PIPESTONE COUNTY — The cover crop greening up in Tom Griebel’s field just outside Holland will reduce nitrate levels in the shallow aquifer that supplies drinking water to some of Lincoln Pipestone Rural Water’s 4,700 customers.

The 114-acre field is part of Pipestone Soil & Water Conservation District’s nitrate reduction effort targeting 1,912 acres of ag land here and in other highly vulnerable drinking water supply management areas affecting Edgerton’s municipal treatment systems.

A Clean Water Fund grant from the Minnesota Board of Water and Soil Resources offset the cost for Griebel to buy seed and hire someone with the expertise and specialized equipment necessary to plant cereal rye and winter wheat after last fall’s soybean harvest.

“I was interested in trying it anyway, and the funding just pushed me over the edge,” Griebel said. The reason: “Of course to improve profits, but also to improve soil health and to keep the nutrients such as nitrates out of the water system.”

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For their three-year commitment, farmers who plant cover crops receive $40 per acre per year; those who plant perennial vegetation such as alfalfa or Kernza receive a one-time $200-an-acre payment. The $299,520 grant runs through 2023.

To date, 17 producers within Holland and Edgerton’s drinking water supply management areas have enrolled 22 parcels ranging from 6.7 acres to 263 acres. All told, farmers enrolled 875 acres in perennial vegetation and 746 acres in cover crops. Another 291 acres were slated for cover crop enrollment this spring.

“The ultimate goal would be to have the majority of these drinking water supply management areas in some sort of soil health practices,” said Laura DeBeer, a Pipestone SWCD-based water resources technician. Her position is partly funded by the Minnesota Department of Health for one-on-one work with producers and water suppliers throughout the six-county region.

“Nitrates are quite mobile in the soil profile,” DeBeer said, explaining the value of perennial vegetation and cover crops. Nitrates that aren’t taken up by growing root systems can leach into the groundwater. Shallow aquifers beneath gravely and sandy soils are more susceptible.

Perennial crops use nitrogen as they grow. Cover crops use nitrogen and then, as plants decompose, release it to fertilize the next season’s cash crop.

“Ultimately we just would like to see more growing roots in the area, being it either perennial vegetation or cover crops between cash crops,” DeBeer said, “and really having the producers in the area know and understand their role in drinking water protection.”

The Minnesota Department of Health links nitrates to blue baby syndrome. The U.S. Environmental Protection Agency’s standard for nitrates in drinking water is 10 parts per million (ppm). For treatment to stop, nitrate levels must remain under 7 ppm.

Edgerton spends about $5,000 a month to remove nitrates from drinking water. Levels have fluctuated — decreasing when land was in permanent cover through the federal Conservation Reserve Program, increasing when it was farmed. With more land back in perennial cover — and with less rain — nitrate levels have decreased from about 20 ppm to 12 ppm over the past year.

Lincoln-Pipestone Rural Water took four of its eight wells at Holland and North Holland offline in 2017 because a byproduct of its nitrate treatment had the potential to cause a different type of pollution. An experimental treatment that reduced nitrate levels to zero was discontinued because it was cost-prohibitive, and Minnesota Pollution Control Agency funding was available to help connect to the South Dakota-based Lewis & Clark Regional Water System.

Closing the four wells reduced production from the Holland water treatment plant by about 40%. Customers nearest that plant off U.S. 75 still get their drinking water from the four wells that don’t require nitrate treatment.

Some customers farther south receive water from other sources. Lincoln-Pipestone Rural Water buys water from Lewis & Clark, South Dakota’s Brookings-Deuel Rural Water System and Iowa’s Osceola County Rural Water System.

“Water keeps people in the region,” said Jason Overby, Lincoln-Pipestone Rural Water general manager.

Growth in agriculture — particularly hog operations — and in towns drives demand. LPRW connects about 50 new rural customers a year, and recently connected an entire community. Other communities with aging infrastructure or compliance concerns have expressed interest.

“Water is limited in this area,” Overby said. “It always seems we’re searching for water to meet demands of the region. It’s a hard pill to swallow … if the water that is available can’t be supplied without treatment.”

The closed wells could reopen if a cost-effective nitrate treatment emerges, or if changes on the landscape sufficiently reduce the nitrate load in the aquifer.

“What this grant is hoping to achieve is to have positive impacts before necessary treatment costs,” Overby said. “If all the producers were to participate in this and there is huge impact — the nitrogen load lessens — the benefit would be that Lincoln-Pipestone would not have to necessarily seek treatment, would not have to incur huge costs for developing a new treatment process to eliminate nitrates.”

DeBeer said she hoped the practices implemented would show a trend in nitrate reduction after the three-year grant period.

Meanwhile, Griebel said he expected neighbors to take notice.

“They are watching to see what my results are, to see if they’re going to try it or not,” he said.