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Nitrate pollution in drinking water: What can be done?

Glass filled with drinking water from tap, isolated on the white background, clipping path included.1 / 4
This map illustrates the location of private wells constructed since 1991 with nitrate concentrations between 3 and 10 mg/L or above 10 mg/L at the time of construction. This information was released in the Minnesota Department of Health's annual report on drinking water.2 / 4
This map illustrates the results of initial testing completed in 2016. The final report for the six townships selected for the MDA's Township Testing Program will be available in 2018.3 / 4
The initial 2016 results from private well testing in six townships are summarized in this table from the Minnesota Department of Agriculture.4 / 4

The League of Women Voters (LWV) Park Rapids Area invited Chris Parthun, principal planner with the Minnesota Department of Health, to discuss management of nitrates in drinking water.

Parthun spoke Oct. 2 at Itasca State Park.

"As we know, in the Mississippi watershed there are too many nutrients that get into the Mississippi, and that creates problems for cities downstream, like Minneapolis and Dubuque, and for the Gulf," said Gretchen Sabel, chair of the LWV Upper Mississippi River Region Inter-League Organization. "There's also problems when nitrate gets into groundwater, especially because people across Minnesota and the Midwest drink groundwater with no treatment, so we need it to be clean and wholesome for consumption."

The Upper Mississippi River Region Inter-League Organization, which includes LWV leagues from Illinois, Iowa, Minnesota and Wisconsin, has one mission: Make the Mississippi River clean and healthy.

Sabel was a long-time employee of the Minnesota Pollution Control Agency, but has since retired.

Parthun noted that water quality monitoring is split between three state agencies: Minnesota Department of Agriculture, Minnesota Pollution Control Agency and Minnesota Department of Health.

"In Minnesota, drinking water is regularly tested for contaminants," he said. "Samples are analyzed right here in Minnesota laboratories and public water suppliers are required to do this quarterly and annual reports are given to recipients of that drinking water. It's called a consumer confidence report."

There are more public water supply wells in the state than the oft-quoted 10,000 lakes. These 11,000 wells serve 4.2 million people.

Groundwater is the source for 98 percent of public water supply systems and 75 percent for citizen's private wells, Parthun said. The remaining 25 percent of citizens drink surface water.

Consumer confidence reports are available for public viewing.

"That will tell you a broad sweep of chemicals, probably up to 150 different parameters that are tested. Very in-depth because it's a public water supply that serves a large population," Parthun said.

Private wells must meet state health standards for nitrates, bacteria and arsenic.

"Interestingly, no additional testing or treatment is required. Once you pass that initial test, there's no requirement that you follow-up with any additional testing of that private well. That's the responsibility of the landowner," Parthun said.

Geological conditions throughout the state "are extremely important because they dictate the water quality."

The depth to bedrock is "quite deep" in central Minnesota's sand plains, where Park Rapids sits.

"That tells me there's a lot of area for water supply to be captured and available for consumption," Parthun said, adding it's also sensitive to groundwater contamination.

Nitrate (NO3) is a naturally occurring chemical made of nitrogen and oxygen. Nitrate is found in air, soil, water, and plants. Much of the nitrate in the environment comes from decomposition of plants and animal wastes. People also add nitrate to the environment in the form of fertilizers.

Nitrate is one of the most common groundwater pollutants found in rural areas.

Increasing nitrate levels, along with high iron and manganese levels, necessitated a new water treatment facility, a new well and sealing of old wells in the City of Park Rapids about three years ago. The MPCA estimates the capital cost per household at $3,100.

According to the MPCA, pollution from nonpoint sources ­— storm sewers, failing septic systems, and runoff from construction sites, animal feedlots, paved surfaces, and lawns — contribute huge quantities of phosphorus, bacteria, sediments, nitrates, and other pollutants to water.

"Nonpoint sources represent the largest combined threat — almost 86 percent of the state's water pollution comes from non-point sources," Parthun said. "Non-point is really the driver for the nitrate levels we're seeing in the state."

In the southern half of Hubbard County, six townships were selected for the Minnesota Department of Agriculture's Township Testing Program "because they were vulnerable to contamination," Parthun said.

The MDA and Hubbard County Soil & Water Conservation District partnered to complete free nitrate testing of private wells in Badoura, Crow Wing Lake, Henrietta, Hubbard, Straight River and Todd townships. The initial sampling began in 2016. They tested 1,106 wells, with 10.5 percent exceeding the human health standard of 10 milligram per Liter of nitrate in drinking water.

The MDH is also concerned about new, emerging contaminants, such as pharmaceuticals, industrial effluents, pesticides, personal care products that are washed down drains and run through water treatment plants, he added.

"Since 1950, we have, as a society, made 5 million new chemicals that did not exist prior to 1950. Every year, we add 500 more to that list. How can we determine the health risk associated with those chemicals? It's almost impossible," Parthun said.

The Environmental Protection Agency has set regulatory standards for only 94 contaminants. Only 12 have been added in the last 20 years. Again, consider the math. That's a very small portion," Parthun said.

Viruses can live up to a year in effluent and migrate into groundwater as well.

Katie DeSchane, the communication/outreach specialist for Toxic Taters, also spoke briefly Saturday.

Her organization is concerned about pesticide use on area potato fields and the effect on human health, particularly children. During the growing season, pesticides are sprayed every 5 to 7 days, she said, adding that this type of non-point source pollution is not monitored and remediation is voluntary.

LWV is a non-partisan volunteer organization whose mission is to encourage informed and active participation in government.

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