Posted on March 6, 2025
DAUPHIN ISLAND, Ala. (WPMI) — The Dauphin Island Causeway Shoreline Restoration Project has been designed and funded to restore critical marsh habitat and to increase the resilience of the Causeway, the Island’s sole evacuation route.
The project spans 3.5 miles from Bayfront Park to Cedar Point. Over 150,000 tons of rock has been placed to create segmented breakwaters. Construction was completed in June of 2024. These breakwaters are designed to provide critical wave protection to the Causeway.
In the winter of 2025 through spring of 2025, the USACE Mobile District will fill the area behind these breakwaters with 800,000 cubic yards of dredge material from the Mobile Harbor Deepening and Widening Project.
Approximately 80 acres of marsh habitat will be created with this material further protecting the Causeway and creating essential fish habitat.
The beneficial use of dredged sediment that would otherwise be lost to offshore dumping is critical to keeping Mobile Bay’s sediment resources in our system whilst restoring marsh that has been lost to erosion.
This project is being implemented in three phases:
PHASE 1 (COMPLETED SEPTEMBER 2024)
Mobile County Commission, through grant funding, constructed segmented breakwaters along 3.5 miles of the Causeway. The northern segment spans from Bayfront Park to Jemison’s Bait Shop. The southern segment spans from Heron Bay Cutoff to Cedar Point. Temporary floatation access channels were required
for equipment access (Figure 1). Side casted material for those access channels will degrade with time.
PHASE 2 (TO COMMENCE WINTER – SPRING 2025)
The USACE Mobile District will place dredged sediments between the breakwaters and the Dauphin Island Causeway to create a marsh platform. The sediment that is being placed will come from the Choctaw turning Basin. Sediment will be transported via barge down the ship channel, and then pumped into the site through a pipeline. The pipeline will extend from the offloading area to the site. A sand berm will be constructed immediately adjacent to the breakwaters to provide additional containment and mimic the natural sand ridges observed in native marsh of Mobile Bay (Figure 2). Marsh fill will be pumped behind the sand berm. The sediment being placed at the site has been tested and permitted for open water disposal and is free of harmful contaminants. Best management practices will be implemented by the contractor to ensure that water quality in the area remains within ADEM permit requirements. Immediately after completion of Phase 2, the site will look like a dark beach (Figure 3).
PHASE 3 (TO COMMENCE IN FALL 2025)
The newly established marsh platform will then be enhanced into a more natural marsh habitat through creation of tidal creeks and planting of native marsh grasses. Gaps in the breakwaters will allow for tidal flow in and out of the restored marsh, providing a nursery habitat for species such as shrimp, crabs, and fish. The site will take approximately 3-5 years for the vegetation to fully establish (Figure 4).
