SARS-CoV-2 (the virus that causes COVID-19, hereafter referred to as the virus) is shed in feces by infected individuals. Virus concentrations in sewage can be measured by collecting a sample at the inlet of sewage treatment plants. This information provides a pooled indicator of the status and trends of COVID-19 infections in communities served by the treatment plant (the sewershed).
Utah DEQ is collecting samples at 42 sewage treatment plants in Utah, representing approximately 80% of the state’s population. The data from these samples provide a quantitative estimate of the average number of virus RNA gene copies entering the treatment plant and normalized to the number of people living in the sewershed. The data are updated regularly to provide additional information to public health partners regarding trends in virus prevalence in Utah’s communities.
The interactive dashboard below shows results from ongoing SARS-CoV-2 sewage monitoring in Utah along with observed infection rates in each corresponding sewershed. Points on the map represent sewershed centroids and are color-coded by trends in gene copies in sewage over the four most recent samples. Areas without markers indicate un-sampled locations. Select a location on the map to see monitoring results and infection rates for a desired sewershed.
On August 1, 2021, we moved all laboratory analyses associated with wastewater surveillance to the Utah Public Health Laboratory. There are a number of changes that could affect the end results displayed in this report, including sampling on different days, sample transportation times, RNA concentration/extraction methods, and the lab personnel running the analyses. It is extremely difficult to predict how these changes affect the results, though for at least some facilities the difference appears to be minimal. Results from some other facilities are now considerably higher. Ultimately, we expect the results post-change to be at least as accurate as previous data, if not more so.
SARS-CoV-2 viruses are shed in the feces of infected individuals. Virus concentrations in sewage can be measured by collecting a sample at the inlet of sewage treatment plants. This information provides a pooled indicator of the status and trends of COVID-19 infections in communities served by the treatment plant (the sewershed).Although the virus is unlikely to be viable or infectious at sewage treatment plants, more studies are needed to confirm this assumption. Sewage treatment systems do an excellent job of treating sewage and disinfecting viruses and other pathogens. Operators at these facilities follow appropriate steps to reduce risk of exposure to all pathogens in raw sewage.
Early in the pandemic a pilot investigation was conducted to evaluate whether or not the RNA of SARS-CoV-2 could be reliably quantified from sewage influent samples. Investigation results demonstrated that the number of gene copies could be reliably measured in the sewage of communities with known COVID-19 infections. It is currently not possible to reliably and accurately predict the number of infected individuals from sewage sample results, but the study results demonstrated higher RNA concentrations in communities with a higher density of infected patients. More importantly, the pilot study demonstrated that sewage results could be used to track trends in community infection rates, potentially providing an early warning of future outbreak events.
After seeing the pilot investigation results, Utah’s COVID-19 Unified Command requested that the wastewater epidemiology investigation be expanded statewide. It is not presently possible to measure SARS-CoV-2 RNA from every treatment plant in the state, so Utah’s DEQ and DOH selected facilities that could provide the most valuable information. Factors used to make these selections induced facility size, community susceptibility to new infections (i.e., large numbers of tourists) and the community Health Improvement Index.
Utah DEQ is working with wastewater treatment professionals to collect samples at 42 sewage treatment plants in Utah, representing approximately 80% of the state’s population. The map (“Current Data” tab) and table below shows the locations of the facilities along with the population served by each facility that will be sampled.
|Facility Name||County||Health Department||Estimated Population Served|
|Blanding||San Juan||San Juan||3,700|
|Brigham City||Box Elder||Bear River||32,000|
|Central Davis Sewer District||Davis||Davis County||58,000|
|Central Valley Water Reclamation Facility||Salt Lake||Salt Lake County||515,494|
|Central Weber Sewer Improvement District||Weber||Weber – Morgan||312,000|
|East Canyon Water Reclamation Facility||Summit||Summit County||23,304|
|Heber Valley||Wasatch||Wasatch County||24,000|
|Jordan Basin Water Reclamation Facility||Salt Lake||Salt Lake County||106,000|
|Logan City||Cache||Bear River||94,005|
|Magna||Salt Lake||Salt Lake County||28,000|
|Monticello||San Juan||San Juan||2,000|
|North Davis Sewer District||Davis||Davis County||186,000|
|Orem City||Utah||Utah County||112,901|
|Payson City||Utah||Utah County||16,000|
|Price River Water Improvement District||Carbon County||Southeast||17,312|
|Provo City||Utah||Utah County||110,000|
|Salt Lake City||Salt Lake||Salt Lake County||209,645|
|Silver Creek Water Reclamation Facility||Summit||Summit County||10,000|
|South Davis SD North||Davis||Davis County||69,000|
|South Davis SD South||Davis||Davis County||35,000|
|South Valley Water Reclamation Facility||Salt Lake||Salt Lake County||206,000|
|Spanish Fork||Utah||Utah County||41,000|
|Timpanogos Special Services District||Utah||Utah County||253,098|
|Tremonton||Box Elder||Bear River||12,451|
Samples are being collected weekly at each of the 42 facilities. If results indicate a sharp increase, additional follow-up samples will be collected within the constraints of sample capacity. In most cases, results will be made available within 3 days of sampling on the data dashboard (“Current Data” tab).
Scientists at the University of Utah, Utah State University, and Brigham Young University developed a uniform method to measure the genetic material of the virus in sewage entering treatment plants. The laboratory method includes the same processes used for most clinical COVID-19 diagnoses. Virus concentrations were coupled with wastewater flow and service area populations to estimate viral concentrations in units of SARS-CoV-2 gene copies per person per day. This metric provides an indicator of changes in community infection rates in each treatment plant’s service area.
Resources for Partners
- Jennifer Weidhaas, PhD, P.E., University of Utah
- D. Keith Roper, PhD, Utah State University
- Zach Aanderud, PhD, Brigham Young University
- Jim VanDerslice, PhD, University of Utah
- Marissa Taddie, PhD, University of Utah
- Erica Gaddis, PhD, Utah Division of Water Quality
- Jake VanderLaan, Utah Division of Water Quality
The Water Research Foundation hosted an international web conference on the detection of novel coronavirus using wastewater epidemiology. Experts discussed the promise and challenges of using this information to inform pandemic response.
Early preprints of several research papers have been released so that water and health professionals have access to the information while they undergo peer review. This includes a review of the state of knowledge of SARS-CoV-2 in wastewater and another review that calls for international coordination on these research efforts.
Several case studies provide early results for studies similar to the Utah pilot investigation and the potential for sewage monitoring as a leading indicator of COVID-19 infections including studies from: Massachusetts, Montana, Connecticut, France, the Netherlands, Australia, Spain, and Italy.
A group of Italian researchers have released the results of a study (339 KB) that affirms the conclusion of Utah’s pilot that treated wastewater poses little threat on the spread of novel coronavirus. A recent review paper reviewed all available literature on the topic and reached a similar conclusion.