CENTERPORT - A new study of Long Island's beaches warns that pollution from stormwater runoff and sewage plants is making swimming dangerous.

The study conducted by the National Resources Defense Council (NRDC) listed the Centerport Yacht Club Beach as the worst beach on Long Island, followed by Glen Cove's Crescent Beach, Copiague's Tanner Park, Laurel Hollow Village Beach and Sandspit Beach in Patchogue.

The NRDC says last year, there were significantly fewer beach closures due to poor water quality than in previous years because it rained less.

Still, Adrienne Esposito, of the Citizens Campaign for the Environment, says towns and municipalities need to take action.

"To improve the water quality, we really need to treat stormwater runoff, we really need to upgrade sewage treatment plants and get those discharge points out of our bays so those bay beaches can be clean," she says.

NRDC's report gave Jones Beach four out of five stars, which is considered a very good grade. NRDC Testing the Waters 2011