With the arrival of spring, "brown water" has returned to some private wells in Calumet County — and for a longer period than usual.
"Brown water" is a term used by local residents to refer to water discolored by sediment and very likely contaminated with nitrates or bacteria harmful to human health.
Monitoring those incidents this year is Danielle Santry, the water resource specialist in the county's Resource Management department. At a program on mapping the soil depth to bedrock sponsored by Wisconsin's Discovery Farms project, she outlined some of the incidents of this spring.
By the second week of March, "brown water" was coming from the wells where this happens for about a week nearly every year, Santry said. But it lasted for up to five to six weeks in some cases this year and happened for the first time in 10 years with a few other wells.
Tests of the water were positive for coliforms (E. coli), which can come from animal or human waste, she said. According to a report at the April meeting of the Calumet County board of supervisors, the "brown water" incidents were centered in the Kloten area in the town of Stockbridge.
Other attendees at the meeting at which Santry spoke noted that similar incidents had occurred this spring in Fond du Lac, Green Lake and other counties and as early as January, following a rainfall, near Cooperstown in northern Manitowoc County.
In trying to track the source of the prolonged "brown water" outbreak this spring in Calumet County, Santry said no direct link has been identified. No one in the area was aware of any livestock manure applications on the snow-covered landscape during the winter or early spring.
It's possible that the unusually short period in the autumn of 2013 between the completion of crop harvests and the onset of winter was a contributing factor, Santry suggested. She and Discovery Farms co-Director Eric Cooley noted this left a narrow window for manure applications, perhaps setting up the conditions that led to "brown water" several months later.
Another possibility is that the deep penetration of the frost during the past winter also played a role, she said. What is known is that the affected area has fractured bedrock, which allows the rapid downward flow of surface waters, with little or no filtering of contaminants, to the aquifer from which well water is drawn.
Some, but certainly not all, surface entry points, such as sinkholes in region's karst topography, are known and have been identified. For that reason, Santry asks landowners and other parties to continue looking for spots on the land surface where surface waters tend to disappear quickly so remedial practices can be undertaken to divert those waters.
Abandoned wells that have not been properly closed can be other entry points, she added. Among the contributors of contaminants are agriculture, septic systems and possibly quarrying.
That private wells in Calumet County have frequently been contaminated with either excessive nitrates or bacteria has been well documented, Santry said. More than 3,000 water samples taken from about 1,550 wells of the total of more than 4,000 in the county have been tested since 2004.
Cooperators with the county on the testing have been the laboratories at the University of Wisconsin at Stevens Point and Green Bay and, for pesticide detection, the Wisconsin Department of Agriculture, Trade and Consumer Protection.
She is also aware that some well owners arrange for private tests. A few well owners have discontinued testing because the results have tended to be virtually the same for all previous tests.
In recent years, the average number of samples taken and tested throughout the year under the county's program has been close to 200, Santry reported. In the town of Chilton, which pays for the testing costs, about 60 well owners participate every year.
The county department strives to set up a testing program in two additional townships per year.
In breaking down the testing results to two periods of five years each, Santry observed that the contamination percentages have been dropping somewhat. Of the water sample tests conducted from 2009 to 2013, there were 34.5 percent with nitrate levels above the 10 parts per million that is considered safe for human consumption, especially by pregnant women and infants.
Although this is down from 42.4 percent for the 2004-2008 period, the overall presence of nitrates in the tested samples has been increasing, she added. The percentage of samples with nitrates higher than the 2 ppm that is considered to be a natural background amount has been 74 and 76 for the two periods.
For the two periods, water samples containing bacteria have been 30.6 and 24.7 percent respectively. E. coli was found in 5.3 percent of the samples tested for the 2009-2013 period.
As a whole, this meant the water collected for the testing was considered to be unsafe 55 percent of the time for the first five years and 47 percent of the time for the second five years.
Regarding potential remedies, Santry listed educational outreach that would get farmers to be more conscious of where they apply manure and at what volumes, and to have septic system owners be on a maintenance schedule of every two or three years. A few landowners are refusing to have manure applied to their fields while others are also setting limits, she noted.
Santry also mentioned the possibility of employing new technology that would provide closer looks at the depth of soil to bedrock and possibly identify unknown direct downward flow conduits on the landscape.