The St. Johns River was choked by water hyacinths. After their introduction as an ornamental plant, they spread to completely cover some parts of the St. Johns and the creek systems. This caused severe problems for loggers floating timber downstream, and for steamboat traffic. Even the canal at Santa Fe was chock full.
The State tried all sorts of methods to eradicate them. One of the most benign was using floating combines to pile them up and send them downstream. Perhaps the most ecologically damaging, but effective, was spraying arsenic.
Shown here is the steamboat Everglades trying to make its way through the hyacinths on the St. Johns.
Hyacinths in Bloom, Green Cove Springs, 1931