Army Corps and FIND defend nearshore dredging after residents say sand smothered reefs

The U.S. Army Corps of Engineers and the Florida Inland Navigation District (FIND) told Martin County commissioners on June 9 that a recent maintenance dredging operation in the Intracoastal Waterway was conducted under permits, with required turbidity and endangered-species monitoring, and that the material placed in the St. Lucy empoundment basin is beach-compatible and will be used by the county in planned renourishment projects.

Major Cory Bell and Ashley Fontaine of the Corps summarized the operation, saying contractor Southwind mobilized in April, dredging began May 5 and demobilization was under way after June 2. Fontaine said the work recently completed represented “approximately 70,000 cubic yards” for the Crossroads cut after the Corps modified the original scope, and that surveys and sediment testing were performed before placement. FIND’s Janet Zimmerman told commissioners M5 (a previously used upland DMMA site) was at capacity so material was retained in the local sand-sharing system by placing it in the empoundment basin.

That technical briefing followed more than an hour of public comment from boaters, conservationists and residents who presented drone footage and photos they said showed dark, silty material blown from the empoundment onto nearshore reefs and beaches and documented fish kills. “We saw fish being pulled out of the pumps and dead fish kills,” resident Scott Butler said, and Hutchinson Island advocates asked the county to halt further placement until more protections could be implemented.

County reef consultant Cheryl Miller said the county’s monitoring program uses frequent surveys and monthly drone imagery to track reef exposure and recovery. “If you put too much silt, it smothers it and it will die back,” Miller said, noting the nearshore reef system at Bathtub Beach is highly dynamic and that the county performs more intensive monitoring than typical beach projects in order to distinguish natural change from project-related impacts.

The Corps and FIND said turbidity monitoring did not register exceedances outside the permitted mixing zones and that pre- and post-construction seagrass and biological surveys will be used to evaluate any long-term impacts. Fontaine said the material placed in the empoundment basin was tested for grain size and organic content and had been authorized as compatible for beach placement by the Florida Department of Environmental Protection.

FIND’s Zimmerman acknowledged community concern and said the basin approach keeps sand in the local coastal system and avoids the cost and environmental footprint of barging material offshore and back to local beaches. She also said the district’s three-times-daily turbidity sampling results were submitted to DEP, which found them in compliance.

Commissioners asked for two follow-ups: (1) a public-facing summary of monitoring data and turbidity results, and (2) a county after-action review to determine whether additional pre-dredge sampling or placement constraints are warranted in reaches that have not been dredged for many years. Commissioner Caps urged staff to correct misinformation on social media and recommended an expedited information/response plan so residents see data and the sequence of regulatory checks used during the dredging.

Next steps: FIND and county staff said they plan to bid the St. Lucy inlet maintenance and Bathtub Beach renourishment together for January 2027 construction; the county will monitor the empoundment basin and the beaches for three years after placement.

Audience reaction and unresolved questions remain: residents continue to press for further independent review of footage that shows silty plumes and photos of dead fish, and advocates urged the county to re-evaluate the choice of placement locations when an upland DMMA such as M5 is at capacity. The Corps and FIND maintain that the project met current permit conditions and that post‑construction monitoring will show whether biological effects exceed the normal variability of this dynamic inlet system.