This model archive summary documents the suspended-sediment concentration (SSC) model developed to estimate 15-minute SSC at Muddy Creek above Paonia Reservoir, U.S. Geological Survey (USGS) site number 385903107210800. The methods used follow USGS guidance as referenced in relevant Office of Surface Water Technical Memorandum (TM) 2016.07 and Office of Water Quality TM 2016.10, and USGS Techniques and Methods, book 3, chap. C5 (Landers and others, 2016). A total of 438 suspended-sediment samples were collected during the calibration period. Forty-one of these samples (22 equal-width-interval [EWI] samples and 19 single-point pump samples) were used in the model calibration dataset. These 41 samples were collected over the range of observed streamflow, Sediment Corrected Backscatter (SCB), and Sediment Attenuation Coefficient (SAC) conditions. Samples used in calibration were plotted on duration curve plots for streamflow from March 2005 to November 2016 (Colorado Division of Water Resources data from 2005 to 2014, and USGS data for 2015–16), and SAC for the period of record. The plots indicate that samples were collected for the observed range of conditions at the site. Suspended-sediment concentrations at this site were computed from a calibrated regression model between SSC and SAC. Streamflow, SCB, dummy variables, and seasonality were also examined as potential variables. An ordinary least squares linear regression model was developed using the ‘stats’ and ‘smwrStats’ packages in R (R Core Team, 2018). Streamflow, SCB, SAC, dummy variable, and seasonality were examined as potential explanatory variables for estimating SSC. A square root transformed SAC was selected as the explanatory variable.