BOSTON, Mass. (AP) — A report has found high levels of fecal bacteria at hundreds of Massachusetts beaches that were reportedly unsafe for swimming in 2020.

Environment Massachusetts found that in the 556 beaches it researched, 264 were possibly unsafe for swimming at least one day of last year, and 29 beaches were unsafe 25% or more of the days they were tested. The samples were measured against the Environmental Protection Agency’s highest warning level.

Critics of the research like Save the Harbor/Save the Bay said that samples collected in one day cannot determine whether it is safe to swim or not.

“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,” said Chris Mancini, executive director of Save The Harbor/Save The Bay.

Environment Massachusetts said if multiple tests were taken in one day and if they were above the EPA’s limit, it was deemed a potentially unsafe day to swim.