When it comes to bacteria levels, swimming areas on the Cape and Islands are relatively clean compared to other parts of the state. Still, over a dozen of the region’s beaches and ponds have water quality test failure rates of more than 10 percent.
That’s according to a review of state data by the Boston Globe.
April Wobst, restoration program manager for the Association to Preserve Cape Cod, pointed to the role that stormwater runoff plays in pond and beach closures.
“Rainfall events in our more developed areas washing bacteria from pet or wildlife waste into our waterways can be a cause of closure of those beaches,” Wobst said. “Some of that may be less impactful on the Cape, because in some ways we are not as developed as some other areas.”
But still, she said, waterways on the Cape and Islands suffer from water quality issues, caused in part by stormwater runoff.
In Massachusetts, beaches and ponds must close to swimming if bacteria levels reach a certain threshold. Levels of fecal bacteria and cyanobacteria are determined by water quality tests.
The closure rates for swimming areas on the Cape and Islands range from 0.3 percent to 18.6 percent.
“The impact of bacteria causing closures can be very site specific,” Wobst said. “If you have a very nice natural area, but one that might be attractive to a lot of geese, for example, that can be a source of bacteria from the goose droppings that can get washed in.”
From geese to topography to proximity to developed areas, there are lots of different reasons a particular location might be prone to high bacteria levels. For many of these swimming spots, managing stormwater runoff is key to reducing pollution.
"Stormwater management is a really important piece, and this is something that APCC has been very focused on for restoration, not only for reduction of bacteria that causes beach and shellfish closures, but also nutrients which cause algal blooms in our coastal estuaries as well,” Wobst said.
Below is a list of the 10 swimming areas on the Cape and Islands that have the highest failure rates. The data is based on state water quality test results from 2002 to 2023.
To check whether your favorite swimming spot is open, check the Massachusetts beach water quality dashboard. You can also check to see which ponds have cyanobacteria advisories on the APCC website.
