This data set encompasses approximately weekly to biweekly water quality samples from Bethel and Stephens Lakes in Columbia, Missouri. The samples were collected as part of the Reservoir Observer Student Scientists Program to examine year-round water quality parameters in these urban reservoirs. Samples were collected by high school students, college students, and staff of the University of Missouri Limnology Laboratrory. Six samples at Stephens Lake were collected by volunteer community scientists as part of the Lakes of Missouri Volunteer Program. Bethel Lake was sampled November 2017 through November 2019, and Stephens Lake was sampled November 2018 through November 2019. Temperature data was obtained from Onset HOBO temperature data loggers that were deployed in 0.5-m increments from the bottom of the reservoirs to within 1 m of the surface.