COVID-19: Wisconsin Wastewater Monitoring Program

What does this program do?

The Wisconsin Wastewater Monitoring Program tests samples of wastewater across the state to track levels of SARS-CoV-2, the virus that causes COVID-19. This project is a collaboration between the Wisconsin Department of Health Services (DHS), Wisconsin State Lab of Hygiene, Milwaukee Health Department Lab, and the University of Wisconsin-Milwaukee.

Why are we monitoring wastewater?

Wastewater testing is an important tool for tracking levels of COVID-19 in a community. For people with COVID-19, the virus can be detected in their feces shortly after they are infected with the virus. It can be detected even before they experience symptoms, or if they are infected but asymptomatic. We test wastewater collected from municipal wastewater treatment facilities to measure the amount of the virus present in each sample. This tells us how widely COVID-19 is spreading in the community. Tracking these levels over time allows us to alert communities when levels are rising so that they can act quickly to prevent further spread of COVID-19. 

Wastewater monitoring has been shown to be an accurate, reliable, and cost-effective program. It is now one of the best tools we have for monitoring COVID-19 activity in Wisconsin and the U.S. Read more about our decision to incorporate wastewater testing into our COVID-19 surveillance below.

How does wastewater monitoring work?

The Wisconsin State Lab of Hygiene, Milwaukee Health Department Lab, and University of Wisconsin-Milwaukee analyze wastewater samples from wastewater treatment facilities across Wisconsin to determine the amount of SARS-CoV-2 virus present in untreated wastewater. Most facilities send in two samples per week, although this number ranges from one to six depending on the site. When tracked over time, the amount of virus, measured as viral gene copies, can indicate if COVID-19 activity is increasing or decreasing in a community.

How can monitoring wastewater improve public health?

Wastewater monitoring can:

  • Serve as an early warning of increasing COVID-19 activity in communities.
  • Inform the public of current COVID-19 levels in their community so that they can take steps to avoid COVID-19, particularly at times of high transmission.
  • Alert health care providers about increasing COVID-19 levels so they can prepare for expected surges.

Where is wastewater monitoring being done?

Wastewater treatment facilities across Wisconsin collect and submit wastewater samples to the Wisconsin Wastewater Monitoring Program. This includes both large and small cities (sample sites are shown in the map below). The current wastewater treatment facilities serve approximately 50% of Wisconsin's population. Wastewater monitoring does not include individuals on private septic tanks or those connected to non-participating wastewater treatment facilities.

Select a location from the list or map below to see wastewater monitoring results for each sewershed, or check the statewide average to see the results for all of Wisconsin.

Visit CDC’s (Centers for Disease Control and Prevention) National Wastewater Surveillance System dashboard to view regional and national wastewater trends for COVID-19. Note that CDC’s “viral activity levels” use a different scale than presented on the Wisconsin COVID-19 wastewater dashboard, so levels may not be directly comparable.

The Wisconsin Wastewater Monitoring Program also tracks COVID-19 variants found in wastewater. For additional information about COVID-19 variant tracking conducted in Wisconsin wastewater, please visit the Wisconsin State Lab of Hygiene's SARS-CoV-2 Wastewater Genomic Dashboard.

Acronyms used on this dashboard

MSD = Metropolitan Sewerage District; WWTF = Wastewater Treatment Facility; WWTP = Wastewater Treatment Plant; WPCC = Water Pollution Control Center; WPCF = Water Pollution Control Facility; MGC = Million Gene Copies

Please use the latest version of Google Chrome, Mozilla Firefox,Microsoft Edge, or Apple Safari to view this visualization.

Note: On June 29, 2024, a laboratory change was implemented for four sites: Brookfield (Fox River), De Pere, Green Bay, and Racine.
This laboratory change will result in higher levels of COVID-19 displayed on the dashboard for these 4 sites after June 29, 2024. Do not compare levels at these sites from before and after this change (see grey vertical bar on graph). In the long-term, this change will mean all sites use the same testing method, which will improve the consistency of our wastewater data.

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Last revised August 22, 2024