This U.S. Geological Survey (USGS) Data Release provides phytoplankton data from Upper Klamath River, OR from 8/4/2016 - 9/10/2020 at USGS Station 11509370, Upper Klamath River abv. Keno Dam at Keno, OR. Phytoplankton data are reported to the lowest possible taxonomic level and biovolume, biomass, and density are reported.