The Diamond Valley Lake project is truly a "World Class" civil works project with materials drilled, blasted, crushed, loaded, hauled, placed, and compacted at an unsurpassed rate in the dam construction industry. The rock operations literally moved the mountain of rock from the south rim of the reservoir and placed it across the valley floor to form two two-mile long dams at each end of a 4-1/2-mile valley.
The dams are earth-core rock fill dams that make use of soil and rock materials, all obtained from areas located within the project boundary. Core materials were obtained from the silty and clayey sandy alluvium in the floor of the reservoir. Rockfill came from the bedrock near the lake's South Rim. The West Dam and Saddle Dam rockfill shells are comprised of quartzite and phyllite obtained near the western end of the reservoir, while the East Dam rockfill shells are gneiss obtained near the eastern end of the reservoir. Filter and drain materials for all three dams were obtained by crushing and processing quartzite from the western end of the reservoir.
The shovels, loaders and trucks used on the project were the largest available in the industry and established a new standard for earth and rock movement. The two rock processing plants set up for the project provided combined production exceeding the capability of any single commercial processing operation in California.