Diemer Ozone Contact Basin
Diemer Ozone Contact Basin is an other dam located in Orange County, California, built in 2011. It carries a High hazard potential classification and has a satisfactory condition assessment.
About Diemer Ozone Contact Basin
The primary purpose of Diemer Ozone Contact Basin is water supply. The dam stores water for municipal, industrial, or agricultural use, helping ensure a reliable supply for the surrounding area. The dam is owned by Metropolitan Water District Of Southern California (public utility). It impounds the Offstream near Yorba Linda.
The dam stands 32 feet tall and stretches 1,012 feet across, creates a reservoir covering 0 acres, and has a maximum storage capacity of 23 acre-feet. Completed in 2011, the structure is relatively new.
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 08/13/2025.
At 32 feet, this dam is taller than 76% 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 | Yorba Linda |
| River/Stream | Offstream |
| Coordinates | 33.91150, -117.82150 |
Physical Characteristics
| Dam Type | Other |
| NID Height | 32 ft |
| Dam Height | 32 ft |
| Dam Length | 1,012 ft |
| Year Completed | 2011 (15 years old) |
Storage & Hydraulics
| NID Storage | 23 acre-ft |
| Max Storage | 23 acre-ft |
| Surface Area | 0 acres |
Ownership & Safety
| Purpose | Water Supply |
| Owner | Metropolitan Water District Of Southern California |
| Owner Type | Public Utility |
| Hazard Classification | High |
| Condition Assessment | Satisfactory |
| Last Inspection | 08/13/2025 |
| Emergency Action Plan | Yes |
Identifiers
| NID ID | CA01492 |
| Federal ID | CA01492 |
| More Info | State Dam Safety Program |