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SWIGG test results announced
By David Timmerman
    “We have to let the whole study play out.”
    Lynda Schweikert, Administrator of the Grant County Conservation, Sanitation, and Zoning Department, prefaced that there is still a ways to go until the Southwest Wisconsin Groundwater and Geology Study (SWIGG) of Grant, Iowa, and Lafayette counties’ rural residential wells is complete, but the first phase of that study is now complete with an additional 539 wells having been tested this past April.
    The results of those tests? Overall, 27 percent of wells tested in April did not meet health standards for total coliform, E. coli, or nitrate, less than the 42 percent that tested positive in November 2018.  
    Sixteen percent of the samples were positive for total coliform and 2 percent were positive for E. coli. Fifteen percent of the samples exceeded the 10 parts-per-million health threshold for nitrate-nitrogen; the highest sample result was 67 ppm and the median was 3 ppm.
    The percentage of wells positive for total coliform was lower than during the first sampling event in November 2018, when 34 percent of wells were positive. Nitrate and E. coli results are similar to November when 16 percent of samples exceeded the threshold for nitrate and 4 percent were positive for E. coli.
    However, a fluctuation of numbers does not mean things improved, as the wells tested this spring were different than the ones tested in November.
    “The numbers cannot be compared, it’s an addition to the baseline data,” Schweikert stated.
    “Finding fewer coliform detections in wells tested in the early spring is consistent with what other statewide surveys have reported,” said State Geologist Ken Bradbury, Director of the Wisconsin Geological and Natural History Survey. “This may be because bacteria die off during winter and in the winter months there are fewer contamination sources on the land surface.”
    This study has provided the most robust assessment of groundwater quality in the three-county region to date.  “We now have a solid assessment of private well contamination in southwest Wisconsin based on a large, representative sample of wells,” said microbiologist Mark Borchardt, a researcher with the USDA Agricultural Research Service.
    Wells were selected randomly to minimize bias, and a large proportion of the private wells in the three counties were tested (8% of wells). The “snapshot” approach of collecting all samples at nearly the same time gives researchers greater capability to identify factors related to well contamination.
    Schweikert noted that the counties, which are covering the cost of the $170,893 study, selected outside labs to test the samples and construct the data to give an unbiased view of the conditions of water quality for rural residential wells.
    What it does is confirm there is an issue out there.
     “We can no longer say we don’t know the extent of the problem,” said Schweikert. “Now we are asking, what are the causes of contamination?”
    The possible reasons for that contamination will be given light with the second phase of the study, now underway. A subset of the wells that had shown contamination in the November and April testing periods have already been retested this spring, and will be tested again during the summer, fall and winter, to see about fluctuations in the results, as well as have additional tests to try and determine the sources of the contamination.
    Also this summer, a comprehensive well construction study will look at the design and integrity of wells across the county.
    There will also be a study of the bedrock and ground in the region.
    The goal is determining correlations between water quality, geology, and well construction and maintenance.
    Back in January, when the first numbers sent shock waves through the state, Schweikert was quick to note that no determination had been made at why wells showed contamination. Groundwater can be different in regions, more corrosive, which could cause damage to the well casing.
     Another potential issue to be investigated is if the higher amount of rain may have been part of the culprit. November was a wet month, part of a wet year, and the study is using test wells to see if rainwater going into the aquifers is exacerbating the contamination.
    Rainwater may also be pointing to another problem - improperly capped wells. If the well cap is not sealed, contaminants may have gotten in above ground, and not through some leak in the casing.
    Schweikert also said in January that there are wells in the county that were grandfathered - they met regulations when they were installed, but would not meet today’s standards.
    Since the test samples for phase one were taken by the landowner, there may have been some sort of contamination to the sample as it was being taken.
    The second phase of the study will lead more detailed information that will help in determining what may be needed to keep drinking water clean. Those results should be available around the end of 2019, or early 2020.
    For those wells that tested positive, the owners were informed and given information from the Wisconsin Department of Natural Resources on what they should do next. Things like inspect, or get their wells inspected by an expert, make sure the well is properly sealed, as well as looking into having the well ’shocked,’ or disinfected, and waiting at least a week before the next test to reduce the chances of a false negative.
    It is recommended that all private well owners test their wells annually. Residents can contact their local county health departments in Iowa, Grant, or Lafayette counties for information on testing, costs, and certified laboratories. The Wisconsin DNR also provides information and advice for well owners online at
    Insuring clean water from wells is very important, as 44 percent of residents in Grant, Iowa, and Lafayette counties receive their drinking water from the 18,000 private wells in the region (approximately 8,000 in Grant County alone).
    The study was initiated by Grant, Iowa, and Lafayette Counties in collaboration with researchers from the U.S. Department of Agriculture, the Wisconsin Geological and Natural History Survey-UW Extension, and the U.S. Geology Survey.  Support for the study comes from the counties and agencies involved as well as other organizations, including the Lafayette Agricultural Stewardship Alliance and the Iowa County Uplands Farmer-led Watershed Group.
    Schweikert was happy to see the number of people participating increased between November and April, as there were only 301 tests completed last fall. “Public participation is the most important,” Schweikert stated, thanking those who participated, as it gives a more complete picture of where things sit on rural drinking wells in the region.