Seven Oaks Dam
Seven Oaks Dam is one of the largest earth and rock-filled dams in the world. It is as high as a fifty story building and ten football fields in length from side to side. Situated between the north and south branches of the San Andreas fault, the dam has been designed to withstand an earthquake of eight-plus on the Richter scale. Seven Oaks Dam is a zoned earth and rockfill dam with a maximum height of 550 feet above the existing streambed at the dam axis and 650 feet above the lowest foundation bedrock contact. The dam crest is 40 feet wide, 2,760 feet long, and has a minimum crest elevation of 2,610 feet NGVD.
Watershed
The Seven Oaks Dam watershed drains approximately 177 square miles, excluding the closed area of 32 square miles tributary to Baldwin Lake. The headwaters lie within the rugged San Bernardino Mountains. Elevations vary from 10,664 feet NGVD at Anderson Peak and 11,502 feet NGVD at San Gorgonio Peak to 2,060 feet NGVD at the dam site, which is approximately 1 mile upstream from the canyon mouth.
Seven Oaks Location
The Dam is located in the foothills of the San Bernardino Mountains, 2 miles north of Redlands, 4 miles North-Northeast of Mentone, and 1 mile upstream of the confluence of Mill Creek and Santa Ana River. The dam is accessible from Greenspot Road, 6 miles east on State Highway 30.
Purpose of Dam
The authorized purpose of Seven Oaks Dam is for flood control and debris storage only. Seven Oaks Dam provides flood protection to portions of San Bernardino, Riverside, and Orange Counties. Seven Oaks Dam has a capacity of 145,600 acre-feet at spillway crest elevation of 2580 feet NGVD, of which 32,000 acre-feet is allocated to 100 - year estimated sediment accumulation. Approximately 38,373,000 cubic yards of soil and rock were used for the construction of the embankment and adjoining overbuild sections.
The County owns and/or operates 4 other Dams and 31 Basins. For information or questions related to other County Dams or Basins feel free to contact our main line at (714) 955-0200.
