South Slough National Estuarine Research Reserve

Project Sheet

Location: Cooks County, Charleston, OR, US

Year: 1996

Project Type(s): Habitat restoration

Project Description: Five acres in the South Slough National Estuarine Research Reserve, Oregon received dredged material to mitigate loss of elevation due to diking. Diking of the marsh excluded tidal flooding while ditches redirected freshwater off the marsh. The combination of reduced sedimentation and soil oxidation resulted in the subsidence of the soil surface in Kuntz Marsh. The addition of sediment to the 5 acre marsh occurred in 1996 by excavating the top 15 to 30 cm of existing marsh soil and vegetation; this material was stockpiled for redistribution once the marsh surface was elevated through thin layer placement. Approximately 10,000 cubic meters of dredged material was excavated from the Kunz Marsh dike and mechanically spread across the marsh to the desired marsh elevation. The stockpiled marsh soil was redistributed over the dredged material. Three marsh elevations were established: high, middle, and low intertidal marsh elevations to assess the formation of tidal channels. The mid marsh elevation vegetated quickly and developed tidal channels at a rate that also enhanced sediment accretion on the marsh suggesting marsh elevation within the tidal prism and slope of the marsh are important contributing factors to successful marsh restoration.