Florida development practices:
Although the bacteria are naturally occurring, the way Floridians have “managed land for 100 years” may have created an environment where the bacteria are more likely to grow, Sarasota’s Mote Marine Laboratory staff scientist Tracy Fanara said.

Increased development means higher levels of storm water runoff dumped into the Gulf of Mexico following a storm. The rapid introduction of freshwater reduces salinity levels, turning the water into a petri dish of sorts.
Tourism people must be going nuts. Remember the Mayor in Jaws?