My ex did environmental cleanup for the gov for decades. Down at Homestead Air Base they found toxic chemicals in one of the canals that had been there for decades. They laid a concrete blanket on top of the sediment so as not to disturb it and make the situation worse.
Many people had been fishing in that very area for years. Sick! That canal also leads right into Biscayne Bay, which leads out to the ocean. And they wonder why Florida's waters are so screwed up.