Blue-green algae at Indian River County's Headwaters Lake has low but persistent toxicity

INDIAN RIVER COUNTY — The site in Headwaters Lake in northwest Indian River County where a warning about toxic blue-green algae was issued late Wednesday has had low but persistent levels of toxicity this year.

The Florida Department of Health in Indian River County issued a health alert after the toxin microcystin was detected in a blue-green algae bloom in the lake, until recently known as the Fellsmere Water Management Area, northwest of Fellsmere.

The bloom site has been sampled by the St. Johns River Water Management District six times since February. Each sample tested positive for levels of microcystin between 1 and 4 parts per billion.

The most recent sample, which prompted the warning, was taken June 24. Results posted Wednesday on the Florida Department of Environmental Protection algae bloom website showed a microcystin level of 2.38 parts per billion.

That's:

• well below the 8 parts per billion needed to be hazardous in normal recreational contact, according to the federal Environmental Protection Agency
• well below the toxicity of a bloom on the Lake Okeechobee side of the Port Mayaca Lock and Dam in western Martin County, which contained microcystin at a level of 29 parts per billion, according to a DEP post Monday
• more than twice the 1 part per billion level considered unsafe to drink by the World Health Organization

More: EPA sets hazardous level for blue-green algae toxin

Microcystin can cause nausea and vomiting if ingested, and rashes and hay fever symptoms if touched or inhaled. The toxin also has been linked to long-term, sometimes fatal, liver disease.

Some scientists believe another toxin in blue-green algae, known as BMAA, can trigger neurological diseases.

More: Unknown toxins in blue-green algae pose threat, scientist says

High levels of microcystin in a bloom near the middle of Lake Okeechobee prompted Paul Gray, a longtime Audubon biologist, to warn against eating any fish caught in the 73-square-mile lake.

More: With toxic algae in Lake O, scientist says don't eat the fish

Fish caught in a canal leading from the lake contain microcystin, but the levels are low enough to be safe to eat occasionally, according to a study by the Fort Pierce-based Ocean Research & Conservation Association.

More: Fish from C-44 Canal have low toxic levels, OK to eat occasionally

Despite the relatively low toxic level, the Headwaters Lake warning was issued by the  because the site is a fishing and camping destination, said Cheryl Dunn, environmental manager at the state agency's Indian River County office.

The warning specifically warns against eating fish from the bloom area and cooking and cleaning dishes with water from the bloom area.

"It was a community-based decision." Dunn said. "The health department left it up to the county office, and the decision (to issue the warning) was made late Wednesday in order to provide people with the best possible information."

The Health Department has not yet "looked into" the reason for toxins in that area of the lake, Dunn said.

Headwaters Lake is close to Blue Cypress Lake, where a blue-green algae bloom in June 2018 contained microcystin at a level of 4,700 parts per billion, according to ORCA.

The World Health Organization considers microcystin levels higher than 2,000 parts per billion to be "very highly hazardous" in recreational contact.

That bloom was thought to be caused by runoff from a nearby cattle ranch where sewage sludge, known as Class B biosolids, had been spread on 3,059 acres of pasture since 2013.

TCPalm investigation: Is Blue Cypress Lake phosphorus pollution from biosolids?

Dunn couldn't say whether there's a connection between blooms in Blue Cypress Lake and Headwaters Lake, but noted there is a canal connecting the two.

"The problem is that there's been sewage sludge dumped on lands throughout that area over the years," said St. Johns Riverkeeper Lisa Rinaman. "It may have been stopped recently, but it's going to take decades to undo the damage that's already been done."

Dunn said she plans to ask the water management district to test water at the site more frequently.

More: Indian River County extends biosolids moratorium

"We need to figure out with them what's going on out there," she said.

A department news release issued Wednesday evening originally indicated the bloom was in the Stick Marsh, a body of water west of Headlands Lake. Dunn said that was because most boaters access Headlands Lake via a boat ramp on the Stick Marsh.

More: Headwaters Lake boat ramp still not built

Construction on a long-awaited boat ramp on Headwaters Lake is scheduled to begin in October.