This U.S. Geological Survey (USGS) Data Release provides spatial water-quality data collected from John Redmond Reservoir in Coffey County, Kansas, on October 7, 2014, August 13, 2015, and April 25, 2016. All data are reported as raw measured values and are not rounded to USGS significant figures. Continuous water-quality monitors were used to measure water temperature, specific conductance, turbidity, pH, dissolved oxygen, chlorophyll, phycocyanin, and nitrate at thirty-second intervals.