This data release contains estimates of annual nitrogen and phosphorus loads, as well as those of other constituents, from sites in the Illinois Environmental Protection Agency (Illinois EPA) Ambient Water Quality Monitoring Network. The loads were estimated using Weighted Regressions on Time, Discharge, and Season with Kalman filtering (WRTDS-K) and existing discrete water-quality data and discharge data collected by Illinois EPA, the U.S. Geological Survey, and Illinois State Water Survey from water year 1976 to 2021 (Hirsch and others, 2015; Lee and others, 2019). All water-quality and discharge data used in this work are available from the Water Quality Portal and the National Water Information System database (U.S. Geological Survey, 2022). The data release comprises a single comma-separated values (CSV) file containing annual loads, load uncertainty, and sample counts for each ambient monitoring site. Note that the 'site' column should be loaded as a string to avoid losing the leading zeros

During water years 2016–2020, the U.S. Geological Survey, in cooperation with the Illinois Environmental Protection Agency, operated continuous monitoring stations on eight of the major rivers in Illinois to better quantify nutrient and sediment loadings from the State of Illinois to the Mississippi River. This data release presents estimates of daily nitrate, suspended sediment, and phosphorus concentrations and uncertainty over that period. The concentration estimates are based on a combination of discrete sampling data and surrogate regression (imputation). The data release comprises a single csv file containing daily timeseries of conentration and uncertainty for each monitoring station.

Phosphorus, nitrogen, and suspended-sediment loads, in 24 U.S. tributaries of the Great Lakes, were calculated using U.S. Geological Survey (USGS) data from the Great Lakes Restoration Initiative (GLRI) monitoring program for the period Oct 2010 through Sept 2020 (USGS water years 2011–2020). Total phosphorus, orthophosphate, particulate phosphorus, total nitrogen, nitrate plus nitrite, ammonium plus ammonia, and suspended-sediment loads and changes in loads were determined by applying a weighted regression approach called WRTDS (Weighted Regression on Time, Discharge, and Season). The load results represent the total mass of nitrogen, phosphorus, and suspended sediment exported downstream at each tributary site. Daily loads were estimated using the WRTDS method with Kalman filtering. To determine the change in loads between the first and last water year in record, the annual load results were flow-normalized to standardize among years with varying flow dynamics. Three primary data tables are provided that describe phosphorus, nitrogen, and suspended-sediment conditions at 24 tributaries across the U.S. Great Lakes watershed: (1) annual results, (2) daily results, and (3) changes results. The annual table is organized by USGS water year (defined as Oct 1–Sept 30). The annual and daily tables also include time-weighted mean concentrations, mean discharge, and yield estimates, the latter being calculated by dividing loads by watershed areas. Descriptions for data tables are provided in the DataDictionary.csv file. Results are also displayed in an interactive web application (https://rconnect.usgs.gov/glritrends). This data release also contains a model archive. The “model_code.zip” file contains the R code and input data to run the models, generate the results, and display the results on a shiny application. The Readme.md file includes instructions of how to run the model and descriptions of all inputs, model arguments, and outputs. Each model (saved as an eList) contains the input data (USGS station information (i.e., site information), daily discharge, and water sample data), model parameters, estimated values, and bootstrapped results. All eLists are archived in the “model_archive” folder, which is organized by sample dataset (i.e., allsamples and midsamples) and are named with the parameter and station number (e.g., NH4_04024000.RData). The RData files used in the shiny application are archived in the “shinydata” folder.

Phosphorus, nitrogen, and suspended-sediment loads, in 24 U.S. tributaries of the Great Lakes, were calculated using U.S. Geological Survey (USGS) data from the Great Lakes Restoration Initiative (GLRI) monitoring program for the period Oct 2010 through Sept 2020 (USGS water years 2011–2020). Total phosphorus, orthophosphate, particulate phosphorus, total nitrogen, nitrate plus nitrite, ammonium plus ammonia, and suspended-sediment loads and changes in loads were determined by applying a weighted regression approach called WRTDS (Weighted Regression on Time, Discharge, and Season). The load results represent the total mass of nitrogen, phosphorus, and suspended sediment exported downstream at each tributary site. Daily loads were estimated using the WRTDS method with Kalman filtering. To determine the change in loads between the first and last water year in record, the annual load results were flow-normalized to standardize among years with varying flow dynamics. Three primary data tables are provided that describe phosphorus, nitrogen, and suspended-sediment conditions at 24 tributaries across the U.S. Great Lakes watershed: (1) annual results, (2) daily results, and (3) changes results. The annual table is organized by USGS water year (defined as Oct 1–Sept 30). The annual and daily tables also include time-weighted mean concentrations, mean discharge, and yield estimates, the latter being calculated by dividing loads by watershed areas. Descriptions for data tables are provided in the DataDictionary.csv file. Results are also displayed in an interactive web application (https://rconnect.usgs.gov/glritrends). This data release also contains a model archive. The “model_code.zip” file contains the R code and input data to run the models, generate the results, and display the results on a shiny application. The Readme.md file includes instructions of how to run the model and descriptions of all inputs, model arguments, and outputs. Each model (saved as an eList) contains the input data (USGS station information (i.e., site information), daily discharge, and water sample data), model parameters, estimated values, and bootstrapped results. All eLists are archived in the “model_archive” folder, which is organized by sample dataset (i.e., allsamples and midsamples) and are named with the parameter and station number (e.g., NH4_04024000.RData). The RData files used in the shiny application are archived in the “shinydata” folder.

