Brea Dam, constructed, operated and maintained by the Corps of Engineers (COE), is a single purpose flood control project. The dam is located in the city of Fullerton just upstream of the fork of Brea Boulevard and Harbor Boulevard. Construction on the dam began in July 1940 and was completed in March 1942. Brea Dam, one of the units of the flood-control project for the San Gabriel River Basin and Orange County, California, was conceived under authorization of the Flood Control Act of 22 June 1936.
Brea Dam controls 22.0 square miles of drainage area of Brea Creek and its tributaries. Brea Creek generally flows southwesterly into the reservoir. Below the dam, the creek flows southward through the central business district of the city of Fullerton, where it turns westward to join Coyote Creek, a tributary of the San Gabriel river.
Brea Dam consists of : (1) an earthfilled embankment; (2) a reinforced concrete outlet works; (3) an ungated outlet; (4) a detached spillway; (5) saddle dike; and (6) reservoir.
The stand-by gate setting for the dam is currently 2 gates open at 3.5 feet. The regulation schedule at the dam during flood events is based on a combination of precipitation at the Brea Dam station during the preceding 30-minute period and current water surface elevation. Additionally, the downstream channel capacity must be monitored, and if need be, modify releases from the published schedule to prevent overtopping of the downstream channel.
The channel capacity immediately downstream of the dam is 2,000 cfs as provided by a rectangular reinforced concrete channel. For next three miles, the capacity increases to a 2,200 cfs to 3,000 cfs capacity rectangular reinforced concrete channel. In the next 2 miles of channel, the capacity expands to 11,000 cfs. For last mile, just upstream of the confluence with Coyote Creek, the capacity ranges from 3,500 cfs to 4,000 cfs.
The current water control manual for Brea Dam was approved in May 1990.
| Embankment | ||
| Type | Earth Fill | |
| Crest Elevation | 295 feet NGVD* | 89.92 meters NGVD |
| Maximum height above streambed | 87 feet | 26.52 meters |
| Crest Length | 1,765 feet | 538 meters |
| Freeboard | 5.8 feet | 1.77 meters |
| Spillway | ||
| Type | Concrete Ogee | |
| Spillway Crest | 279 feet NGVD | 85.04 meters NGVD |
| Crest Length | 150 feet | 45.72 meters |
| Outlet Works | ||
| Uncontrolled | ||
| Number of Passages | 2 | |
| Height x Width (each) | 2.5 x 3 feet | 0.76 x 0.91 meters |
| Entrance Invert Elevation | 251 feet NGVD | 76.50 meters NGVD |
| Controlled | ||
| Number of Passages | 2 | |
| Height x Width (each) | 8 x 5 feet | 2.44 x 1.52 meters |
| Entrance Invert Elevation | 208 feet NGVD | 63.40 meters NGVD |
| Conduits | ||
| Length of Conduits | 484 feet | 147.52 meters |
| Maximum Capacity | 3,800 cfs | 108 cms |
| Reservoir | ||
| Area at Top Flood Control Pool | 162.7 acres | 658,424 sm |
| Gross Storage at Spillway Crest | 4,008.5 acre-feet | 4.94 MCM |
| Flood Control Allocation | 4,008.5 acre-feet | 4.94 MCM |
| Sedimentation Allocation | 0 acre-feet | 0 MCM |
| Spillway Design Flood | ||
| Peak Inflow (12-hours) | 37,000 cfs | 1,047.2 cms |
| Peak Outflow | 27,000 cfs | 764.2 cms |
| Maximum Water Surface Elevation | 292.2 feet | 89.06 meters |
| Historic Maximum Flood | ||
| Date | 1 March 1983 | |
| Maximum Elevation | 252.0 feet NGVD | 76.81 meters NGVD |
| Peak Inflow | 2,625 cfs | 75 cms |
| Peak Outflow | 1,440 cfs | 40 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 |
| * Top of parapet wall elevation 298.0 feet. |
View/Download Current Approved Water Control Manual
Brea Dam Flood Inundation Maps
Last Updated on February 12, 1998 by R. Kuboshige
