Dataset of Observed Suspended Sediment and Particulate Organic Carbon Concentrations and Modeled Long-Term Suspended Sediment and Particulate Organic Carbon Yields (1994-2017) from the Reynolds Creek Experimental Watershed and Critical Zone Observatory in Southwestern Idaho, USA

Long-term datasets of suspended sediment (SS) and particulate organic carbon (POC) are valuable to understand the role the fluvial export plays in the landscape responses to changing climate and disturbance regimes such as fire. Here we report a dataset that includes raw SS and POC concentrations and estimated long-term (\u3e 23 years) SS and POC yields from 4 nested catchments that ranged from \u3c 1 to 54 km2 in area across the Reynolds Creek Experimental Watershed and Critical Zone Observatory (RCEW-CZO) in southwestern Idaho, USA. We also estimated SS and POC yields from a burned catchment in the first two years following fire. The RCEW-CZO is representative of many rangelands in the Intermountain West USA consisting of a mosaic of vegetation including Wyoming big sagebrush (Artemisia tridentata ssp. wyomingensis) and rabbitbrush (Chrysothamnus viscidiflorus) at lower elevations and mountain big sagebrush (Artemisia tridentata ssp. vaseyana), aspen (Populus tremuloides), bitter brush (Purshia tridentata), mountain mahogany (Cercocarpus ledifolius), Utah snowberry (Symphoricarpos oreophilus), and douglas-fir (Pseudotsuga menziesii) at higher elevation areas. Mean annual precipitation across these 4 catchments ranged from 616 to 911 mm yr-1 and mean annual temperature ranged from 7.16-4.75 degrees C. We first developed relationships between SS and POC for the five catchments from two years of data, one dry and one of the wettest water years on record. We then estimated SS yields using a composite model in loadflex that performs residual correction to improve estimates with the exception of burned catchment where we used a linear interpolation. We found strong relationships between log-transformed SS and POC (R2=0.38-0.86) that varied across catchments but did not vary across years, one dry and one of the wettest water years on record. Mean annual SS yields varied from 18-89 g SS m-2 yr-1 and POC from 0.61-11 g C m-2 yr-1 across the four unburned catchments. SS and POC yields were 611 g SS m-2 yr-1 and 35 g C m-2 yr-1, respectively, from the burned catchment in the first year following fire, and yields remained elevated in the second year, at 466 g SS m-2 yr-1 and 27.5 g C m-2 yr-1, owing to the large water year. These datasets are unique because few long-term records are available across nested catchments in rangelands in the Intermountain West US, and these datasets will aid in modeling and understanding linkages between climate, erosion, and carbon