Aquatic beetles in the families Dryopidae, Dytiscidae, Elmidae, Gyrinidae, Haliplidae, Helophoridae, Hydraenidae, Hydrochidae, Hydrophilidae, Noteridae, and Scirtidae were collected from the University of Mississippi Field Station (UMFS) in north-central Mississippi during May 2014 through August 2019. Located in the headwaters of the Little Tallahatchie River, UMFS encompasses 318 ha and includes over 200 ponds, springs, wetlands, and streams. We collected from mesocosms, ponds, and streams to survey the aquatic beetles of UMFS. In total, 103,113 beetles representing 132 species in 55 genera and 11 families were collected. We provide new state records for 24 species of Dytiscidae, three of Gyrinidae, three of Haliplidae, two of Hydraenidae, one of Elmidae, one of Helophoridae, one of Hydrophilidae, and one of Noteridae, with comments on the distribution, abundance, habitats, and life history of other species. Singletons represented 9.8% (13) of species collected. These data were used to estimate the total aquatic beetle species richness at UMFS and assess the effectiveness of mesocosm sampling in assessing a site's aquatic beetle richness.