This dataset provides the estimated cell abundance and total biovolume for whole-water picoplankton samples collected by the U.S. Geological Survey (USGS) at 25 different sites in Kansas between August of 2020 and August of 2022. The samples were analyzed by BSA Environmental Services, Inc. This data is part of a larger multi-agency project between U.S. Environmental Protection Agency, National Aeronautics and Space Administration, National Oceanic and Atmospheric Administration, and USGS called the Cyanobacteria Assessment Network (CyAN). The goal of the CyAN project is to develop a satellite-based, early warning system to detect harmful algal blooms (HABs) in freshwater systems.