Seven Oaks Dam

The dam site is on the Santa Ana River at a narrowing of upper Santa Ana Canyon, about 1 mile upstream of the canyon mouth just north of Greenspot Road.
32330 Santa Ana Canyon Road, Highland CA.

Seven Oaks Dam Project: The Santa Ana River Mainstem Project includes the Seven Oaks Dam as a major feature. Seven Oaks Dam accounts for $450 million of the total $1.7 billion project cost. The structure is a 550 feet high earth and rock fill dam with a crest length of 2,980 feet. In early 1990, a contract was issued for testing and abutment stripping. Actual dam construction began in 1993. Completion of embankment and outlet contracts were in 2000. Care was taken during construction of the dam to insure the continuous function of the local water purveyors on the Santa Ana River. Incidental water conservation and control is a valley wide benefit as well as the purchase of 787 acres of Upland habitat, 760 acres of habitat for the Woolly-Star, San Bernardino Kangaroo Rat and the Slender-horned Spineflower—all protected species.

Description: The construction of the Seven Oaks Dam, 35 miles upstream of the Prado Dam, is a part of the Santa Ana River Mainstem project. Besides Seven Oaks Dam, this $1.7 billion project involves raising existing Prado Dam, channel construction along 23 miles of the Santa Ana River downstream of Prado Dam and channel construction on several tributary streams. The project will provide annual benefits of about $140 million to 160 square miles of urban development, mostly in Orange County, although many benefits accrue to the counties of Riverside and San Bernardino. The Santa Ana River Mainstem Project provides the necessary flood protection for over two million people and hundreds of square miles of developed lands within Orange, Riverside and San Bernardino Counties. The Corps of Engineers has estimated damages of approximately $15 billion could occur in the three counties without the protections of this project.

Seven Oaks Dam Tours: For information regarding tours of the Seven Oaks Dam please call 909-387-8128.

Seven Oaks Dam Project Data

Drainage Area
177 sq. mi.

Dam
Crest Elevation
2610 ft.
Maximum height above streambed
550 ft.
Crest Length
2980 ft.
Freeboard
6.9 ft.

Spillway
Crest Elevation
2580 ft.
Crest Length
500 ft.
Elevation of max. water surface
2604.4 ft.

Outlet Works (gated conduit)
Diameter of conduit
18 ft.
Diameter of penstock
11 ft.
Length of conduit
1623 ft.
Intake elevation
2265 ft.
Reservoir
Area at spillway crest
780 Ac.
Gross capacity (at spillway crest)
145,600 Acre-ft.

Storage allocation below spillway crest
Flood Control
113,600 Acre-ft.
Sedimentation (100-year storage)
32,000 Acre-ft.

Reservoir Design (general storm)
Total Volume
115,000 Acre-ft.
Peak inflow
85,000 feet/sec.
Peak outflow
7,000 feet/sec.

Probable Maximum Flood (general 1storm)
Total volume
356,000 Acre-ft.
Peak inflow
180,000 feet/sec.
Peak outflow
174,000 feet/sec.