Flowing days derived from CubeSat imagery and ground observations in Hassayampa River (HR), Arizona from October 2018 to September 2021. This database includes three folders. GroundObservations: Ground observations along the HR retrieved from USGS website (https://waterdata.usgs.gov/nwis) and Flood Control District of Maricopa County using Single Sensor Data Reports tool (https://alert.fcd.maricopa.gov/showrpts_mc.html): Precip: Records of daily precipitation amount. Stream: Records of daily streamflow amount. GIS: GIS layers used in deriving flowing days. Subreach: Shapefiles of nine sub reaches along the HR. Buffer segment: Buffer zones perpendicular to HR reaches at 90 m resolution. Column ID is sorted in ascending order along the HR. Channel masks: Channel masks of HR derived from Planet data. Results BufferSegment_Flowdays.xlsx: Days with flow determined using the NIR difference threshold for water years (WY) 2019 to 2021 for each 90 m buffer areas. The relative location of each buffer areas can be found in the Buffer Segment GIS layer. ‘NaN’ suggests no data. This database supports the following paper: Wang, Z. and Vivoni, E.R. 2022. Detecting Streamflow in Dryland Rivers using CubeSats (submitted to Geophysical Research Letters).