Beach Outfalls Solution: SALT Team

The beach is a special place, at the edge where land meets water. Here on the Mississippi Gulf Coast, we enjoy spending time at the beach, in the sand, bicycling and walking along the edge.  But human settlement has had an impact on the marine environment, threatening to destroy habitats; causing sediment, marine debris, and other invisible contaminants to enter waterways; and reducing the quality and quantity of marine life – the shrimp, crabs, oysters, and fish that we depend on. How can we design a beach landscape that improves water quality and is resistant to storms?

The multi-disciplinary SALT team selected a site in Bay St Louis as a pilot project to demonstrate our approach. This beach has had a number of beach advisories in recent years, with a negative impact on tourism – and on residents who like the beach.

The Beach solution recreates the original condition of the tidal creek deltas that formed as each watershed met the Sound. A series of sand dunes will be anchored by native groundcovers, shrubs, and trees, and dune grasses that grow 10’ per year.

The overhead canopy creates a shady spot, provides habitat for migratory birds, and lowers the temperature of the water before it enters the Sound, which might otherwise be a source of stress for juvenile finfish and shellfish.

Nearshore, a series of artificial reefs creates a small oyster habitat.  The irregular forms of the proposed reefs allow free movement of small finfish and shellfish, and the salt-marsh plants on top may create a safe media for pathogens to bond.  Gabions intercept water from the outfall and prevents it from re-suspending sediment in the water.  Pathogens such as vibrio bond to the sediment, and when fast-moving water stirs it up, the pathogens can be released, causing them to seek a new host.  The reefs are designed to provide minimal obstruction to littoral drift patterns, with a gap between the beach and the new structure so that sand will not build up against it.

Beauty is the key to the success of this project.  We hope the outfall becomes a place where families take annual photos, children explore the natural world, teenagers meet to discuss their future, and adults walk each night to maintain their health. We believe that the beach enhancements will not only improve water quality, but provide a beloved spot that encourages a deeper understanding of the web of interconnections between humans and the land and marine habitats that support us.