Southern Mississippi River Delta, LA

Project Sheet

Location: Plaquemines Parish, Venice, LA, US

Year: 1992

Project Type(s): Marsh restoration

Project Description: The salt marsh receiving dredged material is located 106 km southeast of New Orleans, LA on the southern portion of the modern Mississippi Delta, near the town of Venice, LA. The salt marsh was degraded due to a combination of a high rate of sea level rise, subsidence, and sediment deficiencies as levees prevented regular sediment supply and flooding from the Mississippi River. The salt marsh received sediment additions as a slurry in January, 1992. The sediment addition resulted in a gradient of sediments depths across the marsh surface. This gradient was used to evaluate the effect of sediment depth on marsh response. These sediment depths were: reference (no sediment addition), trace sediment addition (< 2 cm), < 15 cm sediment addition, 15-30 cm sediment addition, and > 30 cm sediment addition. The addition of sediment to the marsh surface at intermediate depths reduced vegetation stress associated with prolonged inundation by increasing soil aeration and reducing the accumulation of toxic sulfides. After 15 years, the marsh area that received intermediate sediment depths were stable and resilient to experimental disturbances, suggesting sediment additions to degraded marshes at appropriate depths is a sustainable restoration technique