Thermalito is one of two hydroelectric plants with reversible pump/turbines at the Oroville-Thermalito Complex, a 12-mile-wide engineered waterworks which extends from the Oroville dam in the east, to the Thermalito Afterbay in the west, in northern California. The Thermalito Dam has a powerhouse with four turbines that generate up to 120 megawatts when the water spills into the Thermalito Afterbay, a large shallow off-stream terminal reservoir, covering 4,300 acres. Three of the turbines in the Thermalito Dam are reversible, and pump water out of the Afterbay, raising the level through the entire system for ten miles, back to the Hyatt Plant, at the base of the Oroville Dam, which can lift water back up to the Oroville Reservoir, thus regulating water levels throughout the Oroville Thermalito Complex.