It is a power station that uses Helms Creek canyon on the North Fork of the Kings River for off-river water storage[1] and the pumped-storage hydroelectric method to generate electricity.

When demand is low (such as at night), water is pumped into the upper reservoir to be used as stored energy at a later time.

After the water has passed through the generating turbines, it is discharged into the lower reservoir via a 3,797 ft (1,157 m) long tail-race tunnel.

The difference in elevation between the reservoirs has an effective hydraulic head (drop of the water) of 1,625 ft (495 m).

The underground power station is near Wishon Reservoir and houses three 404 MW Francis pump turbine-generators.