University of Wisconsin - Extension

MADISON, Wis. — Fourteen percent of 152 well water samples showed unsafe nitrate levels in a screening conducted by the University of Wisconsin-Extension at 2003 Farm Technology Days. Nitrate-nitrogen greater than 10 milligrams per liter (mg/L) of water is considered unsafe.

The high nitrate samples came from ten different Wisconsin counties. People from 28 Wisconsin counties brought water to be checked to this year — s event in Waupaca County. The average nitrate value found was 5 mg/L; the highest was 35 mg/L, more than three times the safe limit. Forty-four percent of the samples had low nitrate levels of 2 mg/L or less.

The percentage of samples with unsafe nitrate levels was nearly the same--13 percent--last year, when the show was held in Richland County in Southwestern Wisconsin. The average level was 5 mg/L for samples submitted last year.

"We're looking at such a small number of samples that it's hard to draw many conclusions from this data," said Chris Mechenich, UW-Extension groundwater educator. Wisconsin has approximately 800,000 private wells. "Still, we can say that a number of people who brought their water to us did have water that was unsafe for infants and for unborn children."

Some of the people testing their water were unaware that their nitrate levels were high, Mechenich said. Nitrate in drinking water cannot be tasted or smelled. "In fact, some people with high nitrate water tell us their water is very good tasting," she said.

High levels of nitrate in drinking water can cause "blue baby" disease in infants less than six months of age, according to Mechenich. Women who are trying to conceive or who are pregnant should not drink water with high levels of nitrate because some researchers believe it increases the risk of birth defects and miscarriages.

People without infants in their homes should also be concerned about elevated nitrate levels. Recent studies in Nebraska and Iowa have suggested links between high nitrate drinking water and cancer. High nitrate levels do not occur naturally in Wisconsin's groundwater, so they indicate that some human activity is contaminating the water, Mechenich said.

Lawn and crop fertilizers, manure storage and application, compost piles, on-site wastewater treatment systems and feedlots can contribute to nitrate levels in groundwater.

"In Wisconsin, nearly 100,000 private wells may contain unsafe levels of nitrate," Mechenich adds. To get a better idea of the extent of nitrate problems in private wells around the state, she advises checking the Center for Watershed Science and Education's groundwater web site at http://www.uwsp.edu/cnr/gndwater/privatewells/nitrate_percent.PDF.

Although information is incomplete about the long-term effects of high nitrate levels on adults, identifying nitrate in water should motivate homeowners to identify the source, and other possible groundwater contaminants from that source. In some cases, homeowners will need to repair or replace their well to solve nitrate problems. In other cases, a water treatment device can bring nitrate down to acceptable levels. Mechenich urges homeowners to choose a device certified by the Wisconsin Department of Commerce to remove nitrate or any other contaminant identified in the water. "However, what we'd really like to accomplish is to implement land management strategies that will prevent nitrate problems in the first place," she said.

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http://www.uwex.edu/ces/news

File: Health/Safety, Environment, Rural Issues, Water