A masked woman walks by the end of an alley on Exchange Street in Portland on Tuesday, Dec. 28, 2021. Credit: Troy R. Bennett / BDN

Portland and neighboring Westbrook continued to report increasing concentrations of COVID-19 in wastewater this week while levels in some other parts of the state evened out or dropped.

The uptick around Maine’s largest city comes as COVID-19 hospitalizations have surged in the state, with 136 people hospitalized with the virus as of Wednesday compared with 100 a week prior. Levels of COVID-19 in wastewater are generally seen as a leading indicator of cases and hospitalizations, suggesting Maine may not be past a recent surge driven by a more contagious strain of the omicron variant.

The Portland area had been reporting lower concentrations of wastewater than other sites in the state. But concentrations of the virus as measured in Portland’s East End sewage processing plant and the nearby Westbrook-Gorham site rose markedly in the past week, according to data published by the Maine Center for Disease Control and Prevention and Biobot.

At both sites, COVID-19 wastewater concentrations are approaching levels similar to what was seen in early February. Concentrations remain lower than peaks recently seen at sites in other parts of the state, including Bangor. They are still in the worst 5 percent nationally in terms of measurements reported by Biobot in the past six weeks.

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The continued rise shows no part of Maine is immune to the recent surge. While measurement sites in Belfast and Brunswick showed marked drops in COVID-19 wastewater concentrations in recent data after rising earlier in the month, levels have remained high in municipalities such as Augusta and Machias, the data show.

Wastewater virus levels have remained highest in Aroostook County, which has reported among the worst virus concentrations not only in Maine but in the entire U.S. on several occasions in recent months. The official seven-day case rate in the County was 82 percent higher than Maine’s overall case rate as of Wednesday, Maine CDC data show.