Swimming and the Rain

The Boston Harbor region is home to some of the cleanest urban beaches in the nation, with an overall water quality score of 95% for 2018, which is very good news.

During periods of dry weather, water quality on most of our public beaches from Nahant to Nantasket is great. However some of our beaches do better than others after summer rains, when contaminated storm water makes some area beaches unsafe for swimming for two tide cycles, about 24 hours.

That's why Save the Harbor/Save the Bay and our Beaches Science Advisory Committee is working closely with federal, state and local officials and the region's residents to identify and address conditions which can prevent the public from enjoying the benefits of our region's $5 billion investment in clean water.

So how should you decide when it is safe to swim on your favorite beach? 

According to Save the Harbor/Save the Bay's most recent Beach Water Quality Report Card, seven of the region's 13 public beaches (including beaches in Nahant, Revere, Winthrop, South Boston, Dorchester and Hull) scored a perfect 100% in 2018, and are safe for swimming all summer long, no matter what the weather has been.

Two of our beaches, King's Beach in Lynn and Swampscott, and Tenean Beach in Dorchester, are still frequently unsafe for swimming after even small summer storms. Though Lynn, Swampscott and Boston are each making progress identifying and correcting sources of contamination, there is still more work to do

Other area beaches, including Constitution Beach in East Boston, Malibu Beach in Dorchester, and Wollaston Beach in Quincy are still sometimes unsafe for swimming after frequent or intense summer storms.

Though the beach flagging system is useful, it is not perfect. It takes 24 hours for the results of a water quality test to be developed and posted on the beach, so a blue flag on the beach today means that the water was clean yesterday when it was tested, while a red flag today means that the water was dirty yesterday, though it may be safe for swimming today.

Here are our recommendations to help you make an informed decision on when and where to swim after a summer rain, based on our analysis of the scientific data and common sense.

• During dry weather - with no rain for the previous 24 hours - it is usually safe to swim on any of the region's 13 public beaches from Nahant to Nantasket.
• We recommend that you exercise caution and avoid swimming for 24 hours after intense summer storms with more than 1 inch of rain on all but the cleanest beaches.
• Based on our analysis of water quality data since 2013, you can almost always safely swim at Nahant Beach, Revere Beach, Winthrop Beach, M Street Beach, City Point Beach, Pleasure Bay, Carson Beach, Savin Hill Beach and Nantasket Beach.
• We recommend that you stay out of the water for 24 hours after rain at King's Beach in Lynn and Swampscott, Short Beach in Revere, Tenean Beach in Dorchester, and Wollaston Beach in Quincy.

Here are two links, to help you make an informed decision.

You can find the results of the most recent water quality tests for your beach at the Department of Public Health's website at https://ma-beaches.healthinspections.us/beaches.cfm?showsearch=1

Here's a useful link to the National Weather Service's daily climate report, which includes recent rainfall amounts at Logan Airport, though local rainfall amounts may vary. https://w2.weather.gov/climate/index.php?wfo=box

After a very rainy June, it looks like it is going to be near perfect beach weather this week. All of us at Save the Harbor/Save the Bay hope to see you on the beach!