County says Lake Manatee dam discharge not responsible for Braden River overflow

MANATEE COUNTY, Fla. — More than a month after Tropical Storm Debbie passed through the area, Manatee County officials are trying to educate the community about how Lake Manatee Dam works and why they say it is not responsible for the severe flooding that destroyed so many homes.

Tropical Storm Debbie dumped up to 18 inches (43 centimeters) of rainfall on parts of the county, requiring several hundred residents to be evacuated from their homes or vehicles.

Much of the community blamed county officials for how water was released from the dam during Debbie, prompting county commissioners to order an independent investigation.

“If you’ve experienced this disaster in your own home, when you’re looking for answers, you want to find answers that make sense to you,” Natural Resources Commissioner Charlie Hunsicker said Wednesday morning. “But I can say with 100 percent certainty that the Manatee River basin and the discharge from the dam did not go through the Braden River basin and create the flooding that occurred there.”

County officials have remained adamant that the dam operated as designed during Debbie. On Wednesday, members of the local media were invited to tour the dam and ask leaders about operations.

Lake Manatee supplies about two-thirds of Manatee County’s drinking water, about 12 billion gallons a year. County staff operate the dam 24 hours a day, monitoring water levels and inflow and outflow.

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“This structure was built for one purpose only. That purpose was to provide fresh water to the developing Manatee County by creating a dam across the Manatee River,” Hunsicker said.

The lake holds about six billion gallons of water, but Tropical Storm Debby brought in another 17 billion gallons. The top of the reservoir sits at 50 feet, but it was designed to maintain a water level between 38 and 42 feet.

During the rainy season, the lake level remains around 11 meters.

“We dropped the lake in front of Debbie to 36 feet. That’s very typical. That’s where we went for Irma. We went about the same way for Ian,” said Deputy Director of Public Services Katherine Gilmore. “It’s a normal level you can go to when you know it’s going to rain.”

Operators say that lowering the lake’s water level too much, especially as we enter the dry season, will endanger the district’s water resources.

“There’s always going to be a storm that goes beyond your design standard,” said Manatee County Deputy Commissioner Evan Pilachowski. “So if you have another event, a 54-inch rainfall event, yes, there’s going to be flooding. There’s no way to prevent that with the infrastructure that’s been built.”

Those living downstream blame the dam’s release, the timing and the information conveyed to those affected.

“The river was retreating on its own, but it wasn’t due to the Manatee River’s contribution,” Hunsicker said.

Maps showing water flow in each basin in the county have not been updated since the early 1980s.

Many sections of society blame the district administration for approving more and more development.

“I think the commissioners will definitely talk about this when we get to the COMP plan change, so it will definitely be something they will look into.”

“There’s always going to be a storm that goes beyond your design standard. So, if you have another event, a 54-inch rainfall event, yes, there’s going to be flooding. There’s no way to prevent that with the infrastructure that’s been built.”

During Debbie, the dam’s emergency spillway gate was opened because one of the three valves on the main spillway gate was not working and was being worked on as part of ongoing maintenance.

Maintenance is usually not carried out during rainy and hurricane seasons, but staff say this is done due to supply problems.

“When it comes to another major rainfall event, we can’t stop the rain from falling,” Pilachowski said. “We can certainly improve communication to residents about where we expect to see impacts.”