Nitrogen application (copy)

Groundwater contamination by nitrate is tied mainly to agricultural fertilizers.

Contributed

Sometimes, really important news just doesn’t get much attention.

Consider the case of nitrate, primarily tied to agricultural fertilizers, and the 2017 report by the Wisconsin Groundwater Coordinating Council. The council is comprised of state agencies with responsibilities for groundwater management, plus a governor’s appointee.

The section of the report devoted to nitrate in groundwater is alarming to say the least, but the report went almost unnoticed. Maybe that’s because nitrate contamination is nothing new. What is new is research linking the water-soluble molecule to an array of health concerns.

There’s growing evidence of a correlation between nitrate and diabetes, the report notes. Birth defects have also been linked to nitrate exposure. While more research is needed on birth defects, “These studies collectively indicate an ongoing need for caution in addressing consumption of nitrates by pregnant women,” the report says.

It goes on to note that in the human body, nitrate can convert into compounds “which are some of the strongest known carcinogens.” As a result, health concerns related to nitrate-contaminated drinking water include “increased risk of non-Hodgkin’s lymphoma, gastric cancer, and bladder and ovarian cancer in older women.”

The health-based enforcement standard and maximum contamination level (MCL) for nitrate in public wells is 10 parts per million (ppm). This number was set because of concerns about another health issue, so-called blue baby syndrome, in which infants exposed to nitrate are deprived of oxygen. Some brush off this concern and advocate for a higher threshold. Given the information in the 2017 report, maybe we should go the other direction.

Where is all the nitrate coming from? About 90 percent of the nitrogen that reached groundwater in the state can be traced to agriculture, primarily manure and commercial fertilizers, the report says.

It notes that nitrate contamination of groundwater is increasing in extent and severity. Interestingly, the Department of Natural Resources website makes note of the report but instead cherry-picks declining nitrate counts in some counties as a trend.

The report, meanwhile, is quite clear about this. A 2012 survey of Wisconsin municipal water systems showed that 47 of the state's 611 municipal systems had raw water samples exceeding the maximum contaminant level. That compares to 14 systems in 1999. About 10 percent of private well samples exceed the limit, although at least a third of the 850,000 private wells haven’t been tested. In some highly cultivated regions, up to 30 percent of samples exceed the limit.

Municipal systems spent more than $32.5 million to mitigate nitrate contamination in 2012, up from $24 million in 2004. Private well owners, meanwhile, only qualify for well compensation funding if the level exceeds 40 ppm — though the health standard is 10 ppm — and the water is used for livestock. Does this seem odd?

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One strategy the state uses to reduce contamination is to encourage farmers to develop and implement nutrient management plans. Almost a third of the agriculture land in the state is covered by these plans, which is good. The state provides free resources and training to help farmers. Unfortunately, several studies indicate that nutrient management plans are “questionably effective at reducing nitrate levels to below the MCL,” according to the report. That said, the report added that broader adoption of the plans would reduce excess nitrogen applied to fields, an amount estimated at 200 million pounds in 2007.

The state began a program in 2012 to reduce nitrate levels by stressing efficiency in agricultural production. But given the serious bent of this report, more should be done. A simple way to put a dent in amount of excess nitrogen reaching groundwater would be to tie agricultural tax breaks such as use valuation to implementation of nutrient management plans.

But don’t hold your breath, given the strength of the agriculture lobby. So municipal treatment costs will rise. And if your private well is contaminated, you’re out of luck, unless you feed livestock.

Bill Berry of Stevens Point writes a semimonthly column for The Capital Times. billnick@charter.net

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