Phytoplankton data for samples collected at twelve large river sites throughout the United States, June through October 2019

This U.S. Geological Survey (USGS) Data Release provides phytoplankton data for samples collected from twelve large river sites throughout the United States, from June through October 2019. All data are reported as raw calculated values and are not rounded to USGS significant figures. The dataset includes all routine and quality assurance/quality control samples collected as part of a National Water Quality Assessment Project pilot study to describe cyanobacteria and cyanotoxin occurrence in the Nation's large rivers. Phytoplankton were identified to the lowest possible taxonomic level with both abundance (reported as both natural units and cells) and biovolume reported.