California State Aqueduct water en route to Southern California is pumped up through the Tehachapi Mountains (by the Edmonston Pumping Plant) to the Tehachapi Afterbay. There the aqueduct divides into East and West Branches. The West Branch water is again pumped at the Oso Pumping Plant to Quail Lake, near Highway 138 East of Gorman. From here it flows through a permanent pipeline waterway to Warne Power Plant, which is located at the inlet to Pyramid Lake. The Warne Plant was constructed by the state of California in 1983. Pyramid Lake has a surface area of and a storage capacity of with a maximum water surface elevation of above sea level. Pyramid Lake is the upper forebay for the Castaic Power Plant.