Estimated Nutrient and Sediment Concentrations from Eight Illinois Rivers using Discrete Samples and Continuous Monitoring Data, Water Years 2016–2024

During water years 2016–2024 (the 12-month period from October 1, for any given year, through on September 30, of the following year), the U.S. Geological Survey (USGS), in cooperation with the Illinois Environmental Protection Agency (IEPA), operated continuous monitoring stations on eight of the major rivers in Illinois to better quantify nutrient and sediment loadings from watersheds in the State of Illinois to the Mississippi River. This data release presents estimates of streamflow and daily nitrate plus nitrite, phosphorus, and suspended-sediment concentrations, and uncertainty over that period. The concentration estimates are based on a combination of discrete sampling and surrogate regression (imputation; Hodson and others, 2021). This data release comprises, 1) a comma-separated values (csv) file containing daily time series of streamflow and nitrate plus nitrite, phosphorus, and suspended-sediment concentrations and uncertainty for each monitoring station, and 2) the model archive. Monitoring station daily loads can be computed by multiplying daily streamflow estimates with daily nitrate plus nitrite, phosphorus, or suspended-sediment concentrations for daily loads of that constituent. Summing all daily loads for a monitoring station of a particular water year will provide annual loads for each monitoring station.

Reference:
Hodson, T.O., Terrio, P.J., Peake, C.S., and Fazio, D.J., 2021, Continuous monitoring and Bayesian estimation of nutrient and sediment loads from Illinois watersheds, for water years 2016–2020: U.S. Geological Survey Scientific Investigations Report 2021–5092, 40 p., https://doi.org/ 10.3133/ sir20215092.