SANIBEL, Fla. — There are two weir systems on the island of Sanibel that control storm water runoff but do not control storm surge waters. Fox 4 Meteorologist Andrew Shipley got a look from the city on just how the weir system works and how the city of Sanibel is planning for future storms.
“We know that our residents are concerned about the amount of water that has come on the island,” said City Manager Dana Souza.
It’s fair to say that the city of Sanibel has seen its fair share of water this year, whether it was near 70 inches of rainfall or three different storm surge events from Debbie, Helene, and Milton.
“There have been questions about city’s weir management, about whether we are proactively or properly releasing water,” said Souza.
Souza addressed those concerns on Friday.
“We get the good forecasts from your station, and we watch the National Weather Service very closely so we can anticipate the rainfall we have and can increase the capacity,” said Souza.
Increasing capacity can also be a balancing act as well.
“It is certainly a unique way, a unique storm water management system that we have to balance the flood protection it provides and our goals as a sanctuary island,” said Holly Milbrandt, Natural Resource Director.
One of those goals for Milbrandt includes making sure the wetlands have enough water as well.
“The benefits of having water in this interior wetland system in terms of fire protection, again have water for wildlife, and to keep saltwater from intruding into our freshwater areas through movement of groundwater,” said Milbrandt.
As we move into the future, one things the city will have to combat is sea level rise. According to Sanibel Captiva Conservation Foundation, sea levels have risen 8 inches around the island since 1965.
“When you look at that as a whole, you might not think that is a lot,” said James Evans, CEO of SCCF. “But when you look at it from a storm water management perspective, you have all that sea water that is higher than it was several decades ago. It’s holding back on that storm water.”
That means it can take even longer for the island drain, especially given the average elevation is about four and half feet.
City Engineer Oisin Dolley describes, the weirs work by using the tides, also plays a factor.
“As sea levels rise over time, the tides are going to be generally higher, which is going to restrict and shorten the amount of time that we can open the gates,” said Dolley.
And as for storm surge, these weir systems aren’t meant to drain that kind of water.
“While we did lower levels as much as could before those storm surge events, it didn’t really matter much,” said Dolley. “Once the surge inundated this system at the severity that it did, it filled up the entire basin our system in a matter of minutes.”
But that doesn’t mean the city isn’t working to get better at getting water off the island and become more sustainable.
“In the next year there will be a lot of public meetings and a lot of discussions about how do we make Sanibel more resilient for the next 50 years and what projects do we need to undertake to accomplish that,” said Souza.
