Mammoth Reservoir
High HazardSatisfactory ConditionEmergency Action Plan: Yes
Location
| County | Placer |
| Nearest City | Granite Bay |
| River/Stream | Offstream |
| Coordinates | 38.81860, -121.13900 |
Physical Characteristics
| Dam Type | Earth |
| NID Height | 23 ft |
| Dam Height | 23 ft |
| Dam Length | 2,360 ft |
| Year Completed | 1851 (175 years old) |
Storage & Hydraulics
| NID Storage | 103 acre-ft |
| Max Storage | 103 acre-ft |
| Surface Area | 11 acres |
| Drainage Area | 0 sq mi |
Ownership & Safety
| Purpose | Other |
| Owner | Placer County Water Agency |
| Owner Type | Local Government |
| Hazard Classification | High |
| Condition Assessment | Satisfactory |
| Last Inspection | 09/24/2025 |
| Emergency Action Plan | Yes |