The Environmental Working Group report included data from the Minnesota Department of Health (MDH) regarding nitrate contamination at or above the legal limit of 10 milligrams per liter, or mg/L, set by the U.S. Environmental Protection Agency (EPA) in 1991.

Recent research indicates that half that amount — 5 mg/L, or even less — is associated with higher cancer risks and birth defects. Tests were done by water utilities in accordance with federal regulations between 2009 and 2018, according to the report.

Although nitrate is found in many foods and occurs naturally in soil at low levels, a contamination level of 3 mg/L or more indicates a human cause, according to the MDH.

The MDH recently started requiring water utilities that reached 3 mg/L, to increase testing to once every quarter instead of annually.

Minnesota Dept. of Agriculture map The Minnesota Department of Agriculture Township Testing schedule from 2013 to 2919.

Private well testing in Minnesota showed that more than 3,000 households drink from wells with nitrate contamination of 10 mg/L or higher. More than 7,600 wells testing at least once at or above 3 mg/L, 6,000 of them with nitrate of at least 5mg/L.

A number of rural Brown County wells tested by the MDH since 2009 showed some nitrate and nitrite and nitrogen levels above 5 mg/L.

Base samples from Well #1 at the Flying Dutchmen Motorcycle Club in Cottonwood Township, south of New Ulm, showed 7.8 mg/L on June 23, 2010; 7.5 mg/L on July 20, 2011; 8.1 mg/L on July 2, 2013; 6.3 mg/L on June 2, 2015; and 10 mg/L on May 26, 2016.

Since then, samples had much less of the contaminants. Base samples taken at the motorcycle club grounds on April 27, 2017; May 22, 2018 and June 6, 2019 showed less than .05 mg/L, according to the MDH.

“We need to get more information to find out why that number was high. They had a storage tank out there. If it had any fertilizer in it, it may have over-flowed. And it’s in a rock aquifer. We’re looking into it. Over the last three years, I haven’t seen anything near the high levels,” said MDH Non-community Public Water Supply Unit Supervisor Dave Hockanson.

“It (testing results) may have a lot to do with well construction and geology,” said Hockanson.

Testing near Laraway Roofing, a couple miles east of Essig, peaked at 4.1 mg/L, according to a sample taken April 20, 2009. Other high test results were 3.7 mg/L June 2, 2010; 2.7 mg/L Feb. 26, 2013; 3.8 mg/L Feb. 27, 2014; 4.1 mg/L Feb. 23, 2016 and 2.9 mg/L April 24, 2018.

Testing at Well #1 near the Sleepy Eye Golf Club Clubhouse peaked at 4.7 mg/L July 20, 2011 and 4.1 mg/L May 20, 2014.

Hockanson said other test samples with high contamination levels were 9.2 mg/L in 1997 at Beaver Falls County Park, northwest of Morton in Renville County; and 8 mg/L near Central Lutheran Church, north of Fairfax in 2008.

Nitrate levels greater than 10 mg/L, as high as 22.2 mg/L, were found in Ridgely Township, Nicollet County. Testing was done in 2018 and 2019. Results showed 19.2% of wells over the health standard of 10 mg/L. An MDA report on the tests is expected this year.

Hockanson said according to his knowledge, no nitrogen mediation work was done at any of the sites with higher contamination levels.

“Regulatory action comes in when they are above 10 mg/L. If we see a trend, we often engage folks,” Hockanson said.

Hockanson said the City of St. Peter has been very progressive in dealing with nitrogen.

“They built two reverse osmosis water treatment plants before there was a violation. The plants are expensive to build and operate,” Hockanson said.

Three southwestern Brown County townships were tested in 2019 as part of the MDA (Minnesota Department of Agriculture) Township Testing Program. Test results are expected to be released later this spring.

“The three townships were identified because they have vulnerable geology and row crop agriculture, which make them vulnerable to nitrate contamination,” said Allen Sommerfeld, MDA Senior Communications Officer.

Sommerfeld said homeowners in identified townships receive a sampling kit in the mail. Water samples are collected by the homeowner and sent to a certified lab in a prepaid mailer. If nitrate is detected in the water sample, homeowners may be offered a subsequent test for pesticides.

A trained professional will visit the homeowner to collect water samples for pesticide analysis. Program participants names, addresses and phone numbers will remain confidential, Sommerfeld said.

Minnesota’s new Groundwater Protection Rule focuses on restricting fall nitrogen fertilizer application for farmers living in areas with vulnerable groundwater or in a protection area around a public well with high nitrate.

Notification of areas subject to fall application restrictions will occur in January 2020. Restrictions take effect in September 2020.

For more details on the rule, visit www.mda.state.mn.us.

(Fritz Busch can be emailed at fbusch@nujournal.com).