"There were nearly twice as many beach closings and advisories last year than there were in 1999," the Natural Resources Defense Council said in a new report issued today. The environmental group noted, however, that much of the jump was due to increased monitoring and better reporting. Still, 11,270 beach closings and advisories were issued in 2000, the vast majority due to high levels of bacteria in the water.

Problems were reported at ocean, bay, Great Lakes and some freshwater beaches. Popular coastal regions on the list included San Diego, Jones Beach in New York and Miami Beach and Key West in Florida

The Environmental Protection Agency cautions that not enough information is available to accurately report the extent of beach pollution throughout the country.

It its 2000 report, however, the federal agency said that 24 percent of beaches reporting pollution conditions reported at least one advisory or closing.

The most frequent pollution sources were polluted runoff and storm water, followed by sewage spills and overflows, the NRDC report said. Both result in sewage, pathogens, toxics and other waste flushing into waterways and then into beach waters.

The most common illness associated with water pollution is gastroenteritis, along with ear, eye, nose, and throat infections.

Children and the elderly are more susceptible to illness after swimming in polluted water.

Epidemiologists studying a Southern California beach recently found that people swimming near flowing storm drains were 50 percent more likely to develop symptoms of pollution-related illness.