Southwest Wisconsin groundwater and geology (SWIGG) study
WGNHS is working with counties in southwest Wisconsin to improve our understanding of drinking water quality. Random sampling of more than 300 private wells in this area indicates widespread contamination by bacteria or nitrate or both. Our goal is to determine how groundwater quality is related to local hydrogeologic properties and well construction.
- Project page
- Wisconsin Public Television interview about project (12m 5s)
- Hazardous drinking water found in 42% of southwest Wisconsin wells (Wisconsin State Journal article)
Natural toxins in the Tunnel City rocks
Sandstone formations that are productive drinking water sources under almost half of the state may be sources of naturally occurring groundwater contamination. Rocks known as the Wonewoc Formation and the Tunnel City Group contain lots of metals, including arsenic, cadmium, and lead. WGNHS used rock core and drill cuttings stored in our sample repository as well as hand samples from outcrops in the area to identify the elemental composition of these rock formations. This baseline data—what is in these rocks—will help future researchers determine what might end up in our drinking water.
- Geochemistry and mineralogy of the Wonewoc–Tunnel City contact interval strata (report and data)
- Tracking toxins in Tunnel City (Aquatic Sciences Chronicle)
Tracking nitrate movement in groundwater
To better maintain the integrity of Wisconsin’s groundwater supplies, the Wisconsin Department of Natural Resources wants to continuously improve the way it models nitrate movement in groundwater. They aim to create a tool to help state and local agencies, landowners, and growers in making cost-effective decisions about land-use and agricultural practices.
Survey staff are collecting the data and creating the model, starting with the water supplies for the City of Waupaca.
- Projects page (view “Wellhead protection and nitrate transport”)
- Role of nitrate contamination in Wisconsin municipal water supplies (Wisconsin Water Resources Institute story)
Determining the source of radium in Dane County’s groundwater
WGNHS is collaborating with UW–Madison Engineering to determine which rock layers are contributing radium to Dane County’s water supply wells. The deep sandstone in Wisconsin typically has higher-than-normal levels of this naturally occurring contaminant that drove the City of Waukesha to a Lake Michigan water diversion. This project team is testing wells and rock samples for our core repository in Mount Horeb to characterize which rocks, in which areas of the state, are more likely to have radium problems.
- Removing radium from groundwater (Sea Grant Institute video, 4m 40s)
Groundwater, wells, and agriculture in Bayfield County
When the Large-Scale Livestock Study Committee of Bayfield County needed basic information about groundwater and water supply wells, WGNHS prepared a map and cross sections illustrating the water resources and typical well construction in the area. This information will be used to address design, operation, and management of livestock facilities in a way that will protect water quality and the drinking water supply. The Survey was later commissioned to produce a water-table map for all of Bayfield County and, ultimately, a groundwater atlas.
- Bayfield County water-table map and water well database (report, water-table map, and GIS data for entire county)
- Groundwater and wells in agricultural regions of Bayfield County, Wisconsin (report, water-table map, cross sections, and GIS data for parts of the county)
Municipal drinking water safety: Groundwater, pathogens, and public health
Most Wisconsin municipalities disinfect their water supply. For those that don’t, viruses from untreated sewage can contaminate groundwater, causing acute gastrointestinal illness. Chlorination is one of several methods that a water utility can use to treat water to maintain drinking water safety.
Groundwater flow model for Columbia County
Residents of Columbia County rely exclusively on groundwater for their drinking water. When more than 20% of the groundwater samples from that county had nitrate concentrations higher than the drinking water standard Columbia County officials wondered where they should site their next water supply well. To help with that decision, WGNHS prepared a groundwater model that provides a tool to determine where nitrate pollution is coming from. It can also be used to guide future land use decisions.
Answering groundwater questions in the Town of Byron (Fond du Lac County, Wisconsin)
Officials of the Town of Byron became concerned about manure spreading and water quality in their area and WGNHS responded. We created a series of maps and a report on depth to bedrock, water-table elevation, groundwater recharge, and groundwater susceptibility.
Tracking viruses in deep water supply wells to protect drinking water
Since 2007, WGNHS has been working with USGS and USDA to find and study viruses in deep water supply wells. These scientists have determined the most likely source of the viruses is the city sewers but the study continues to evaluate where the systems (sewer and water supply) are leaking and how they may be interconnected. Chlorination, a standard practice for municipal water treatment, protects the drinking water supply while these scientists work to better understand the broader problems associated with the nation’s aging underground pipes and our drinking water quality. Through predictive modeling the investigators will also assess the risk of viral contamination of drinking-water supply wells.
Tracking natural arsenic to ensure drinking water safety
Groundwater in parts of Wisconsin contains naturally occurring arsenic. Geologists at WGNHS used their understanding of the regional geology, along with their review of rock cores and cuttings stored at our sample repository, to define the areas that are most affected by this problem and to recommend methods to minimize its impact on people’s water supply. WGNHS provided the science supporting specific well construction requirements and methods for the Wisconsin DNR’s Arsenic Advisory Area. These rules are working, resulting in more arsenic-free wells.
Helping a school provide arsenic-free water to its students
When Wood School in southeast Wisconsin found arsenic in its groundwater, we studied the water quality and the rock chips from nearby wells stored in the WGNHS sample repository. We concluded the arsenic occurred naturally and recommended they drill a shallower replacement well. Their water is now arsenic-free.