Rising levels of nitrates still contaminating groundwater

Rising levels of nitrates still contaminating groundwater

Monday, March 15, 2021

Nitrate levels in Nebraska’s groundwater are on the rise, especially in portions of Northeast Nebraska.

The Lower Elkhorn Natural Resources District (LENRD) has analyzed the nitrate data gathered as part of the routine Groundwater Quality Sampling Program and found some troubling trends across its 15-county district.

An evaluation of water quality data collected over the past 40 years reveals that nitrate concentrations are continuing to increase in some areas. Most recently, the data indicates elevated concentrations of nitrates in portions of Cuming, Colfax and Dodge counties, reaching levels that could pose health threats to humans and the environment.

“Nitrate in the water is relevant to all of us,” said Mike Sousek, LENRD general manager. “This is our water, the water we drink and use in our homes every day. The water we recreate with, grow our crops with, and plant and grow our lawns and gardens with. But this same water could be affecting our health if it’s not properly managed.”

While the most serious threat from excessive groundwater nitrate is to human health, environmental issues such as harmful algae blooms in lakes are caused or exacerbated by excessive nitrate loads in Nebraska’s waters. Nitrate is often found in surface water, such as rivers and lakes, but it also travels into groundwater supplies, meaning that no source of drinking water is safe from potential nitrate contamination.

The Safe Drinking Water Act requires that nitrate concentration in drinking water not exceed 10 milligrams per liter. This threshold has been established to prevent methemoglobinemia in infants; however, researchers working with the University of Nebraska Medical Center have published studies indicating that prolonged exposure to drinking water containing nitrate levels at or below the threshold of 10 milligrams per liter is associated with increased risks of thyroid disease, central nervous system birth defects, and colorectal, bladder, ovarian and kidney cancers and therefore the threshold does not account for these other health effects.

To date, no studies have attempted to quantify the health and economic impacts because of nitrate in drinking water in the U.S. However, a recent study has presented a “first-of-its-kind” comprehensive assessment of nitrate exposure from drinking water. The study found that up to $1.5 billion and $6.5 billion in medical and indirect costs may be associated with annual nitrate-attributable cancer cases.

With the growing body of science showing that the current drinking water nitrate standard may not be providing sufficient protection to public health, the discovery of areas with elevated groundwater nitrates within the LENRD becomes even more concerning.

A solution is to keep nitrates from reaching Nebraska’s water in the first place. A host of agricultural practices — like the use of cover crops, no-till or conservation tillage, and rotational livestock grazing — can help farmers improve their soil health and decrease applications of chemical fertilizers, which are the source of much of the nitrate in our water. Practices that achieve that goal can also help farmers increase their bottom line.

The grim reality of the situation is that it is not a “one size fits all” scenario when dealing with different land uses, soil type, or availability of labor and equipment resources from one farm to the next.

The UNL recommendations for applying nitrogen fertilizer is a ratio of 1 to 1: 1 pound of nitrogen per bushel of corn. In some areas, producers can get by with much less, even as low as 60% to 70% of the recommended amounts. This equates to big savings for the producer and less opportunity for nitrogen to leach into the groundwater.

“There are producers in our district who are trying innovative technology to improve nitrogen-use efficiencies that are allowing them to increase yields, all while decreasing inputs and lessening the chances for the leaching of nitrogen,” Sousek said. “We encourage everyone to bring ideas and discussions to the table. We’re here to partner with you.”


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