PAHOKEE -- What a difference a week makes.
A water sample taken by the Florida Department of Environmental Protection on May 3 showed greatly reduced toxin levels in the water. The test found just 1.2 micrograms per liter of microcystin.
A water sample taken in the lake outside the marina did not show any detectible toxins.
A water sample taken just a week before, on April 26, showed microcystin toxin levels at 860 micrograms per liter. The World Health Organization considers levels above 1 microgram per liter unsafe for drinking water and levels above 8 micrograms per liter unsafe for human recreational contact (such as swimming.)
Since April 28, South Florida Water Management District and state contractors have been at the marina removing a massive algal bloom and cleaning the water at the marina.
Part of the process used ozone to remove the microcystin toxins. This process is approved by the Environmental Protection Agency to ensure the safety of drinking water.
On Thursday, contractors completed the final step of the cleanup, using a chemical to kill any remaining Microcystis aeruginosa in the marina water.
Microcystis aeruginosa is a species of blue-green algae (cyanobacteria) found in the Lake Okeechobee Waterway. About 25% of cyanobacteria are capable of producing toxins, but even those capable of producing toxins do not always do so. The U.S. Geological Survey has documented 28 different species of cyanobacteria in the Lake Okeechobee Waterway, which includes the Caloosahatchee River, Lake Okeechobee, the St. Lucie Canal (C-44 canal) and the St. Lucie River.
In other FDEP testing on May 3, a sample taken within the water control structure at Port Mayaca was dominant for Microcystis aeruginosa and had a microcystin toxin level of 16 micrograms per liter. A sample in that same area on April 12 contained toxins of 22 micrograms per liter. A sample taken nearby on April 19 contained microcystin toxin levels of 120 micrograms per liter.
A water sample taken May 5 at Pelican Bay has tests pending.