Weekly Trends by Wastewater Treatment Facilities

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Last updated: 2/7/2023

Wastewater treatment facilities participating in the CDPHE Wastewater Surveillance Program submit two samples per week. A statistical time series model is used to determine the trend of SARS-CoV-2 viral concentrations for each individual facility for the date each sample is collected. We review these trends and classify the trend category for utilities each week. The count of utilities is listed next to each trend category, which is determined based on the criteria described within each expandable section.   

A steady increase means the viral concentrations of the two most recent samples reflect a statistically significant increase relative to earlier samples from that facility.

 

A simple increase means the viral concentrations of one out of the two most recent samples reflects a statistically significant increase relative to earlier samples from that facility.

 

A simple decrease means the viral concentrations of one out of the two most recent samples reflects a statistically significant decrease relative to earlier samples from that facility.

Wastewater treatment facilities without two recent samples (within the last 15 days) OR facilities without enough samples to construct a trend model (< 5 samples in 3 weeks) are categorized as insufficient data.

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Note: Trends are calculated with the SARS-CoV-2 viral concentration data from each individual facility; raw viral concentration levels cannot be compared between utilities due to the variability in collection time, influent flow rates, and differences in the size and characteristics of resident populations, among other factors.