WOODBURY - The Nassau County Department of Health closed 18 beaches to bathing today as a precautionary measure, following heavy rainfall. Storm water runoff can elevate bacterial levels and affect bathing water quality.The following beaches are closed to bathing: - Centre Island Sound - Creek Club - Lattingtown Beach - Laurel Hollow Beach - Morgan Sound - North Hempstead Beach Park - Piping Rock Beach Club - Prybil Beach - Ransom Beach - Roosevelt Beach - Sea Cliff Village Beach - Soundside Beach - Stehli Beach - Tappen Beach - Hewlett Point Beach - Island Park Beach - Merrick Estates Civic Association - Philip Healey Beach Biltmore Beach Club in Massapequa has also been closed due to elevated bacterial levels.