Conserving and Restoring Critical Habitats

The Dauphin Island Causeway Shoreline Restoration Project will restore up to 80 acres of salt marsh habitat along 3.5 miles of shoreline in Mobile Bay. The purposes of the project are to restore eroded marsh habitat and provide resilience to the Causeway, the sole evacuation corridor from Dauphin Island to mainland Mobile County that is frequently overtopped during storm events. The project is funded by NFWF's Gulf Environmental Benefit Fund (GEBF) and Emergency Coastal Resilience Fund (ECRF), and is one of the largest and most significant investments in an Alabama coastal restoration project to date.
The project is being constructed in three contract phases. The Phase 1 contract was administered by Mobile County to construct segmented low-crested breakwaters to protect the restored habitat and roadway and provide containment during the marsh fill construction activities. In Phase 2, over one million cubic yards of material dredged from the Mobile Harbor Deepening and Widening Project will be beneficially used to restore habitat through an agreement between the County and the USACE Mobile District. The sandy material from the dredging area is being used to construct a sand berm along the landward side of the breakwaters. This feature will provide additional containment and will eventually become high marsh and beach ridge habitat. The material with higher fines content will be placed landward of the sand berm as marsh fill. Finally, the County will administer the Phase 3 contract to install vegetative plantings, excavate tidal creeks, and perform other habitat enhancements.
This project's success was highly dependent upon the close coordination of Mobile County, ADCNR, USACE Mobile District, and Mobile County's consultants. This presentation will discuss the coordination efforts that were made to bring this project to fruition, key design features that enabled efficient beneficial use, challenges, and will provide an update on construction.

Ecological restoration using recycled dredged materials (BU) has been active within the purview of the Mobile District since at least 2001 with the implementation of a 40-acre project on Deer Island, Mississippi. Since that time, dozens of collaborative efforts between federal, state, ports and other partners have yielded a wide range of restoration projects aimed at addressing wholesale losses of emergent habitats across coastal Mississippi, Alabama and West Florida. Collectively, much has been learned from these 20+ years of experience and the recent process of permitting the 1200-acre Upper Bay Marsh Creation (UBMC) site has been particularly informative regarding large, ecosystem scale projects. 
This range of experience shows that ecosystem restoration projects with BU have been consistently successful. However, project success and familiarity have not reduced uncertainties in the permitting process because Federal agency coordination within the permitting process does not formally factor ecosystem values as part of their decision. Finally, we have seen over time that he total acreage of emergent habitat being restored across MS and AL is only about 1/10th of the acreage lost over the same period,
The UBMC permit process has clarified challenges to increasing the scale and efficiency of restoration in response to ecosystem scale changes. This includes a heightened perspective that economic and ecosystem factors are critical to understanding the full value of restoration that becomes more efficient and ecologically effective by leveraging natural productivity and recycling material resources such as dredged material. 
If economic and ecosystem factors can be more comprehensively monetized to understand their total value, including operational factors such as dredge material management costs, carbon fluxes and direct investments of time and money, it may allow new considerations for funding, permitting, design and construction. 

A major impetus for beneficial use of dredged materials (BU) began around 2000 in the USACE Mobile District that spurred construction of a 40-acre BU project on Deer Island with the MS Department of Marine Resources (MDMR) as State sponsor. This team also began a BU Master Plan and pursued a general permit for BU projects throughout Mississippi coastal waters. The Master Plan was published in 2002 but Hurricane Katrina destroyed the main files of this BU Group (BUG). Efforts to reboot BU in Mississippi began in the Gulf of Mexico Alliance around 2007. By 2008, a new BUG had been formed which developed a State BU law, interim suitability screening for dredged materials, and began implementing habitat restoration projects using "in kind" provisions of the BU law. These projects, all built without any State construction funds, were collaboratives between MDMR and either MS Ports or the Mobile District and have been acknowledged as profound and significant. Unfortunately, permitting for this collaborative program became hampered by a Mobile District regulatory reinterpretation around 2013. The USACE Mobile District alliances have endured and become even stronger in Alabama, which is poised for a renaissance of BU with significant new funding and burgeoning political support. This has made the pursuit of broad new goals such as the USACE 70% BU target and Alabama State Port Authority and Municipal (Mobile County and Town of Dauphin Island) efforts to improve dredged material management, maximize habitat restoration and nature-based features. This new era of cooperation has already established the Dauphin Island Causeway and Deer River Shoreline Restoration Projects and will usher in future programmatic approaches to provide increasing public benefits to counter steadily growing coastal needs.

