Blue-green algae is toxic, DEP says of water sample from C-44 Canal below Lake Okeechobee

Tyler Treadway | Treasure Coast Newspapers

Show Caption Hide Caption Lake Okeechobee discharges begin June 1 Environmental reporter Tyler Treadway reports on the first Lake Okeechobee discharges of 2018 from the St. Lucie Lock and Dam in Stuart.

A low level of toxins has been found in the blue-green algae at the dam where Lake Okeechobee water is being discharged toward the St. Lucie River.

The finding raises concerns about the type and toxicity of suspected blue-green algae found in several other sites farther east in the river's South Fork in Stuart.

More: Possible blue-green algae in South Fork at Stuart

The algae sample taken Monday at the Port Mayaca Lock and Dam contained less than one part per billion of microcystin, according to a Florida Department of Environmental Protection lab in Tallahassee.

Microcystin levels less than 10 parts per billion are not considered hazardous by the World Health Organization.

More: Scientists report blue-green algae pouring out Lake O toward St. Lucie River

DEP has not released test results of water samples taken Wednesday at the boat ramp on the South Fork of the St. Lucie River at Riverland Mobile Home Park in Stuart.

The Port Mayaca water sample was taken four days after the Army Corps of Engineers started discharging Lake O water toward the St. Lucie River.

Port Mayaca connects the lake to the C-44 Canal, which flows east to the St. Lucie River about 26 miles away.

Since they started June 1, the discharges have totaled about 4.2 billion gallons.

More: Keep track of Lake Okeechobee discharges

Algae blooms

Microcystin is a toxin prevalent in the algae blooms that covered the St. Lucie River estuary in 2016, which also polluted the Indian River Lagoon and — for the first time — Atlantic beaches on a Fourth of July holiday weekend.

The discovery of toxins in the algae is "very concerning ... because we're just now on the leading edge of the discharges and the blooms," said Edie Widder, founder and lead scientist at the Ocean Research & Conservation Association in Fort Pierce. "The algae blooms and the toxins are going to start building up in still waters along the river's shoreline."

Algae blooms occur naturally in freshwater lakes, including Lake Okeechobee. They don't occur naturally in the St. Lucie River estuary, which is usually too salty for algae to thrive.

The influx of rainfall runoff into the estuary from canals stretching west into farmland in Martin and St. Lucie counties, plus the Lake O discharges, have turned the normally brackish estuary into freshwater.

"It all goes back to draining the swamp that once was most of South Florida," Widder said. "Canals were built to accommodate farming, but they're killing the St. Lucie River estuary. The Lake Okeechobee discharges are only the most extreme example."

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