DES MOINES, Iowa (WHO) — Last week, the Des Moines Metropolitan Wastewater Reclamation Authority received the highest virus concentration in a water sample since testing began in July.

The WRA was hoping that the number would remain as an outlier, but later last week, another test sample came in with an even higher virus concentration: 1,269,483 copies of the COVID-19 virus in one liter of sewage. The WRA wants the data to be used to indicate whether there will be a spike of coronavirus cases in the near future.

The Polk County Health Department uses these numbers as a tool to see what the community spread looks like at the moment.

“It is a surveillance tool and it helps us see what they are already seeing. We know that from what they are seeing that there is high transmission and we know that already,” said Nola Aigner Davis, communications officer with the Polk County Health Department.

Davis mentioned that the high numbers could be a result of Thanksgiving travel with family and friends coming in and out of the county to celebrate the holiday. Looking forward to the upcoming holiday at the end of December, the department encourages people to celebrate safely.

“If you are going to gather with your family for the holiday if you are going to travel you need to get vaccinated, you need to get your booster,” said Davis. “We can’t stress this enough you are putting yourself at risk you are putting everyone else at risk.”

The WRA releases its report publicly and can be found on its website.