BRADENTON – Dr. Abbey Tyrna, executive director of Suncoast Waterkeeper (SCWK), spoke to the Palma Sola Scenic Highway committee on Nov. 12 about the water quality in Palma Sola Bay.
Tyrna presented a graph showing that from 2001-11 the water quality on the north side of the Palma Sola Causeway exceeded the acceptable threshold of state water quality standards 20 times. In 2024 alone, however, in that same body of water, the threshold was exceeded 20 times.
“So we went from 20 exceedances in an 11-year period to 20 exceedances last year, so the question was what was happening here,” Tyrna said.
Palma Sola DNA source tracking results show elevated levels of horse DNA several times between April 2024 and August 2025; human DNA in July 2024 and bird DNA in April, September and October 2025.
“So, what has changed? I don’t think the number of birds has changed because what I’ve learned is that birds are actually declining,” Tyrna said.
She said the best way to figure out what is happening is through DNA testing.
“What we can see is what’s in our water samples and is detectable has been horses, humans and birds, so what can we say is causing enterococci levels in Palma Sola Bay? We can say all of them,” Tyrna said. ”If you want to know how much humans matter, how much horses matter, that’s impossible to know. There are no tests for that right now. So, we can never get there, and we should never try. And all we can do is a qualitative analysis in a robust lab. We certainly can’t do much about birds, we can do something about humans and we can do something about horses.”
Enterococci normally inhabit the intestinal tract of humans and animals. The presence of enteric bacteria can indicate fecal pollution, which can come from stormwater runoff, pet and wildlife waste products and human sewage spills. If these bacteria are present in high concentrations in recreational waters and are ingested while swimming or enter the skin through a cut or sore, they may cause illness or infections, according to the SCWK website.
“According to studies conducted by the EPA, enterococci have a greater correlation with swimming-associated gastrointestinal illness in marine and fresh waters than other bacterial indicator organisms, and are less likely to die off in saltwater. If an enterococci result exceeds 70 cells per 100 milliliters of marine water sampled, then an advisory should be issued for the sampling site,” the SCWK website states.
SCWK conducts regular monitoring of bacterial levels at 11 area recreational sites. The Benchmark EnviroAnalytical lab examines the samples for enterococci. The results are posted weekly on Suncoast Waterkeeper social media feeds.
“When one use supersedes another use, we find that to be a problem. This is why we advocate for a permit and signage system,” Tyrna said. “Suncoast Waterkeeper’s goal is to clean up the water.”
Tyrna said one of the horse ride providers at Palma Sola Bay has taken a best management practice approach to cleanup by using a boat with a paddle that brings horse manure into a net and out of the water.
“Whether or not that’s going to reduce our readings remains to be seen,” Tyrna said.
Tyrna speculated that some of the human readings could be related to sewage and possibly derelict boats.
“You don’t find a pump-out boat going to the derelict vessels so it’s logical,” she said.
