Highly toxic algae reported in C-44 Canal as return of Lake Okeechobee discharges looms

When Lake Okeechobee discharges to the St. Lucie River resume, the water is likely to contain highly toxic algae.

A water sample taken July 5 at the St. Lucie Lock and Dam, the conduit for Lake O water to the St. Lucie, was 15 times as toxic as what the World Health Organization considers hazardous in recreational contact.

The sample contained the toxin microcystin at a level of 154.38 parts per billion, according to information posted Tuesday on the state Department of Environmental Protection algae website.

 Anything over 10 parts per billion is considered hazardous.

Microcystin can cause nausea and vomiting if ingested and rash or hay fever symptoms if touched or inhaled. Drinking water with the toxins can cause long-term liver disease.

An Ohio State University study found people living in areas with significant algae blooms containing microcystin are more likely to die from nonalcoholic liver disease than those who don't.

Some scientists think another toxin in the algae, known as BMAA, can trigger neurological diseases.

More:Algae's long-term effects needs study, hospital CEP says

The bloom "is bright green and covers the entire visible surface" of the C-44 Canal on the upstream side of the dam, according to the DEP's algae bloom website.

The St. Lucie River is on the downstream side of the dam.

Only one of the dam's seven gates was open Tuesday, draining rainfall runoff from agricultural areas in western Martin County. When Lake O discharges resume, the gates will be open for several days of the weekly "pulse" releases.

Column: Be braced for toxic tsunami when discharges resume 

A bloom on both sides of the Moore Haven Lock and Dam, which releases Lake O water to the Caloosahatchee River, contained 59 parts per billion of microcystin, according to the DEP website.

More:5 things you should know about algae

Discharges on hold

The Lake O discharges began June 1 but were suspended July 1 by the Army Corps of Engineers.

The Corps has not decided when to resume the discharges, spokesman John Campbell said Tuesday afternoon.

It's likely the Corps will announce a decision Thursday, Campbell added, so the discharges would be back as soon as Friday.

The hiatus has helped clean out and return saltiness to the St. Lucie River estuary, said Mark Perry, executive director of Florida Oceanographic Society in Stuart.

Oysters and sea grasses, the backbone of the estuary ecosystem, need salty water to survive.

Salinity levels were just about zero when the discharges began June 1 but increased about July 4, soon after the discharges were suspended.

At noon Tuesday, salinity in the estuary near downtown Stuart was about 7 parts per thousand, high enough to keep oysters alive but not high enough for them to thrive.

"That's not horrible," said Vincent Encomio, research director at Florida Oceanographic. "But oysters aren't really safe until the salinity is at 10 parts per thousand or higher."

Keeping the discharges away for a few more days would be particularly beneficial, Perry said, because a new moon Thursday will bring stronger tides.

"We're looking at a good exchange of water coming through," he said.

Since discharges began June 1, more than 25 billion gallons of Lake O water has been dumped into the St. Lucie River. Another 54 billion gallons of rainfall runoff from western Martin County has poured through St. Lucie Lock and Dam.

Much more water has entered the river's estuary via the C-23 and C-24 canals and the north and south forks of the river.

Rainy May

A historically rainy May caused Lake O to rise quickly, which prompted the Corps to begin discharges rather than risk a breach in the Herbert Hoover Dike around the lake.

Small algae blooms started popping up in the St. Lucie four days later.

The Corps suspended discharges as blooms in the St. Lucie and Caloosahatchee estuaries expanded, originally planning for the water to start flowing again Monday. But the agency postponed the restart "to conduct a full assessment of system conditions," Col. Jason Kirk, Corps commander for Florida, said in the news release.

U.S. Rep. Brian Mast and U.S. Sens. Bill Nelson and Marco Rubio had asked the Corps to stop the discharges. Rubio sent a letter Sunday asking President Donald Trump to "use your authority to order" the Corps to reconsider the decision to restart the discharges.

More: Read Rubio's letter to Trump

Staffer Ed Killer contributed to this report.