The Hydro Operating and Maintenance Expense Survey is an HGP copyrighted database covering the key performance parameters for commercial, operating, electrical-generating plants in the United States, whose primary electric power conversion source is water (both dammed water supply and pumped storage).

Issues involving Generation Capacity, Environment, Divestitures, Equipment (penstocks, turbines, gates, trash rakes, fish ladders, etc.), Relicensing, and Instrumentation are gathered and organized, providing the user with a valuable tool for both historical and current analysis by plant and industry topic.

HGP updates the database on an ongoing basis, and provides its active clients with the information and analysis held within the database.