Improving Water Quality In-stream: SALT team

We can improve water quality in-stream by slowing the velocity of stormwater, and allowing sediment, nitrogen, and phosphorus to settle out before the runoff is released to join the waters of the Mississippi Sound. The multi-disciplinary SALT team selected a site in Bay St Louis as a pilot project for the Beach Outfalls Challenge to demonstrate our approach.

At the In-Stream area, the existing channel is maintained for high-flow conditions, but additional capacity is created by deepening the original channel to slow the water runoff and delay its release. With the Land Trust as a partner, we can expand the greenway, excavating soil from land adjacent to the channel to create moist meadows and freshwater bogs with a dense carpet of native plants. These wetland plants capture contaminants, using the nitrogen and phosphorus from the runoff to cycle these nutrients back into the micro-bayou. A boardwalk provides public access and viewing of the improved waterway.

The Parque de Litoral in Mayaguez, Puerto Rico faced these same challenges.  Designed by team members Local Office Landscape, the waterfront site started out as a desolate strip on the Caribbean coastline with seven failing stormwater outfalls that exited directly to the beach, causing extensive damage to a nearby coral reef.  The project has survived seven hurricane seasons, showing measurable water quality improvements.

In Bay St Louis, team leader unabridged Architecture designed the Depot Pond at the intersection of downtown and the depot district, and was a narrow ditch until it was transformed.  The pond retains stormwater, restores habitat, and provides a place for recreation.

Beauty is the key to the success of this project.  These new landscapes must be beautiful to appeal to residents who live near the beach, and attractive to the tourists who visit.  Our proposal creates a mosaic of special landscapes. We believe that the in-stream 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.