The latest tally is the highest since NRDC began tracking the problem 15 years ago.

"Instead of closing our beaches, let's clean up the water," said Nancy Stoner, director of NRDC's Clean Water Project.

"Authorities have gotten better at finding the problems. Now they need to stop the pollution at its source by repairing and replacing leaky sewage and septic systems, and cleaning up contaminated runoff," she added.

Biggest Jumps in Bad Beach Days

States with the biggest jump in closing and advisory days from 2003 to 2004:

Hawaii went from no closing or advisory days in 2003 to 1,169 in 2004; Maine went from none in 2003 to 56 in 2004. Nationally, the number jumped 9 percent -- from 18,224 days in 2003 to 19,950 days in 2004.

"This is a nationwide problem that demands a nationwide solution," said Stoner. "We need stronger enforcement for those who aren't doing their share, and we need more federal help for local communities to control runoff and update their aging sewage systems. Just this week, Congress cut the Clean Water State Revolving Fund, the main federal support for water infrastructure. We're going backward."

Eighty-five percent of the closing and advisory days were prompted by dangerously high bacteria levels, indicating the presence of human or animal waste, the report says. The main culprits are improperly treated sewage and bacteria-contaminated stormwater runoff.

The bacteria cause a wide range of diseases, including gastroenteritis; dysentery; hepatitis; ear, nose and throat problems; and respiratory ailments. Consequences are worse for children, the elderly, pregnant women, and anyone with a weakened immune system, notes NRDC.

Economic Consequences

Polluted beachwater poses a threat not only to public health, but also to local businesses, NRDC points out. Ocean-related economic activity alone contributed more than $200 billion to the US economy in 2000. Coastal tourism and recreation are two of the fastest-growing businesses in the country, according to the US Commission on Ocean Policy.

But US "beachanomics" would be even more robust if communities were not forced to close their beaches because of pollution, the group maintains. For example, closing a Lake Michigan beach could result in losses of as much as $37,000 per day, according to a report cited in NRDC's study. p> Among the reasons for the jump in closings and advisories last year:

Improving Beachwater Quality

The NRDC report calls on Congress to fully fund the BEACH Act and the Clean Water State Revolving Fund, the principal source of federal support for water infrastructure.

It also urges the Environmental Protection Agency to tighten controls on sewer overflows and stormwater discharges; ensure that states and localities monitor water quality and notify the public when it does not meet bacterial standards; and set standards to protect the public from water-borne pathogens.

At the state and local level, NRDC recommends governments adopt rigorous monitoring and beach-closure programs, identify pollution sources, and get to work cleaning them up. In addition, authorities should issue advisories when heavy rainfall causes bacteria levels to jump, and when sewer overflows or other similar problems jeopardize beachwater safety.

Citizens also can do a number of things to improve beachwater quality, including capturing runoff from roofs and driveways; maintaining septic systems; picking up pet waste; avoiding chemical fertilizers and pesticides on lawns and gardens; and supporting legislation and funding to keep beachwater clean, fix aging sewer systems, and protect wetlands and coastal vegetation.