Estimated seasonal nitrogen and phosphorus loads in selected streams of the conterminous United States, 1999 - 2020

Estimated seasonal total nitrogen and total phosphorus loads during 1999 through 2020 in selected streams of the conterminous United States and water-quality and stream flow data used to generate those estimates are presented in this dataset. Loads were generated as part of the Integrated Water-Availability Assessment (IWAA) Program of the U.S. Geological Survey (www.usgs.gov/mission-areas/water-resources/science/integrated-water-ava…) using Fluxmaster (Schwarz and others, 2006, https://doi.org/10.3133/tm6B3) and Weighted Regression on Time, Discharge, and Season (WRTDS) (Hirsch and De Cicco, 2015, https://doi.org/10.1016/j.envsoft.2015.07.017). Loads were estimated initially for the Illinois River Basin (IRB) and later for the wider conterminous United States (including the IRB). Along with the water-quality data, streamflow data, and estimated nitrogen and phosphorus loads, this release also includes computer code that can be run to recreate the load estimates or modified for similar applications.