7 Oaks Dam

Prado Dam

Seven Oaks Dam is a single purpose flood control project constructed by the U.S. Army Corps of Engineers, Los Angeles District. The project is located on the Santa Ana River in the upper Santa Ana Canyon about 8 miles (13 km) northeast of the City of Redlands, in San Bernardino County, California. Authorization for the project construction is contained in the Water Resources Development Act of 1986. Construction was completed on November 15, 1999. The project is planned to operate in tandem with Prado Dam, also located on the Santa Ana River 40.3 miles (64.9 km) downstream, to provide flood protection to Orange County, California. During the early part of each flood season, runoff will be stored behind the dam in order to build a debris pool to protect the outlet works. Small releases will be made on a continual basis in order to maintain the downstream water supply. During a flood, Seven Oaks Dam will store water destined for Prado Dam for as long as the reservoir pool at Prado Dam is rising. When the flood threat at Prado Dam has passed, Seven Oaks will begin to release its stored flood water at a rate which does not exceed the downstream channel capacity. At the end of each flood season, the reservoir at Seven Oaks will be gradually drained and the Santa Ana River will flow through the project unhindered. The water control manual for Seven Oaks Dam is scheduled for completion in November, 2001

Embankment
Type Earth and Rock Fill
Embankment Volume 37,626,983 CY 28,767,893 CM
Crest Elevation 2610 feet NGVD 795.5 meters NGVD
Streambed elevation at dam centerline 2060 feet NGVD 627.9 meters NGVD
Maximum height above streambed 550 feet 167.6 meters
Crest Length 2980 feet 908.3 meters
Freeboard 5.6 feet 1.7 meters
Spillway
Type Rock Cut with Flush Concrete Crest
Crest Elevation 2580 feet NGVD 786.4 meters NGVD
Crest Length 500 feet 152.4 meters
Elevation of Maximum Water Surface 2604.4 feet NGVD 793.8 meters NGVD
Main Outletworks
Intake Tower
Elevation of Tower Deck 2302.0 feet NGVD 701.7 meters NGVD
High-level Intake Elevation 2265 feet NGVD 690.4 meters NGVD
Height of Tower 225.5 feet 68.7 meters
Diameter of Main Wet Well 36 feet 11 meters
Upstream Conduit
Flow Regime Pressure Flow
Diameter of Conduit 18 feet 5.5 meters
Length of Conduit 1009 feet 307.5 meters
Elevation of Conduit Invert at Intake 2100 feet NGVD 640.1 meters NGVD
Gate Chamber
Length 69 feet 21 meters
Number of Main Gate Passages 2
Height x Width of Main Gates 8.5 x 5 feet 2.59 x 1.52 meters
Number of Low Flow Gate Passages 1
Height x Width of Low Flow Gate 3.5 x 2 feet 1.07 x 0.61 meters
Downstream Conduit
Flow Regime Open Channel Flow
Length of Conduit 578 feet 176.2 meters
Height x Width of Conduit 9 x 18 feet 2.74 x 5.49 meters
Exit Channel
Flow Regime Open Channel Flow
Length of Channel 280 feet 85.3 meters
Height x Width of Channel 14 x 18 feet 4.27 x 5.49 meters
Elevation of End of Exit Channel 2050.3 feet NGVD 624.9 meters NGVD
Multi-level Withdrawal Structure
Elevation of top of structure 2275.4 feet NGVD 693.5 meters NGVD
Elevation of invert of wet well 2100 feet NGVD 640.1 meters NGVD
Diameter of Minimum Discharge Line 3.0 feet 0.91 meters
Minimum Discharge Fixed Cone Valve 14 inches 0.36 meters
Water Supply Fixed Cone Valve 8 inches 0.20 meters
Reservoir
Area at Spillway Crest 780 Acres 3,156,548 sm
Gross Storage at Spillway Crest 145,600 Acre-feet 179.6 MCM
Flood Control Allocation 113,600 Acre-feet 140.1 MCM
Sedimentation Allocation 32,000 Acre-feet 39.5 MCM
Reservoir Design Flood
Total Volume (4-day) 115,000 Acre-feet 141.8 MCM
Peak Inflow 85,000 cfs 2406.9 cms
Peak Outflow 7,000 cfs 198.2 cms
Recurrence Interval 350 years (based on volume)
Spillway Design Flood
Total Volume 356,000 Acre-feet 439.1 MCM
Peak Inflow 180,000 cfs 5097.0 cms
Peak Outflow 174,000 cfs 4927.1 cms
Notes:
NGVD = National Geodetic Vertical Datum of 1929.
MCM = million cubic meters
cfs = cubic feet per second
cms = cubic meters per second
sm = square meters