Grain size distributions (GSD) were determined in the lab for four sample types: bed material, suspended sediment, reservoir water, and stratigraphic column samples. Sediment samples were collected from the Rio Grande Delta upstream of Elephant Butte Reservoir in New Mexico during four field campaigns spanning between July 2021 and September 2022: (1) July 4-6, 2021, (2) March 20-22, 2022, (3) May 6-8, 2022, and (4) September 16-18, 2022. GSD were averaged over 5 total measurements with a Malvern Mastersizer 3000 laser diffraction grain size analysis system with a Hydro LV dispersion unit. The purpose of this analysis was to characterize the grain sizes of sediments in the Rio Grande Delta for material finer than gravel (sand, silt, and clay).

1. Bed material, mostly from the Rio Grande bed, and a few from mid-channel bars and/or just off the river mouth.2. Suspended sediment, all from the Rio Grande during active flow. Samples were collected at 2/3 of the total depth in the river water column. 3. Reservoir water, collected downstream from the mouth of the Rio Grande. "Top" in the location name means the sample was collected 0.5 m below the water surface, and "Bottom" means the sample was collected 0.5 m above the bed.4. Stratigraphic column, which were samples collected from shallow stratigrahpic pits in the deltaic floodplain, and the banks of the Rio Grande.