The beneficial use of dredged materials has the potential to be a sustainable resource for addressing both coastal management challenges and environmental restoration efforts. In coastal Alabama, dredged material from maintenance and navigational dredging projects is being repurposed to support a variety of restoration initiatives. These include shoreline stabilization, wetland creation, and habitat enhancement. This presentation will highlight several case studies from coastal Alabama where innovative dredged material placement techniques have been developed to achieve specific restoration outcomes.

Thin layer application of dredged materials has been used for decades for the beneficial restoration and maintenance of emergent and submerged habitats to keep sediments in coastal systems, rather than ocean dumping. In order to understand the beneficial uses and limitations of these techniques, a review of the experience with the applications of thin layer placement is necessary. Starting with the initial open water thin layer work sponsored by the U.S. Army Corps of Engineers Mobile District in the 1980's, we review the development of the concept, and especially its theoretical ecological underpinnings to keep sediment in our coastal systems, and re-visit some of the early studies which demonstrated the ecological recovery following thin-layer applications. Several studies determined the open water impacts and recovery of benthic systems of open-water thin-layer placement were temporary, on the order of 2-20 weeks maximum. We also review the potential benefits for thin layer application in restoration programs, particularly in adaptive management of marsh platform in the face of sea level rise that are now being implemented along our coastal systems.

The Lower Perdido Islands are a group of three, small undeveloped islands located near Perdido Pass in Orange Beach, Alabama. In recent decades, the valuable habitats of the Lower Perdido Islands complex have experienced sustained erosion and other ecological injuries from storms, intense boat traffic, and heavy recreational use of the islands. To support management and restoration of the islands the project team performed hydrodynamic and morphological modeling, designed preliminary restoration alternatives, and developed a Comprehensive Management Plan. The modeling, collection of bathymetric data, analysis of historic habitat surveys, and stakeholder input informed design of restoration concepts with the goal of balancing human uses with restoration and conservation. These restoration concepts will be constructed from dedicated dredging of shoals in the project area. These data were integrated into the Comprehensive Management Plan which categorized the ecology and habitats of the islands and the anthropogenic influences which negatively impact the project area, while providing conservation strategies and restoration concepts to support sustainability of the islands. Through the design process Robinson and Walker Island were selected to receive dredge material for 17.7 acres of marsh restoration and 8.8 acres of dune/upland areas. Included is 1,000 linear feet of dune for recreational use and 2,600 tons for rock revetment to protect an identified high scour area. Prior to construction Moffatt & Nichol worked with the client to transplant 0.6 acres of submerged aquatic vegetation affected by the footprint of the restoration. The project will be constructed in winter of 2025. The conservation strategies and preliminary restoration designs developed as part of this planning project may be advanced and implemented in the future to support long-term sustainability of the Lower Perdido Islands.

This presentation explores three projects within Charleston Harbor, SC focused on the conservation and restoration of critical habitat. Crab Bank, a critical migratory bird sanctuary in Charleston Harbor, SC, was being lost to long-term erosion. The project restored 32 acres of critical nesting habitat through beneficial use of dredged material from the USACE Charleston Harbor deepening project. Drum Island, a historic marsh island and wading bird rookery, had been converted to a dredge disposal site in the mid 20th century. The project restored the island, including over 22 acres of marsh habitat, hammock, and tidal creeks. South Carolina Port Authority's West Cell dredge disposal site was planned to include dike raising for expanded capacity. As part of this project, avian habitat opportunities were evaluated to include in the construction. The planning report explores the challenges and benefits of several types of bird habitats that could be implemented within the active dredge spoil site. Each case study reveals the challenges and opportunities of funding, regulatory permitting, environmental impact, design strategies, effectiveness, and successful collaboration across multiple groups.