Algae in St. Lucie coming from many sources
OKEECHOBEE — Record rainfall in May and continuing heavy rains this month are causing ecological damage, according to a report given by South Florida Water Management District Water Resources Director Terrie Bates at the June 14 meeting of the SFWMD Governing Board. Algae found in the St. Lucie watershed is coming from many sources, not just Lake Okeechobee, she said.
“The perception that there is this huge channel of the algae coming from the lake isn’t correct,” she said.
She said there are other sources of algae coming into the estuary from the local watershed.
The watershed that drains into the canals and waterways that discharge though the St. Lucie Estuary received over 450 percent of normal rainfall in May, she said.
“All of the area, when you have 450 percent of normal rainfall, everything has discharged into the estuary system, every canal, every stormwater pond,” she continued. Algae is commonly present in all freshwater, and it tends to grow faster in stagnant water. The heavy rainfall in May flushed out ponds and canals into the drainage system that goes into the St. Lucie estuary.
She said there is even algae in the storm water pond at the SFWMD main office. “We’ve got blue-green algae in the storm water pond. It fills up; it discharges. It’s going to the C-51 canal,” she said.
“The lake jumped very rapidly in the course of a month. It has gone up about a foot and a quarter,” said Ms. Bates. “All of the effects around the system ecologically, the lake is feeling the same thing.”
On June 1, the U.S. Army Corps of Engineers started discharging water from Lake Okeechobee east to the St. Lucie and west to the Caloosahatchee, she continued.
“The discharge to the estuaries for the last week, about a third of the flow coming into the St. Lucie estuary were from Lake Okeechobee. We’re still having significant discharges coming from those local basins and tidal tributaries,” she said.
Even before any discharges started from Lake Okeechobee, the estuary had already been completely overloaded with freshwater, she said.
“Now the lake is contributing to continuing those low salinity levels,” she said.
On the Caloosahatchee side, about 50 percent of the freshwater flow going to the estuary is coming from Lake Okeechobee. She said the dark water plume seen on the Gulf Coast has to do with the tannin that is in the water from the Calooshatchee.
She said any time there is an algal bloom there are concerns about the potential for toxins. Not all algae produces toxins, and algae that can produce toxins does not always do so. There are many factors involved.
“You can have algae that exists throughout the system that is not toxic,” said Ms. Bates.
She said toxins have been detected in two samples but at such low levels it is barely detectable. According to the Florida Department of Environmental Protection, toxin levels have been less than 1 part per billion. The World Health Organization considers levels under 10 ppb to be safe.
She said satellite imagery shows very little algae in Lake Okeechobee. Algae is buoyant and moves with the wind, she explained. So you might see it one day and it is gone the next.
Board member Brandon Tucker, who represents St. Lucie, Martin, Palm Beach, Broward, Dade and Monroe counties, said he knows that in some areas of central Martin County that drain into the C-44 canal were inundated with 2 feet of freshwater in May.
“The issues that we are seeing right now that are being talked about with any algae signatures on the south Fork of the St. Lucie, I would assume that is from local basin rain runoff,” he said.
“This is not a Lake Okeechobee issue,” said Mr. Tucker. “This is a local basin runoff issue.
He said they need to do more with Aquifer Storage and Recovery Wells to slow local basin runoff into the St. Lucie. They also need to deal with the pollution from septic tanks in that basin to reduce the nutrient pollution to those waterways, he added.
“We need to be doing everything we can do in our local communities to deal with low-hanging fruit,” he explained.
“If the EAA (Everglades Agricultural Area) reservoir were built and working today, it would have had no effect on what we saw in the St. Lucie basin,” he said.
“We need solutions now, in the Caloosahatchee, in the St. Lucie, to deal with these big rain events.”
At the June 14 meeting, Ms. Bates shared an image that was credited to T.C. Palm. She explained the image, which was taken of the C-44 canal about 10 miles east of Lake Okeechobee shows algae flowing south into the C-44 canal from a smaller ‘dead end’ canal.