The number of beaches closing due to the unsafe conditions for swimming and to pollution declined by 12 percent in 2007 from the previous year, a report issued by the Natural Resources Defence Council showed. The report said it recorded 22,571 closures or advisory days at the nation’s 3,516 most popular beaches last year, down from the record 25,643 in 2006.

The annual report was based on data obtained from the Environmental Protection Agency. The number of beach closings or advisories attributed to pollution was fairly stable from 2006 to 2007, with more than 10,000 each year.

The largest source of pollution continues to be contamination from storm-water runoff, the report concluded.

“Our nation’s beaches continue to suffer from serious water pollution that puts swimmers at risk,” the council said in its annual report, according to Reuters. The council noted that 2007 was the third consecutive year with more than 20,000 beaches closed because they were considered unsafe due to pollution.

26 percent of closings and advisories were due to water quality tests showing elevated bacteria levels, and 18 percent were due to sewage spills, the report said. 51 percent were precautionary because of rain likely carrying pollution to swimming areas. About 7 percent of the 2007 tests nationwide showed excessive bacteria level, according to the report.

18 beaches, in California, Hawaii, Maryland, Minnesota and New Hampshire, received five-star top ratings.