Rural water wells in High Plains Aquifer, which encompasses central Kansas’ Great Bend Prairie Aquifer, show large increase in nitrate levels. That is reason for alarm, said Keith Miller, chairman of the Great Bend Prairie Regional Advisory Committee.

“The future of our water supply is at stake,” said Miller, who farms near Ellinwood. “We need to do everything we can to protect this crucial resource.”

He was referring to a recent study released by Kansas State University that revealed nitrate levels in shallow wells above U.S. Environment Protection Act standards. It went on to say Kansas private well owners should test water quality annually.

“This is an issue we’ve been looking at,” Miller said. “It is something we need to stay on top of.”

The 6,769-square-mile Great Bend Prairie Aquifer was the focus of a 40-year comparison study of rural water wells published in the Hydrogeology Journal. The High Plains aquifer, also known as the Ogallala aquifer, underlies about 112 million acres, or 175,000 square miles, in parts of eight states, including: Colorado, Kansas, Nebraska, New Mexico, Oklahoma, South Dakota, Texas and Wyoming. It is one of the largest underground freshwater sources in the world.

Covering all or parts of 11 central and western Kansas counties, including Barton, the Great Bend Prairie contains just over 5,000 active water wells. As for the use, 95% of the water goes to irrigation, with the balance split pretty evenly between industry, stock water, municipal and recreation.

“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, K-State associate professor of geology and the study’s principal investigator. 

The study

Kirk and Alexandria “Allie” Richard Lane, a K-State 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 based in Stafford. 

“The Great Bend Prairie Aquifer is very vulnerable to contamination and if rural well owners don’t know there is a problem, they obviously can’t do anything about it,” Kirk said. “Municipalities are required to test and provide safe drinking water for city residents but private rural well owners should take responsibility to test their wells at least every year.” 

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.

“Those kits are good to use for basic readings and if anything is concerning, then residents can send a sample to a lab for further testing,” Lane said. “At KDHE, we try to inform private water well communities that it’s important to test their wells annually.” 

In Barton County, one can contact the Environmental Management Office who can handle testing as well.

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. 

“There hasn’t been as much work on water quality as water quantity in the High Plains Aquifer,” Kirk said. “Groundwater storage in the Great Bend Prairie Aquifer is relatively stable, but if the water is there and the quality degrades, that’s also bad.”

Why is this an issue?

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. 

“Other parts of the High Plains Aquifer are most likely going to see changes too but it’s just taking it longer to show up because of transport time between the surface and the water table,” Kirk said.

That transport time is fairly quick in the study area since the soil is sandy and the water table is closer to the surface, Kirk said. In addition, the aquifer and sandy soil are not ideal living environments for the microbes that help clean the water by consuming nitrate.

“Groundwater in the Great Bend Prairie Aquifer often has oxygen and where that is the case, microorganisms typically respire the oxygen instead of nitrate,” Kirk said.

Miller reiterated this. “Other things are a concern as well,” he said.

The leaching of salt into the water is a problem, especially in standing water like Cheyenne Bottoms and Quivira Wildlife Refuge. And, nuclear chemicals have been found in water in western Kansas.

According to the study results, the wells with the highest contamination were those in fields used for crops, and the isotopic evidence — like a chemical signature — show that the nitrate in the aquifer is from fertilizer. Kirk said that fertilizers help farmers increase crop yields but excess fertilizer can contaminate water supplies.

Other sources can include human waste from sewage treatment facilities and livestock, Miller said.

“I don’t know what the future looks like or how we balance these issues — growing food for the world and maintaining health of natural resources to grow that food — but we need to find ways to slow down nitrate accumulation and better manage nitrate into the future,” Kirk said.

What to do?

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.

“We need more data about the seasonal variation in nitrate levels and multiple years of data to really understand the trend of the increase,” Kirk said. “We also hope to sample additional wells to evaluate change over more of the aquifer. We wanted to document this finding and try to spread the word because, at the end in the day, it’s a big increase of nitrate and could affect people’s health.”

A plus side

“Water depth levels are up from a year ago,” Miller said. The aquifer has risen about five feet.

“There’s been more recharge than we’ve seen in years and years,” he said. This can be seen when one looks at the water levels in area sand pits.

“That is good for everybody,” he said, adding it benefits all water users. Although, he added, those with water in their basements may not think this.