A new study found 42% of southwest Wisconsin wells tested face contamination groundwater
A study of well water in southwest Wisconsin found 42% of 301 randomly selected wells in Iowa, Grant and Lafayette counties exceed federal health standards for E.coli and nitrates. A second round of testing is scheduled for the spring to determine if the contamination is likely caused by dairy or swine manure, or from faulty septic systems.
According to The Chippewa Herald, the tests were conducted in November and were searching for E.coli or nitrate bacteria, which was coordinated by nonprofit Clean Wisconsin. While in 2018 Gov. Scott Walker approved stricter standards for disposal of manure in 15 eastern Wisconsin counties with vulnerable groundwater, those rules do not apply to southwest Wisconsin.
“I was surprised that it was as high as it is,” said Lynda Schweikert, administrator of Grant County’s conservation, sanitation and zoning department. “Now I’m just interested to see what is causing the contamination.”
According to Ken Bradbury, state geologist, one of the objectives of the recent study was to answer arguments that insufficient research and monitoring have been done regarding the geography of the southern part of the state, a potential reason the new manure regulations were not extended to the south. Before the study is concluded in 2020, researchers plan to explore a variety of factors that could contribute to contamination, including soil conditions.
“The shallow bedrock and thin soils in southwest Wisconsin make this a vulnerable setting from the standpoint of groundwater contamination,” Bradbury said. “Now that we’re beginning to get some solid data sets we can begin to compare the results to physical parameters such as bedrock depth, soil type and well construction in order to determine the most important factors controlling well vulnerability.”