Phosphorus, nitrogen, chloride, and suspended-sediment loads, in 24 U.S. tributaries of the Great Lakes, were estimated using U.S. Geological Survey (USGS) data from the Great Lakes Restoration Initiative (GLRI) monitoring program for the period Oct 2010 through Sept 2023 (USGS water years 2011-23). Specific water-quality constituents include total phosphorus, orthophosphate, particulate phosphorus, total nitrogen, nitrate plus nitrite, ammonium plus ammonia, chloride, and suspended sediment. Concentrations and loads, including actual and flow-normalized estimates, were estimated with Weighted Regression on Time, Discharge, and Season (WRTDS). Results are reported at daily and annual time steps in this data release and via an interactive web application (https://rconnect.usgs.gov/glritrends). This data release is an update of a previous version for water years 2011-20. Major changes include the addition of data from water years 2021-23 and the addition of chloride to the constituents.

Nitrogen, phosphorus, and suspended-sediment loads, and changes in loads, in major rivers across the Chesapeake Bay watershed have been calculated using monitoring data from the Chesapeake Bay River Input Monitoring (RIM) Network stations for the period 1985 through 2023. Nutrient and suspended-sediment loads and changes in loads were determined by applying a weighted regression approach called WRTDS (Weighted Regression on Time, Discharge, and Season). The load results represent the total mass of nitrogen, phosphorus, and suspended sediment that was exported from each of the RIM watersheds.

Nitrogen, phosphorus, and suspended-sediment loads, and changes in loads, in major rivers across the Chesapeake Bay watershed were calculated using monitoring data from the Chesapeake Bay River Input Monitoring (RIM) Network stations for the period 1985 through 2024. Nutrient and suspended-sediment loads and changes in loads were determined by applying a weighted regression approach called WRTDS (Weighted Regression on Time, Discharge, and Season). Load results represent the total mass of nitrogen, phosphorus, and suspended sediment that was exported from each of the RIM watersheds.

Nitrogen, phosphorus, and suspended-sediment loads, and changes in loads, in major rivers across the Chesapeake Bay watershed have been calculated using monitoring data from the Chesapeake Bay River Input Monitoring (RIM) Network stations for the period 1985 through 2022. Nutrient and suspended-sediment loads and changes in loads were determined by applying a weighted regression approach called WRTDS (Weighted Regression on Time, Discharge, and Season). The load results represent the total mass of nitrogen, phosphorus, and suspended sediment that was exported from each of the RIM watersheds.

Nitrogen, phosphorus, and suspended-sediment loads, and changes in loads, in major rivers across the Chesapeake Bay watershed have been calculated using monitoring data from the Chesapeake Bay River Input Monitoring (RIM) Network stations for the period 1985 through 2022. Nutrient and suspended-sediment loads and changes in loads were determined by applying a weighted regression approach called WRTDS (Weighted Regression on Time, Discharge, and Season). The load results represent the total mass of nitrogen, phosphorus, and suspended sediment that was exported from each of the RIM watersheds.

Nitrogen, phosphorus, and suspended-sediment loads, and changes in loads, in major rivers across the Chesapeake Bay watershed have been calculated using monitoring data from the Chesapeake Bay River Input Monitoring (RIM) Network stations for the period 1985 through 2023. Nutrient and suspended-sediment loads and changes in loads were determined by applying a weighted regression approach called WRTDS (Weighted Regression on Time, Discharge, and Season). The load results represent the total mass of nitrogen, phosphorus, and suspended sediment that was exported from each of the RIM watersheds.