The waterways around here(sarasotacharlote city) originate in the central part of the region and carry all the run off from the farms and ranches that then dump into Charlotte Harbor and work into the Gulf.
Tampa area has their own Phosphate problems
All those fertilizers and chems contribute to Red Tide here and up Tampa way.
Living down in Palm B the problem was the sugar cane guys runoffs going into Okeechobee thanks to the same Canal network down there.
DeSantis is working to correct that.
Just throw in some water hyacinth. It’l suck those nutrients right up. Problem solved. /s