Florida county experiments with glass beach

Some people, however, are raising caution flags.

"There's no way that you can predict all the environmental consequences of an action like this," said Dennis Heinemann, a senior scientist with the Ocean Conservancy. "There always will be unforeseen consequences."

One example sits just off shore.

The state and Broward County are spending millions to remove some 700,000 tires that were placed off Fort Lauderdale in the 1970s to create an artificial reef. The tires came loose, scouring the ocean floor and wedging against natural reefs, killing coral.