This U.S. Geological Survey (USGS) Data Release provides spatial water-quality data collected from the St. Lucie and Caloosahatchee Rivers in October 2017, Lake Okeechobee and the Caloosahatchee River in July 2018 and the Caloosahatchee River, St. Lucie River and Lake Okeechobee in August of 2018, south Florida. Geo-referenced measurements of near surface water temperature, specific conductance, dissolved oxygen, pH, turbidity, chlorophyll fluorescence, phycocyanin fluorescence, and fluorescence of dissolved organic matter were recorded at 5 second intervals and nitrate+nitrite was recorded at 1 minute intervals during water-quality surveys in order to create high resolution water-quality maps of the study area.