MARTIN COUNTY — A recent U.S. Army Corps of Engineers dredging project at the St. Lucie Inlet has drawn scrutiny from residents and environmental advocates after drone footage circulated online showing thousands of cubic yards of material being pumped from the inlet into the St. Lucie Impoundment Basin.
The project was completed June 2 and was undertaken to address shoaling in the inlet, according to Ashleigh Fountain, a project manager with the Army Corps.
"We dredge this area approximately every three years. We survey it on an approximate annual basis. Shoals can cause draft restrictions and all of our surveys may be found on Hydro," she said.
Shoals are accumulations of sand that can create shallow areas that are difficult for boaters to navigate.
Fountain said maintaining navigable waterways is important to the local economy. According to the Florida Inland Navigation District, water-related activity contributes about $1.2 billion to the area's economy.
"I think we can all say with certainty that there's a clear connection between the waterways and Martin County's economic vitality," she said.
While the need for dredging was largely understood, concerns emerged over the material removed from the inlet and how it was handled.
Mark Perry, executive director of the Florida Oceanographic Society, said testing conducted by his organization found the dredged material was not suitable for beach renourishment.
"It did not meet beach quality sand. In fact, it was very fine silt and sediments that were probably at the bottom of the intercoastal waterway whenever the dredge was in that area at that time," he said.
The Army Corps conducted its own testing and determined the material was appropriate for beach use. County officials said testing results can vary depending on where and when samples are collected.
Perry also raised concerns about the turbidity visible in drone footage of the project.
Fountain acknowledged dredging creates turbidity but said monitoring showed the project remained within federal requirements.
"Dredging innately does cause turbidity. It is the nature of dredging. Turbidity can impact some of these habitats," she said. "We want to make sure that our project is not doing that. And the number of turbidity exceedances that we had during this project outside of the mixing zone were zero."
Janet Zimmerman, executive director of the Florida Inland Navigation District, said she regularly visited the site and reviewed conditions shown in the footage.
"I was out at the site weekly to double check on what turbidity plumes were being shown in the video. I do have some of my own photos from those days. I do believe we were in compliance," she said.
Another point of contention involved fish found dead near the project area.
Perry said documentation provided to his organization showed fish mortality associated with the dredging operation.
"We also got pictures of and documentation about 128 fish dead on the beaches north of the inlet," he said.
Fountain said fish deaths can occur during dredging operations and were not unusual for a project of this type.
"Sometimes fish can go through the cutter. They can go through the pipeline and they can come out of the discharge pipe and be perfectly fine. But sometimes they are not," she said. "That is just the fact of the matter of the process of dredging. I do not think it was more than any other dredging operation."
Questions were also raised about why material was not placed at a site commonly used for similar projects.
Perry said the project should have utilized the M5 site, a Florida Inland Navigation District property near the Crossroads area.
"They should have been using M5, which is the FIND site on the southeast corner of the crossroads. And we just needed to make sure that that site could have been used. It's 15 acres," he said. "It's the site where they've used before. It's got a big high berm around it and it contains the silt and sediment and anything you're dredging out of the intercoastal waterway contains in there."
Zimmerman later told county staff that the M5 site had reached capacity and could not accommodate material from the project.
County staff said the material collected through the dredging effort is expected to be used in future beach renourishment projects in 2027, reducing costs to taxpayers.