Rural water wells in High Plains Aquifer show nitrate increase
Kansas private well owners should test water quality annually, according to a recent Kansas State University study that revealed nitrate levels in shallow wells above U.S. Environment Protection Act standards.
“The changes we measured in the Great Bend Prairie Aquifer appear to be large relative to changes observed in a national study by the U.S. Geological Survey,” said Matthew Kirk, Kansas State University associate professor of geology and the study’s principal investigator.
The Great Bend Prairie Aquifer, a part of High Plains Aquifer, was the focus of a 40-year comparison study of rural water wells recently published in the Hydrogeology Journal. Kirk and Alexandria “Allie” Richard Lane, Kansas State University 2018 master’s degree graduate in geology, published the study along with Donald Whittemore, Kansas Geological Survey; Randy Stotler, University of Kansas Department of Geology; and John Hildebrand and Orrin Feril, both with Big Bend Groundwater Management District No. 5.
According to Lane, who now works for the Kansas Department of Health and Environment, there are many kits that can be purchased online for under $40 that test for bacteria, pesticides, lead, copper, iron, nitrate and water hardness in water wells.
Kirk and Lane’s 2016 study measured water chemistries and compared them with 1970s measurements at the same sites. Twenty of 21 wells had increases of nitrate concentrations, or NO3-, compared to the 1970s samples. Seven wells exceeded the nitrate concentrations allowed by the EPA standard for drinking water. In the 1970s study, only one of the wells was above the current EPA standard.
According to Kirk, high nitrate levels in drinking water can cause human and livestock health issues by interfering with transport of oxygen by blood and possibly causing a higher risk of cancer. Too much nitrate in groundwater can also stimulate a release of uranium and selenium from the sediment into the water. While water quantity may be a top concern for many rural areas currently, Kirk said water quality issues may soon rise to the top of the list of rural water problems.
Kirk advocates for precision agriculture to apply fertilizer and planting cover crops—which use excess nitrate in the soil when planted in between the harvest of one food crop and the planting of the next. Kirk said these two practices help reduce runoff of excess fertilizer and are becoming more common with irrigated agriculture in the region. He also said that more studies are needed to evaluate if the drastic increase between the two time periods of the study is leveling off or if it has just ramped up in recent years.
Support for the study was provided by a graduate student research grant from the Geological Society of America, the Kansas State University Department of Geology and the National Science Foundation.
