Five local beaches ace quality test in 2020; eight others not far behind 

Save the Harbor/Save the Bay has released its annual water-quality report card for the metropolitan beaches from Nantasket to Nahant, using monitoring data from the 2020 beach season, and the results were encouraging. 

In 2020, the overall water quality safety rating for Boston Harbor’s regional beaches managed by the state Department of Conservation and Recreation was 93 percent, an improvement over the prior year, which had a score of 89 percent.

Five beaches had perfect scores of 100 in 2020, including Carson Beach, City Point and Pleasure Bay in South Boston, and Revere Beach and Winthrop Beach as well. Eight other area beaches earned ratings ranging from 85 percent to 98 percent. Water quality continues to lag at Tenean Beach in Dorchester, which scored 79 percent, and at King’s Beach in Lynn and Swampscott, which scored just 70 percent in 2020.

Weekly water quality testing at Greater Boston’s regional beaches began in late May 2020. Additional daily testing of Constitution Beach, King’s Beach, Malibu Beach, Tenean Beach, and Wollaston Beach began in early June and concluded on Labor Day weekend.

These beach safety scores are calculated as the percent of water samples that comply with the Massachusetts Department of Public Health single- sample limit for bacteria, a straightforward way to evaluate seasonal beach water quality and potential impacts on public health.

Rainfall can have a significant impact on beach water quality and can vary greatly from year to year. Changes in the summer storm intensity and frequency can often explain the variations seen; 2020 was a relatively dry year, with only a few large summer storms and relatively fewer wet weather impacts. It is also important to note that some beaches are tested daily, while others are tested weekly, so in some instances a single failed test can change the rating for that beach.

These seasonal variations are why Save the Harbor/Save the Bay is reluctant to draw conclusions from results for individual years, preferring to rely on multiyear averages.

“While we are delighted with the progress that we have made on most of the region’s public beaches, we are disappointed to report that Tenean Beach in Dorchester and King’s Beach in Lynn and Swampscott were still unsafe for swimming more than one out of every five days in 2020,” said Save the Harbor/Save the Bay’s Executive Director Chris Mancini. “We are particularly concerned about the situation at King’s Beach, where filthy, bacteria- laden discharges from Lynn and Swampscott at Stacey Brook continue to threaten public health.”

“Our kids and families deserve better. Today we are calling on the Lynn Water and Sewer Commission and the Swampscott Water and Sewer Department to work together with Save the Harbor/Save the Bay, state and federal regulators, and the community to Save King’s Beach, which is a critical recreational asset to Lynn’s kids and families. This is an environmental justice issue in a diverse, dense city where healthy green and blue spaces are at a premium,” Mancini said.

Save the Harbor/ Save the Bay is also concerned about the accuracy of the beach flagging and posting protocols, where bacteria testing triggers swimming advisories.

According to Save the Harbor’s director of strategy and communications, Bruce Berman, one problem is that postings are always a day late because beach managers must wait up to 36 hours to obtain test results.  Beach water quality may have already changed significantly during this period, so the prior day’s tests often do not reflect current conditions.

In 2019, the Department of Public Health made additional changes to the beach posting and flagging protocols, which has resulted in additional days where beaches are unnecessarily posted with swimming advisories when they are in fact safe for swimming.

“While Save the Harbor recognizes the importance of protecting public health, the current system is often inaccurate and sometimes overly restrictive,” said Berman. “Over the coming months we plan to work with consultant Kelly Coughlin, of Stony Brook Partners, and with the Department of Conservation and Recreation, the Massachusetts Water Resources Authority, MADEP, USEPA, and MADPH to develop new rainfall thresholds and protocols to improve flagging and posting accuracy.”

In the meantime, Save the Harbor/Save the Bay urges beachgoers to rely on common sense when swimming after summer storms and to use the multiyear average safety ratings to help them decide when and where it is safe to swim.