Red tide, originating from naturally occurring ocean organisms, can be exacerbated by human activities. Although Lake Okeechobee is far from Sarasota, the release of its freshwater to manage flood risks can intensify red tide blooms along the Sarasota coast, about 100 miles away.

A study published in The Florida Scientist highlights how nitrogen-rich water from Lake Okeechobee, flowing through the Caloosahatchee River into Estero Bay and Charlotte Harbor, correlates with the duration of red tide outbreaks. 

Steve Suau, a water engineer and co-author of the study, explained, “The tons of nitrogen that you’re putting in 30 days before and 30 days after a red tide bloom starts correlates with how long the red tide bloom lasts. It’s a really strong correlation.”

Lead author Dave Tomasko, director of the Sarasota Bay Estuary Program, added, “What we’re basically saying is humans aren’t causing red tides, but we can cause them to be worse.” He advocates for reducing the water releases from Lake Okeechobee to potentially decrease the duration of red tide events.

Tomasko emphasized that addressing this issue requires controlling water flow, stating, “To fix this problem you have to go after the flows. There is not a magic wastewater treatment plant upgrade or stormwater retrofit that is going to fix this. We have to work up above the lake, in the lake, and below the lake to reduce the flows enough to get this under control.”

The high nitrogen content in the water from Lake Okeechobee and its surrounding areas comes from industrial activities, agricultural runoff, and septic systems. This nitrogen acts as a nutrient for red tide, enhancing its growth. 

The study examined five river basins, finding that the statistically significant relationship between water release and red tide duration was particularly evident in the Caloosahatchee basin, underscoring the direct influence of Lake Okeechobee’s water management on red tide occurrences.

Tomasko noted, “That’s one of the cool findings. You can explain the red tide duration almost as well just looking at water flow as looking at nutrient loads.” The study showed that 77% of the variability in red tide duration could be explained by nitrogen load variations in the first 60 days of an outbreak.

This research could guide water management strategies to assess the effectiveness of pollution reduction projects. Tomasko illustrated, “If you have a project that can do, like 20 percent, now we can basically say, ‘Well, that’ll shave a couple of weeks off the next red tide, on average.’”

While the study does not make specific recommendations, Suau expressed his personal view: “My opinion is the state buys out Big Sugar and restores the Everglades, (and) lets Lake Okeechobee flow back into the Everglades.” However, he acknowledges that opinions on solutions vary widely.

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