Wastewater Monitoring: Statewide Wastewater Respiratory Summary

This interactive dashboard includes the following sections:

Description	Section
A legend for SARS-CoV-2 with concentration levels categorized by color. See definition and methods below for more information.
A legend for influenza and RSV with concentration levels categorized by color. See definition and methods below for more information.
The calculated statewide average levels of influenza A, influenza B, and RSV. These value is displayed with text and color.
A statewide map of current levels of influenza A, influenza B, or RSV color coded to match each location's latest weekly category.

Categorizing wastewater levels of SARS-CoV-2

For each location

The colored circles on the dashboard (SARS-CoV-2 concentration categories) show the category of SARS-CoV-2 levels in each location (very low to very high). Each location represents a wastewater treatment facility partner sending weekly wastewater samples to the Wisconsin Wastewater Monitoring Program. Categories are calculated by averaging the SARS-CoV-2 concentrations of the three most recent samples at a given facility, and comparing this current level to past levels measured at that facility. Levels are sorted into five categories:

• Highest 20% (very high)
• 60th - 80th percentile (high)
• 40th - 60th percentile (moderate)
• 20th - 40th percentile (low)
• Lowest 20% (very low)

The current category displayed on the dashboard for each site indicates how recent levels at that facility compare to the historical range of concentrations from that facility.

For the state

The statewide average is calculated with the following formula:

For each site, the average SARS-CoV-2 concentration is calculated over the past seven days. This weekly average uses a rolling geometric mean of all samples at that site from the past seven days normalized to the flow rate and population size of the community.

A statewide average for each day is then calculated using the geometric mean of all sites combined.

The most recent data is then compared back to all data since February 1, 2022 and assigned a category from the following:

• Highest 20% (very high)
• 60th - 80th percentile (high)
• 40th - 60th percentile (moderate)
• 20th - 40th percentile (low)
• Lowest 20% (very low)

The most recent category is displayed on the dashboard.

Categorizing wastewater levels of influenza and RSV 

For each location

When a wastewater sample is tested for a given virus, the test shows how much viral ribonucleic acid (RNA) displayed as gene copies per liter of sewage, is present in that wastewater sample. These levels (called raw concentration) are “normalized” to adjust the final value for the number of people in the population and the amount of sewage that flows through that facility each day. For communities that send multiple samples each week, the average concentration of each virus in each community across those samples is calculated for the week. Each community’s weekly average is compared to its baseline levels (the range of all levels measured from a given site using the current laboratory method), and is assigned one of the following categories:

• 67th-100th percentile (high)
• 33th-66th percentile (moderate)
• 1th-33th percentile (low)
• 0 (not detected)

For the state

A numeric score is assigned to each facility’s weekly category:

• High = 3
• Moderate = 2
• Low = 1
• Not Detected = 0

These scores are averaged across all locations, weighted by the number of people served by each treatment facility. The final average score is rounded and converted back into a statewide category using the same scale as above. This ultimately gives a population-weighted summary of influenza A, influenza B, and RSV levels across Wisconsin for the most recent week of wastewater data available.

The statewide average levels of influenza A, influenza B, and RSV shown on this page indicate the current level of these viruses, averaged across all sites in Wisconsin, compared to past average levels measured across Wisconsin. Comparison to historical levels began in the 2023–24 respiratory season. Wastewater virus levels often vary within Wisconsin (across locations); visit the influenza and RSV dashboard to view more wastewater data.

The statewide average level of SARS-CoV-2 represents all sites in Wisconsin. This is calculated as the average amount of SARS-CoV-2 virus in the wastewater among participating sites over the past seven days. The average is then assigned a category based on data ranging from February 1, 2022 until present day.

Wastewater levels should be interpreted alongside other established public health data (see DHS Respiratory Dashboard) in order to provide a complete picture of respiratory disease activity in Wisconsin.