The Oroville–Thermalito Complex is a group of reservoirs, structures, and facilities located in and around the city of Oroville in Butte County, California. The complex serves not only as a regional water conveyance and storage system, but is the headwaters for, and therefore perhaps is the most vital part of, the California Department of Water Resources' State Water Project, as one of the largest publicly built and operated water and power development and conveyance systems.