Upper Oso
High HazardSatisfactory ConditionEmergency Action Plan: Yes
Location
| County | Orange |
| Nearest City | Mission Viejo |
| River/Stream | Oso Creek |
| Coordinates | 33.65970, -117.63200 |
Physical Characteristics
| Dam Type | Earth |
| NID Height | 142 ft |
| Dam Height | 142 ft |
| Dam Length | 800 ft |
| Year Completed | 1979 (47 years old) |
Storage & Hydraulics
| NID Storage | 3,700 acre-ft |
| Max Storage | 3,700 acre-ft |
| Surface Area | 115 acres |
| Drainage Area | 1 sq mi |
Ownership & Safety
| Purpose | Water Supply |
| Owner | Santa Margarita Water District |
| Owner Type | Public Utility |
| Hazard Classification | High |
| Condition Assessment | Satisfactory |
| Last Inspection | 04/03/2025 |
| Emergency Action Plan | Yes |