Wetland sediment data was collected from coastal Louisiana as part of a pilot study to develop a diatom-based proxy for past wetland water chemistry and the identification of sediment deposits for tropical storms. The complete dataset includes forty-six surface sediment samples and nine sediment cores. The surface sediment samples were collected in fresh to brackish marsh throughout the southwest Louisiana Chenier Plain and are located coincident with Coastwide Reference Monitoring System (CRMS). Sediment cores were collected at Rockefeller Wildlife Refuge. The data described here include sedimentary properties, radioisotopes, x-radiographs, and diatom species counts for depth-interval samples of sediment cores.