Yorba
Yorba is an earth dam located in Orange County, California, built in 1907. It carries a High hazard potential classification and has a satisfactory condition assessment.
About Yorba
The primary purpose of Yorba is flood risk reduction. The dam is designed to control downstream flooding by temporarily storing excess water during storms and releasing it at a controlled rate. The dam is owned by County Of Orange (local government). It impounds the Tr Santa Ana River near Atwood.
The dam stands 45 feet tall and stretches 920 feet across, creates a reservoir covering 87 acres, has a maximum storage capacity of 1,200 acre-feet, and collects water from a drainage area of 1 square miles. Completed in 1907, the structure is over a century old.
This dam carries a high hazard potential classification, which means that a failure or uncontrolled release of water would likely cause loss of human life. This classification reflects the consequences of failure, not the likelihood — it indicates that people live or work in the area downstream. Its condition is rated satisfactory, indicating no existing or potential dam safety deficiencies are recognized. An emergency action plan is in place for this dam. The most recent inspection on record was 09/17/2025.
At 45 feet, this dam is taller than 91% of dams nationwide.
Living Downstream
If you live or work downstream of this dam, consider taking these steps: learn your local evacuation routes, check whether your county emergency management office has a dam failure inundation map, and sign up for local emergency alerts. The California dam safety program can provide more specific information about emergency planning for this structure.
Search for dams near your address to see all dams in your area with hazard classifications and safety data.
Location
| State | California |
| County | Orange |
| Nearest City | Atwood |
| River/Stream | Tr Santa Ana River |
| Coordinates | 33.87130, -117.81440 |
Physical Characteristics
| Dam Type | Earth |
| NID Height | 45 ft |
| Dam Height | 45 ft |
| Dam Length | 920 ft |
| Year Completed | 1907 (119 years old) |
Storage & Hydraulics
| NID Storage | 1,200 acre-ft |
| Max Storage | 1,200 acre-ft |
| Surface Area | 87 acres |
| Drainage Area | 1 sq mi |
Ownership & Safety
| Purpose | Flood Risk Reduction |
| Owner | County of Orange |
| Owner Type | Local Government |
| Hazard Classification | High |
| Condition Assessment | Satisfactory |
| Last Inspection | 09/17/2025 |
| Emergency Action Plan | Yes |
Identifiers
| NID ID | CA00831 |
| Federal ID | CA00831 |
| More Info | State Dam Safety Program |