ESCANABA — The amount of detectable DNA from the virus responsible for COVID-19 in Escanaba’s sewer water is declining, mirroring a trend seen in the majority of the state.

According to the Sentinel Wastewater Epidemiology Evaluation Project (SWEEP), a state-run program that tracks the amount of detectable viral DNA in select sewersheds across Michigan, the 15 day trend for Escanaba is declining at a rate of 10% to 99%. The decline follows a slow increase in viral activity that stretched back to late February.

The last two samples submitted to SWEEP by the Escanaba Wastewater Treatment Plant, dated March 18 and March 20, contained more viral DNA than 36% and 14% of all samples from the site, respectively. There are many reasons why the two samples collected last week could be 22 percentiles apart, and differences between two consecutive samples like the one between March 18 and March 20 are not uncommon.

Prior to the last two samples, the plant submitted a sample with 19% more DNA on March 13, one with 24% more DNA on March 11, one with 27% more DNA on March 6, and one with 14% more DNA on March 4. When averaged, this follows the trend data, suggesting a slight increase in cases that is now beginning to wane.

Only 20 sewersheds participate in SWEEP, but Escanaba’s gently-falling trend seems to be consistent with data From across the state. Only the Holland Wastewater Treatment Plant (North), the Kalamazoo Wastewater Treatment Plant, and the Petoskey Wastewater Treatment Plant report increases in viral activity.

The Portage Lake Wasterwater Treatment Plant, the only other participating treatment plant in the U.P., shows a 15-day trend identical to Escanaba’s trend.

While data collected through SWEEP serves as a good barometer of whether viral activity is increasing or decreasing in the area, it is impossible to know the exact number of COVID-19 infections in Escanaba or the severity of cases based on the SWEEP data alone.

At the start of the pandemic, prior to the rise of at-home testing, all tests were conducted in healthcare settings or at dedicated testing sites. That data was reported to the state for tracking, but there is no requirement — or mechanism — to report home test, which now represent the bulk of all tests.

Despite the hole in the data caused by the prevalence of home tests, the Michigan Department of Health and Human Services still tracks cases and deaths based on tests conducted by healthcare providers. The most recent MDHHS case data from the week of March 23 is shown below.

Gogebic – 5

Ontonagon – 1

Houghton – 11

Keweenaw – 0

Iron – 2

Baraga – 4

Dickinson – 3

Marquette – 16

Menominee – 4

Delta – 7

Alger – 0

Schoolcraft – 1

Luce – 2

Mackinac – 1

Chippewa – 5

It is important to note that the number of cases reported by MDHHS is the number of new cases. Cases that were identified in the prior week but are still active are not reported in the data.

No new deaths were reported in the peninsula for the week of March 23 by MDHHS.