fb-pixel Skip to main content

This map shows which Mass. beaches tested positive for elevated bacteria

A woman and her daughter looked for sea shells on Wollaston Beach in Quincy.Matthew J. Lee/Matthew J. Lee/Globe staff

A new report found that hundreds of locations at Massachusetts beaches were potentially unsafe for swimming in 2020 due to their concentrations of fecal bacteria.

Environment Massachusetts found that of the 556 locations examined in Massachusetts, 264 tested beaches were potentially unsafe for swimming on at least one day in 2020, and 29 beaches were potentially unsafe on at least 25 percent of the days they were tested. The report measured the samples against the Environmental Protection Agency’s highest warning level.

But Save The Harbor/Save The Bay took issue with the report and said that a single day of water samples exceeding the EPA limit was not a good measure of whether water is safe for swimming.


“Though it makes a good headline, it is hyperbolic to suggest that swimming on 264 out of 457 beaches in Massachusetts poses a threat to human health because they may have failed one water quality test in 2020 after a summer rain,” Chris Mancini, executive director of Save The Harbor/Save The Bay said. “It is misleading to release a report which includes beaches like M Street Beach in South Boston, which has failed just one test in five years along side beaches like King’s Beach in Lynn and Swampscott or Tenean Beach in Dorchester that were unsafe for swimming more than one out of every five days in 2020.”

Environment Massachusetts noted that if multiple tests took place on one day and one of the tests exceeded the safe limit for bacteria, it was considered a potentially unsafe day. The organization also said the data shouldn’t be used to rank beaches from worst to best, since how often water is tested at each beach varies, making comparisons difficult. (Read the full methodology.)

This map shows the number of days these beaches tested as potentially unsafe. Zoom in on the map to see more:


Colin A. Young of the State House News Service contributed to this report.

Amanda Kaufman can be reached at amanda.kaufman@globe.com. Follow her on Twitter @amandakauf1.