5 (impaired and a TMDL is required) waters to calculate the total number of impairments. The DNR says reporting both categories is a more accurate depiction of impairments, but is not required by the EPA.

In the last report two years ago the Category 4 and 5 totals were 736 impaired waterbodies, according to the DNR. There are also 56 impairments that are expected to be removed from the 2014 impaired list, once the draft report is approved by the EPA.

The number of impairments in a state does not indicate general water quality conditions, nor does it indicate severe pollution impacts. The degree of impairment ranges from slight to severe, and reflects the degree to which a water segment (a portion of a stream, river or lake that's been monitored; a stream can also be monitored in multiple locations, hence the use of the term "segments") is meeting its specific state water quality standards. The DNR points to Deer Creek in Mitchell County, the Volga River in Fayette County and West Okoboji Lake in Dickinson County as high quality waters with some degree of impairments.

The impaired waters report lists the waters and the number of impairments caused by pollutants (such as chemical compounds) and pollution (caused by human activity) including: bacteria, biological impacts, fish kills, mercury, low dissolved oxygen, pH, habitat and hydrology impacts, ammonia, temperature and nitrate (for drinking water uses).

Despite the "snapshot" impaired waters report, longer-term trends in Iowa surface water quality show steady-to-declining levels of nitrate and phosphorus in most of Iowa’s monitored rivers and streams during the decade ending in 2012, according to a new U.S. Geological Survey summary. In an new interactive mapping system, the USGS reports:

    • Nitrate levels were rated as trending steady to lower in 18 of 22 Iowa sites tested.
    • Phosphorus levels were rated as trending steady to lower in 23 of 25 sites tested.
    • Only five Iowa sites showed up as “somewhat likely up” or “likely up” in the surveys for either nitrates or phosphorus.

Also, a recent summary of annual monitoring results by the Iowa DNR showed that 75 percent of untreated water in Iowa streams meets or exceeds the Environmental Protection Agency’s 10-parts-per-million nitrate safety standard for finished drinking water. After testing more than 14,000 river water samples the last 16 years, the DNR report shows that only about 10 percent of the untreated stream water exceeded the EPA drinking water standard, and that median nitrate concentrations ranged from 2.8 to 7.3 parts per million. The trends stayed low, despite temporary, weather-induced spikes that can often occur during heavy rainfall events.

In addition, a recent Iowa State University survey found that farmers have invested $2.2 billion invested in conservation in the last 10 years, too. The same survey shows moderate-major increases by farmers in adopting precision fertilization programs, building conservation structures and fine-tuning nutrient management practices.

Another report from Iowa Learning Farms found that farmers planted nearly 630,000 acres of cover crops in 2016, up from only 10,000 acres in 2009.

Now farmers are shifting more of their attention to installing edge-of-field practices, such as bioreactors, saturated buffers and wetlands.

Public comments will be taken through May 29. A revised listed list will then be sent to EPA for approval. Send comments to: Dan Kendall, Water Quality Monitoring & Assessment Section, Wallace State Office Building, 502 East 9th Street, Des Moines, IA 50319, email


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