University of Kansas Field Station: Water temperature profiles at Frank B. Cross Reservoir (Kansas, USA) 1993-2016

These vertical profiles of water temperature data are from Frank B. Cross Reservoir, a small freshwater impoundment in northeastern Kansas (USA). Cross Reservoir, located at the University of Kansas Field Station near Lawrence (KS), has a 3-ha surface area and a maximum depth of 12 m. Temperature data were collected at discrete depths in a vertical profile using a Water Quality Checker U-10 (Horiba Instruments, Kyoto, Japan). These temperature data were collected in conjunction with ecological studies at Cross Reservoir examining deep-dwelling, vertically-migrating phytoplankton communities that form a deep chlorophyll maxima, especially during times of thermal stratification. Therefore, the most frequent sampling dates occurred in July, August, September and October during thermal stratification when vertically migrating deep algae were most common (other months were sampled less frequently through the years). Cross Reservoir has high water clarity due to its watershed vegetation and physical (protected) setting. Thermal stratification begins each year in April, and complete mixing occurs during November. The bottom of the epilimnion is typically located at 3 m in July and usually deepens to approximately 9 m by late November. The bottom of the epilimnion is defined here as the bottom of the first 1 m depth interval that exhibited a >1 C temperature decrease per meter. The water column also consistently exhibits strong chemical stratification during the summer months. Sporadic ice cover can occur during December–February.