Beneficial use of dredged sediment as a sustainable practice for restoring coastal marsh habitat.

Coastal Louisiana (USA) continues to sustain immense land and habitat losses due to subsidence, sea-level rise, and storm events. Approximately 65 million m3 (85 million cubic yards) of sediment is dredged annually from Gulf Coast federal navigation channels to maintain safe waterway passage. The beneficial use of these sediments continues to increase, and now this sediment is recognized as a critical resource in large-scale (estimated multibillion dollar) ecosystem restoration efforts to mitigate land and habitat losses along the US Gulf Coast. However, the documentation of restoration benefits where dredged sediments are the primary resource is lacking, which limits the potential for future applications. Therefore, this study documents the progress to restore marsh habitat and the resultant benefits in West Bay, Louisiana, and investigates how the restoration practices align with principles of the US Army Corps of Engineers (USACE) Engineering with Nature® (EWN® ) and UN Sustainable Development Goals (UN SDGs). West Bay, a 4964-ha subdelta adjacent to the Mississippi River, typifies risks of coastal land loss that also threatens the integrity of the adjacent federal navigation channel. To help restore coastal marsh habitat on a large spatial and temporal scale, the USACE constructed an uncontrolled diversionary channel from the Mississippi River and with subsequent direct and strategic placement of dredged sediment. Restoration performance was assessed through remotely sensed methods using data spanning approximately 70 years. To date, placement of dredged sediment in the bay has facilitated the creation of over 800 ha of new land in the formerly open waters of West Bay. The West Bay restoration project aligns with the principles of the EWN initiative, which supports more sustainable practices to deliver economic, environmental, and social benefits through collaborative processes and meaningfully integrates 10 of the UN SDGs designed to achieve a better and more sustainable future. Integr Environ Assess Manag 2022;18:1162-1173. Published 2021. This article is a U.S. Government work and is in the public domain in the USA.

Quantifying Wildlife and Navigation Benefits of a Dredging Beneficial-Use Project in the Lower Atchafalaya River: A Demonstration of Engineering with Nature®.

The US Army Corps of Engineers (USACE) operates and maintains numerous projects in support of its various civil works missions including flood damage risk reduction, navigation, and ecosystem restoration. Originally authorized on an economic basis, these projects may produce a broad array of unaccounted for ecosystem services (ESs) that contribute to overall human, societal, and environmental well-being. Efforts are underway to capture the full array of environmental, economic, and social impacts of these projects. Methods are needed to identify relevant ESs generated by these nature-based projects and to measure their contribution to societal well-being with an emphasis placed on use of readily available data. Performance metrics were collected to capture the benefits of strategic placement of dredged material in river systems to allow formation of islands that produce a wide array of ESs. These performance metrics can be converted to ESs with market value or combined in a decision analytical approach to demonstrate the relative gain in utility. This approach is demonstrated on a riverine island created on the Atchafalaya River, Louisiana, as a result of the strategic placement of dredged material. The outcomes foster integration of ES assessment into project design and management practices and support more comprehensive project evaluation and widespread application. Integr Environ Assess Manag 2018;14:759-768. Published 2018. This article is a US Government work and is in the public domain in the USA.