In March this year, the Metropolitan Water District of Southern California (MWD) inaugurated Diamond Valley Lake (formerly known as Eastside reservoir). The lake is impounded by three dams that represent the largest earth and rockfill reservoir project ever built in the US.

A total embankment volume of over 84M m3 of earth

and rock were used to construct the West dam, East dam and Saddle dam. Over 30M m3 of foundations were also excavated.

The reservoir impounded by the dams, about 145km east of Los Angeles, will provide the residents of southern California with an assured water supply during an extended drought, or if an earthquake disrupts normal supplies. The 800,000 acre-feet reservoir will be filled in coming years with water from the Colorado river and Northern California, and will almost double the available storage capacity of Southern California’s major reservoirs.

The pumping plant at the reservoir consists of 12 variable speed two-stage vertical turbine pumps with 137cm diameter discharge, each rated at 4.5MW and 5m3/sec. The pumps are serviced by a 60t overhead bridge crane with a 10t auxiliary monorail crane. The intake to each pump sump is protected from intrusion of large foreign objects by stainless steel trashracks.