Wastewater Testing and COVID-19

Testing wastewater to detect the virus that causes COVID-19 has the potential to be an early warning sign for COVID-19 spreading in our community. Wastewater test results for select Gallatin County communities can be found below. For help understanding wastewater testing and COVID-19, read the FAQs further down on this page.

Summary Information for the City of Bozeman

  • 3/23/2020 – Sample positive
  • 3/27/2020 – Sample positive
  • 3/30/2020 – Sample positive
  • 4/01/2020 – Sample positive
  • 4/03/2020 – Sample positive
  • 4/06/2020 – Under detection limit
  • 4/08/2020 – Under detection limit
  • 4/15/2020 – Under detection limit
  • 4/22/2020 – Under detection limit
  • 4/29/2020 – Under detection limit
  • 5/06/2020 – No virus detected
  • 5/13/2020 – No virus detected
  • 5/20/2020 – No virus detected
  • 5/27/2020 – No virus detected
  • 6/03/2020 – Sample positive
  • 6/05/2020 – Sample positive
  • 6/08/2020 – Sample positive
  • 6/10/2020 – Sample positive
  • 6/12/2020 – Sample positive
  • 6/15/2020 – Sample positive
  • 6/17/2020 – Sample positive
  • 6/19/2020 – Sample positive
  • 6/22/2020 – Sample positive
  • 6/24/2020 – Sample positive
  • 6/26/2020 – Sample positive
  • 6/29/2020 – Sample positive
  • 7/1/2020 – Sample positive
  • 7/3/2020 – Sample positive
  • 7/6/2020 – Sample positive
  • 7/8/2020 – Sample positive
  • 7/13/2020 – Sample positive
  • 7/15/2020 – Sample positive
  • 7/17/2020 – Sample positive
  • 7/20/2020 – Sample positive
  • 7/22/2020 – Sample positive
  • 7/24/2020 – Sample positive
  • 7/27/2020 – Sample positive
  • 7/29/2020 – Sample positive
  • 8/5/2020 – Sample positive
  • 8/12/2020 – Sample positive
  • 8/19/2020 – Sample positive
  • 8/26/2020 – Under detection limit
  • 9/2/2020 – No virus detected
  • 9/9/2020 – Sample positive
  • 9/16/2020 – Sample positive

Wastewater samples are collected at the Bozeman Water Reclamation Facility (BWRF) that receives and treats domestic, commercial, and industrial wastewater from the City of Bozeman, Montana (USA). RNA isolated from the wastewater is tested for SARS-CoV-2 (novel coronavirus that causes COVID-19) using diagnostic kit developed by the US Centers for Disease Control and Prevention. The test detects two distinct regions of the nucleocapsid (N) gene from SARS-CoV-2 genome (i.e. N1 and N2). Samples that result in both N1 and N2 above the detection limit are considered positive, while detection of only one region (N1 or N2) or testing below the detection limit is considered negative. Temporal dynamics of SARS-CoV-2 RNA (line graph) is superimposed on the epidemiological data (bar plot). Bars represent number of patients who reported symptom onset on the specified day.

We are grateful to Josh French, Justin Roberts, and the other dedicated wastewater technicians at BWRF that made this work possible.

Summary Information for Big Sky Water & Sewer District #363

Summary Information for the Town of West Yellowstone
Summary Information for the City of Three Forks

Wastewater viral load data are being provided to the Gallatin City-County Health Department by the Wiedenheft Lab at MSU for the Bozeman location and from the Walk Lab at MSU for the Big Sky and West Yellowstone locations. Visual representations and publication information are available on the MSU lab sites.

Wastewater Testing FAQs

The wastewater testing that has been completed so far tells us at least two key pieces of information:

  1. Finding the virus in wastewater has either come just before or at the same time as new confirmed cases in Bozeman, West Yellowstone, and Big Sky. This gives us information about where the virus is and where it is spreading. For example, if the virus is found in wastewater in towns with no confirmed cases, this could mean that new cases will soon appear. In towns where no virus is found in the wastewater, this could mean that few people, if any, are infected in the community.
  2. Wastewater testing also shows whether viral levels in wastewater are going up, staying the same, or going down from week to week. For example, decreasing virus levels in wastewater seems to be linked with decreasing numbers of new confirmed cases in Bozeman and West Yellowstone.

Please note that testing results will only represent the people in a community who use the wastewater system. This means that wastewater results will not be able to predict all new confirmed cases.

Wastewater test results are submitted to Gallatin County. They are also available to the public online on this page, at the Wiedenheft Lab at MSU and from the Walk Lab at MSU.

COVID task force members, the health department, and the health officer will use these test results, along with many other pieces of information, to make public health decisions.

Wastewater testing is one promising piece of the complex COVID-19 puzzle. We’re still learning a lot about this new virus, how it spreads, and how all of our actions impact the number of new confirmed cases.

These test results are a promising tool to help make our community safer. By pinpointing COVID-19 hotspots, we can direct resources that protect vulnerable populations more efficiently.

Wastewater is collected using an “autosampler.” This is a special pump that pulls water at set intervals over a 24-hour period. The sample is called a “composite” sample because it represents many individual samples.

Or, what is N1 and N2?

Viruses are complex living things made up of genetic material. The virus that causes COVID-19 is called SARS-CoV-2. One of the genes in SARS-CoV-2 is called the “nucleocapsid.”

‘N1’ and ‘N2’ simply refer to two locations in the nucleocapsid gene. When we test for SARS-CoV-2, we are trying to identify these two locations. Having two locations instead of just one makes the test more reliable.

Ct stands for “cycle threshold”. Essentially, it represents the amount of virus in the sample. The higher the Ct number, the lower the amount of virus.

If there are a lot of SARS-CoV-2 viral genomes in the sample (N1 and N2 locations), it is found rather quickly. If there are few viral genomes in the sample, it will take longer to find.

When virus is found in a sample, we try to estimate how many viruses are present. This helps us understand whether viral levels found in wastewater are going up, staying the same, or going down from week to week.

When we report the results, we calculate the number of viruses found in a wastewater sample. They are reported as genomes per liter.

  • Funding for wastewater testing in Big Sky County Water and Sewer District #363 is provided by an award from the Big Sky Relief Fund, a response effort from the Big Sky Resort Area District, Yellowstone Club Community Foundation, Moonlight Community Foundation, and Spanish Peaks Community Foundation. Testing is funded through December 2020.
  • Funding for wastewater testing in the Town of West Yellowstone is provided by the Gallatin County Commission through September 2020.
  • Funding for wastewater testing in the City of Three Forks is provided by the Gallatin County Commission through December 2020.
  • Funding for wastewater testing in the City of Bozeman is provided by the Bozeman City Commission through August.

Testing would not be possible without the help and expertise of the engineers, operators, and management of our public wastewater systems. Thank you to the Engineer/Operator and to the General Manager of the Big Sky County Water and Sewer District #363, to the Wastewater Superintendents, operators and foremen in the cities of Three Forks and Bozeman, and to the Superintendent of Water and Sewer in the Town of West Yellowstone.


Governor's Face Covering Directive
COVID-19 printable resources
Governor Bullock's Reopening MT phased approach
Governor Bullock's Guidelines and Considerations for Reopening Businesses and Schools
Governor Bullock's Guidelines and Considerations for Reopening Businesses and Schools