The sun-drenched beaches of southeast Florida lure tourists from all over the world. But few of them may realize that a torrent of human waste is dumped silently every day into the seemingly pristine waters offshore. Every day, three densely populated counties pump into the Atlantic Ocean a total of at least 300 million gallons of partially treated urban wastewater, too polluted even for watering lawns. The dumping takes place in a state heavily dependent on tourism and the patronage of international celebrities and the wealthy who maintain homes there.