The dumping takes place in a state heavily dependent on tourism and the patronage of international celebrities and the wealthy who maintain homes there.

The practice dates back to the 1940s and has gone little noticed amid rampant development and haphazard coastal-protection policies. Only recently has it started to gain attention.

Intensive red tides -- blankets of potentially toxic algae -- and frequent beach closings due to unsafe bacteria levels have already diminished the allure of Florida's world-famous shoreline.

Bowing to pressure from environmental groups, the Florida Senate recently passed a bill backed by Gov. Charlie Crist that would eventually shut down six pipes that carry waste water into the Atlantic from Miami-Dade, Broward and Palm Beach counties. The state House of Representatives is expected to clear the bill later this month.

But Janet Llewellyn, head of water resource management at the Florida Department of Environmental Protection, acknowledges that it will likely take 16 more years before the pipes are totally closed, at an estimated cost of up to $3 billion.

"The whole idea of it just kind of makes me sick," said Ed Tedtmann, a scuba diver and Sierra Club activist who said he no longer swims off his home in Boynton Beach, Florida, because of what he sees as the man-made environmental disaster looming offshore.

The six so-called sewage "outfall" pipes stretch from one to 3.5 miles (1.6 to 5.6 km) offshore. The dumping occurs out of sight, at depths of about 100 feet (30 meters).

State officials have argued for years that the waste dissipates at sea and causes little or no near-shore pollution because it is quickly carried north in the Gulfstream current.

"The human health risks are low because of the dilution involved, and the outfall discharges are disinfected," said Llewellyn.

Marine scientists, however, say the minimally treated effluent is potentially harmful to humans, especially small children, the elderly and anyone with a weakened immune system. They also argue that it is hurting coastal ecosystems since it contains high levels of nitrogen, ammonia and other contaminants associated with the algae blooms that periodically suffocate coral reefs.

"The state has been reluctant to admit that these discharges are affecting the reefs," said Peter Barile, a scientist at Marine Research and Consulting of Melbourne, Florida. "We've had very, very strong evidence but, amazingly, a reluctance by the state to admit this," he said.

That is because waste-water treatment tends to be costly, Barile said, especially when it comes to upgrading plants like the aging structures connected to the Florida outfalls.

"This is one of these 800 pound gorillas in public planning and public works in South Florida," Barile said.

MUTANT FISH

David Guest, a Tallahassee-based lawyer with Earthjustice, a non-profit group dedicated to enforcing and strengthening environmental laws, said far more has to be done. "This is an edge of a bigger Florida problem and a bigger national problem," Guest said. "Pollution from sewage is contaminating waters all over, everywhere."

To be sure, waste-water sewage outfall pipes are not unique to Florida. Southern California, which also relies on them, is among areas where officials have been accused of treating the ocean like a giant toilet.

Environmental advocates have been highlighting the issue as they also urge regulators nationwide to find ways to slash the amount of raw sewage that belches out of older municipal sewer systems, often designed to overflow during heavy rainfalls.