Datasets of suspended sediment concentration and percent fines, sampling information, and daily streamflow data were compiled and harmonized for 16 sites to better understand sediment transport and delivery in the Lower Mississippi and Atchafalaya Rivers. The compiled data were harmonized by removing unnecessary columns, screening data for laboratory or sampling issues, creating consistent entries for character columns, and dropping irrelevant data, among other steps. Fourteen of the sites are in the Lower Mississippi-Atchafalaya River Basin with two additional sites on the Middle Mississippi and Ohio Rivers. Suspended sediment concentration (total, all size fractions) and percent fines for multiple size fractions were retrieved from the U.S. Geological Survey (USGS) National Water Information System (NWIS) database. These data were matched to related sampling information, such as sampler type and sampling method, also retrieved from NWIS. Continuous daily streamflow was compiled (or estimated where missing) for all sites and these data were from NWIS and the U.S. Army Corps of Engineers (USACE). Daily streamflow records extend as far back as possible and contain no gaps, whereas suspended sediment data and sampling information were measured and reported periodically and may contain multiyear gaps depending on the site. Note, siteIndex is used as the main sediment site identifier since sediment records from more than one USGS site are combined for at least one siteIndex. Additionally, gageIndex is used as the main streamgage identifier since streamflow records from multiple streamgages are sometimes combined for a single gageIndex and a single gageIndex may be used for more than one siteIndex. See the siteTable.csv for linkages between siteIndex, gageIndex, and USGS and USACE site/streamgage numbers.

This data release contains annual estimates of total, fine (<0.0625 millimeter [mm]), and coarse (≥0.0625 mm) suspended sediment concentration and load for 11 sites located on the Lower Mississippi River and Atchafalaya River through 2021. Annual and flow-normalized estimates were calculated using WRTDSplus, an extension of the Weighted Regressions on Time, Discharge, and Season (WRTDS) model which allows users to add a fourth explanatory variable to the model formulation (DeCicco and others, 2024). Input streamflow and suspended sediment data for these models were retrieved from Murphy and others (2022). Details about data processing and model specifications can be found in the companion publication to this data release (Murphy and others, 2025).

This data release contains annual estimates of total, fine (<0.0625 millimeter [mm]), and coarse (≥0.0625 mm) suspended sediment concentration and load for 11 sites located on the Lower Mississippi River and Atchafalaya River through 2021. Annual and flow-normalized estimates were calculated using WRTDSplus, an extension of the Weighted Regressions on Time, Discharge, and Season (WRTDS) model which allows users to add a fourth explanatory variable to the model formulation (DeCicco and others, 2024). Input streamflow and suspended sediment data for these models were retrieved from Murphy and others (2022). Details about data processing and model specifications can be found in the companion publication to this data release (Murphy and others, 2025).

The primary data sets consist of loads (with upper 95-percent prediction interval, and lower 95-percent prediction interval) of suspended sediment, total nitrogen, and total phosphorus calculated from instantaneous concentrations estimated from regression models from June 23, 2015 to February 6 2019. The secondary dataset consist of daily loads calculated from the cumulative total of instantaneous loads for each day in the primary dataset.

The primary data sets consist of loads (with upper 95-percent prediction interval, and lower 95-percent prediction interval) of suspended sediment, total nitrogen, and total phosphorus calculated from instantaneous concentrations estimated from regression models from June 23, 2015 to February 6 2019. The secondary dataset consist of daily loads calculated from the cumulative total of instantaneous loads for each day in the primary dataset.

This data release contains annual estimates of suspended-sediment concentration and load for the Mississippi River, St. Francisville site and the Atchafalaya River, Melville site from 1980-2015. Annual estimates and flow-normalized estimates were generated using the Weighted Regressions on Time, Season and Discharge (WRTDS) model. Input data for the model included suspended-sediment concentrations publicly available from the U.S. Geological Survey (USGS)'s National Water Information System (U.S. Geological Survey, 2016) and daily-mean streamflow estimates from the Army Corps of Engineers (2016) and USGS. These annual concentrations and loads are used to support trend analyses and provide estimates of sediment availability to the Gulf of Mexico. See companion publication for more details (Mize, S.V., Murphy, J.C., Diehl, T.H., and Demcheck, D.K., 2018, Suspended-sediment concentrations and loads in the lower Mississippi and Atchafalaya Rivers decreased by half between 1980 and 2015, Journal of Hydrology, In review). References" U.S. Army Corp of Engineers, 2016, Water levels of Rivers and Lakes data available on the World Wide Web at RiverGages.com, accessed June 10, 2016, at URL http://rivergages.mvr.usace.army.mil U.S. Geological Survey, 2016, National Water Information System—Web interface, accessed November 8, 2017, at http://dx.doi.org/10.5066/F7P55KJN.

