When it comes to bacteria levels, swimming areas on Cape Canaveral and the islands are relatively clean compared to other parts of the state. Yet more than a dozen beaches and ponds in the region have water quality test failure rates of more than 10 percent.

This is the result of a review of government data from the Boston Globe.

April Wobst, restoration program manager for the Association to Preserve Cape Cod, pointed out the role stormwater runoff plays in closing ponds and beaches.

“Rains in our more developed areas that wash bacteria from pet or wildlife feces into our waters can cause these beaches to close,” Wobst said. “Some of these impacts may have less of an impact on the Cape because in some ways we are not as developed as other areas.”

However, she said water quality in waterways on the Cape and islands was still poor, partly due to stormwater runoff.

In Massachusetts, beaches and ponds must be closed to bathers when bacteria levels reach a certain threshold. The concentration of fecal bacteria and cyanobacteria is determined through water quality tests.

Closure rates for bathing areas on the Cape and the islands range from 0.3 percent to 18.6 percent.

“The impact of bacteria that causes closures can be very site-specific,” Wobst said. “For example, if you have a very beautiful natural area but it might be attractive to a lot of geese, that can be a source of bacteria from the goose droppings that can wash in.”

From geese to topography to proximity to built-up areas, there are many different reasons why a particular location may be prone to high bacteria levels. For many of these swimming holes, controlling stormwater runoff is key to reducing pollution.

“Stormwater management is a really important aspect and that’s something APCC has focused on in the restoration. It’s not just about reducing bacteria that lead to closures of beaches and clam pens, but also reducing nutrients that cause algal blooms in our coastal estuaries,” Wobst said.

Below is a list of the 10 swimming areas on the Cape and Islands with the highest failure rates. Data is based on state water quality test results from 2002 to 2023.

To check if your favorite bathing spot is open, visit the Massachusetts Beach Water Quality DashboardYou can also check which ponds have cyanobacteria warnings, APCC website.