Location and Description
Carbon Canyon Dam is a flood risk management project located near the northern edge of Orange County, Calif. The dam is about four miles east of the city of Brea and about 12 miles north of the city of Santa Ana.
In conjunction with Brea and Fullerton dams, Carbon Canyon Dam is vital for portions of the coastal plains in Orange County, including the cities of Brea, Fullerton, Placentia and Anaheim.
The Los Angeles District began construction on Carbon Canyon Dam and Reservoir in April 1959 and completed it in May 1961, under the authority of the Flood Control Act of 1936 on the basis of the 29 July 1935 report of the Orange County Flood Control District in connection with an application for a grant under the Federal Emergency Relief Appropriation Act of 1935.
The Los Angeles District operates and maintains the dam, reservoir and outlet works and develops the flood risk management plan for Carbon Canyon Dam and Reservoir.
Dam Safety Issues
The primary objective of the Corps’ Dam Safety Program is to maintain public safety by making sure dams owned and operated by the Corps are safe, and the risks to the public are minimized. An integral part of the program is the risk-informed screening process. Dams are classified based upon confirmed or unconfirmed dam safety issues, the combination of life or economic consequences should failure occur and the probability of failure. This process enables us to prioritize dam safety actions to correct deficiencies, which include interim risk reduction measures to be undertaken while further investigations are conducted and remedial actions are implemented.
Carbon Canyon Dam received a Dam Safety Action Class II, or DSAC II, rating in September 2009 based on a Screening Portfolio Risk Analysis, or SPRA, completed in March 2009. A DSAC II rating is given to dams where failure could begin during normal operations or be initiated as the consequence of an event. The likelihood of failure from one of these occurrences, prior to remediation, is too high to assure public safety; or the combination of life or economic consequences with probability of failure is very high.
Carbon Canyon Dam received a DSAC II rating because of the potential for:
- Failure from seepage and piping of embankment.
- Failure from seepage and piping along outlet conduit.
As a result of Carbon Canyon Dam’s DSAC II rating, the Corps has developed a plan to implement the following Interim Risk Reduction Measures, or IRRMs:
- Inspection and monitoring
- Flood mapping
- Update Emergency Action Plan
- Coordination with local interests/tabletop emergency exercise
- Instrumentation evaluation/monitoring
- Flood fighting
- The Corps will conduct an Issue Evaluation Study (IES), based on the national priority list and availability of future funding and staffing, to be completed approximately one year after initiation, in order to reevaluate the Carbon Canyon Dam DSAC Rating.
- If modifications are needed to address potential failure modes at the dam, the Corps will begin a Dam Safety Modification Study (DSMS) to be completed approximately 36 months after initiation.
Public Safety is Number One Priority
Public safety is our number one priority. While we cannot completely eliminate risk, we can reduce it. Our screening and classification of Carbon Canyon Dam does not mean that failure is taking place. It means we have identified dam safety issues that don’t meet industry standards and the risk to public safety is unacceptable. Routine inspections and operation of the dam will continue, and an emergency action plan was developed in coordination with local emergency management officials. Currently, there is no evidence to suggest an emergency situation exists or is about to occur.
The U.S. Army Corps of Engineers owns and operates 694 dams that serve a variety of purposes, including navigation, flood damage reduction, water supply, irrigation, hydropower, recreation, environmental enhancement and combinations of these purposes. As part of our responsibility in managing these dams, the Corps has a comprehensive Dam Safety Program that has public safety as its primary objective. Corps dams are routinely inspected and continually evaluated for safety in compliance with the Federal Guidelines for Dam Safety issued in 1979 and Engineering Regulation ER 1110-2-1156, Safety of Dams – Policy and Procedures.