This data release contains annual estimates of suspended-sediment concentration and load for the Mississippi River, St. Francisville site and the Atchafalaya River, Melville site from 1980-2015. Annual estimates and flow-normalized estimates were generated using the Weighted Regressions on Time, Season and Discharge (WRTDS) model. Input data for the model included suspended-sediment concentrations publicly available from the U.S. Geological Survey (USGS)'s National Water Information System (U.S. Geological Survey, 2016) and daily-mean streamflow estimates from the Army Corps of Engineers (2016) and USGS. These annual concentrations and loads are used to support trend analyses and provide estimates of sediment availability to the Gulf of Mexico. See companion publication for more details (Mize, S.V., Murphy, J.C., Diehl, T.H., and Demcheck, D.K., 2018, Suspended-sediment concentrations and loads in the lower Mississippi and Atchafalaya Rivers decreased by half between 1980 and 2015, Journal of Hydrology, In review). References" U.S. Army Corp of Engineers, 2016, Water levels of Rivers and Lakes data available on the World Wide Web at RiverGages.com, accessed June 10, 2016, at URL http://rivergages.mvr.usace.army.mil U.S. Geological Survey, 2016, National Water Information System—Web interface, accessed November 8, 2017, at http://dx.doi.org/10.5066/F7P55KJN.

This data release consists of daily mean streamflow, daily mean suspended sediment concentration (SSC), and daily mean suspended sediment load (SSL) data for selected U.S. Geological Survey (USGS) streamgage sites within the Fountain Creek watershed, separated by water year. Each file also includes USGS approval levels and any associated qualifiers that were applied to the values. The daily mean SSC and daily mean SSL were calculated using the program, Graphical Constituent Loading Analysis System (GCLAS), and are publicly available in the USGS National Water Information System (NWIS) database. The datasets also are presented as monthly total streamflow and monthly total SSL for selected USGS streamgage sites within the Fountain Creek watershed. Seasonal totals of streamflow and SSL, ratio of SSL to streamflow, yields, and suspended sediment flux are also presented. Additionally, for each seasonal period from 1998 to 2024, there is a site comparison text file documenting net difference of streamflow and SSL between sites. This data release is intended to be updated annually as new data are collected and available. The final datasets include continuous turbidity data, which are presented from 2018 to 2024 for sites 07106500 and 07103700 that were previously unpublished and used exclusively to aid in the estimation of concentration curves within GCLAS. For water year 2024, the continuous turbidity data are included in the dataset and are not publicly available in the NWIS database but were processed generally following techniques and methods for continuous water-quality monitors. Although the previous version is available from the author, all the records in previous versions can be found in version 2.0. First posted - April 26, 2024 Revised - June, 2025 (Version 2.0)

This data release consists of daily mean streamflow, daily mean suspended sediment concentration (SSC), and daily mean suspended sediment load (SSL) data for selected U.S. Geological Survey (USGS) streamgage sites within the Fountain Creek watershed, separated by water year. Each file also includes USGS approval levels and any associated qualifiers that were applied to the values. The daily mean SSC and daily mean SSL were calculated using the program, Graphical Constituent Loading Analysis System (GCLAS), and are publicly available in the USGS National Water Information System (NWIS) database. The datasets also are presented as monthly total streamflow and monthly total SSL for selected USGS streamgage sites within the Fountain Creek watershed. Seasonal totals of streamflow and SSL, ratio of SSL to streamflow, yields, and suspended sediment flux are also presented. Additionally, for each seasonal period from 1998 to 2024, there is a site comparison text file documenting net difference of streamflow and SSL between sites. This data release is intended to be updated annually as new data are collected and available. The final datasets include continuous turbidity data, which are presented from 2018 to 2024 for sites 07106500 and 07103700 that were previously unpublished and used exclusively to aid in the estimation of concentration curves within GCLAS. For water year 2024, the continuous turbidity data are included in the dataset and are not publicly available in the NWIS database but were processed generally following techniques and methods for continuous water-quality monitors. Although the previous version is available from the author, all the records in previous versions can be found in version 2.0. First posted - April 26, 2024 Revised - June, 2025 (Version 2.0)

This model archive summary (MAS) and associated model calibration data describes a surrogate model used to compute suspended sediment concentrations at USGS streamgage 11516530 for water years 2019-2023. The methods used follow USGS guidance as referenced in Office of Surface Water (OSW)/Office of Water Quality (OWQ) technical memoranda 2016.07 (https://water.usgs.gov/osw/pubs/memo.summaries.html) and USGS techniques and methods, book 3-chapter C4 (doi.org/10.3133/tm3C4).