The records consist primarily of several decades of research data from the study of water quality in lakes. Prepas, who is Professor Emeritus of Natural Resource Management at Lakehead University, was also formerly employed at the University of Alberta. Much of the research was conducted on Alberta lakes, with some performed in Northwestern Ontario as well. A significant portion of the third accession consists of slides and print photographs showing research activities.

The records also include some teaching notes and course materials, as well as some correspondence and administrative material.