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Coronavirus levels fall in Boston area waste water, new readings show

The Deer Island Wastewater sewage treatment plant in Boston.David L. Ryan/Globe Staff

Coronavirus levels in waste water in the Boston area fell sharply last week, according to new data from the Massachusetts Water Resources Authority, an encouraging sign after COVID levels climbed during the holidays.

The new data on Wednesday showed a seven-day average of 1,501 SARS-CoV-2 RNA copies per milliliter of waste water from the southern system as of Tuesday, a 25 percent decrease from Jan. 5, when the average peaked for the holiday season at 2,009 copies/ML. The northern system, which includes waste water from the city of Boston, had a seven-day average of 986 copies/ML on Tuesday, down more than 50 percent from 2,023 copies/ML reported Jan. 1, according to the data.


The water samples are taken from the MWRA’s Deer Island sewage treatment plant three to seven times per week and are analyzed by Biobot Analytics of Cambridge, according to the MWRA website. The data serves as a tool in assessing the local prevalence of the virus and can signal changes in trends ahead of hospitalization or case count reports.

Meanwhile, on Wednesday, the Boston Public Health Commission announced a new initiative to closely track and publicly release coronavirus wastewater data specific to the city’s neighborhoods. The new program uses samples from 11 testing sites across the city in Brighton, Back Bay, Charlestown, Dorchester, East Boston, Hyde Park, Jamaica Plain, Mattapan, Roslindale, Roxbury, and South Boston.

“This data will enable BPHC to respond to the COVID-19 pandemic with more precise interventions for communities with high or rising levels of virus,” the Boston Public Health Commission said in a statement.

The data released Wednesday only goes through Jan. 4 and showed a rise in coronavirus levels in waste water from November and into January at a higher rate than the rest of the region. As of Jan. 4, the citywide average was 3,025 copies/ML, representing a 32 percent increase over the previous 14 days.


The sharpest increase was seen in Roxbury where the eight-day moving average climbed to 6,456 copies/ML, the highest in the city, with Allston/Brighton behind it at 4,438 copies/ML, according to the data.

The city partnered with Biobot Analytics to test the samples, which will be gathered twice each week, the statement said. The results can be viewed on the city’s website at

Nick Stoico can be reached at Follow him @NickStoico.