Weymouth Memorial Reservoir
Weymouth Memorial Reservoir is an other dam located in Los Angeles County, California, built in 1966. It carries a High hazard potential classification and has a satisfactory condition assessment.
About Weymouth Memorial Reservoir
The primary purpose of Weymouth Memorial Reservoir 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 San Dimas.
The dam stands 18 feet tall and stretches 2,400 feet across, creates a reservoir covering 8 acres, and has a maximum storage capacity of 151 acre-feet. Completed in 1966, the structure is well into its service life at over 50 years 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 02/27/2025.
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 | Los Angeles |
| Nearest City | San Dimas |
| River/Stream | Offstream |
| Coordinates | 34.10990, -117.78400 |
Physical Characteristics
| Dam Type | Other |
| NID Height | 18 ft |
| Dam Height | 18 ft |
| Dam Length | 2,400 ft |
| Year Completed | 1966 (60 years old) |
Storage & Hydraulics
| NID Storage | 151 acre-ft |
| Max Storage | 151 acre-ft |
| Surface Area | 8 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 | 02/27/2025 |
| Emergency Action Plan | Yes |
Identifiers
| NID ID | CA00222 |
| Federal ID | CA00222 |
| More Info | State Dam Safety Program |