Puddingstone
Puddingstone is an earth dam located in Los Angeles County, California, built in 1928. It carries a High hazard potential classification and has a satisfactory condition assessment.
About Puddingstone
The primary purpose of Puddingstone 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 Los Angeles County Department Of Public Works (local government). It impounds the Walnut Creek near San Dimas.
The dam stands 147 feet tall and stretches 2,698 feet across, creates a reservoir covering 490 acres, has a maximum storage capacity of 16,342 acre-feet, and collects water from a drainage area of 33 square miles. Completed in 1928, the structure is well-established, with more than 75 years of service.
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 10/22/2025.
At 147 feet, this dam is taller than 99% of all dams in the United States.
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 | Walnut Creek |
| Coordinates | 34.09090, -117.80840 |
Physical Characteristics
| Dam Type | Earth |
| NID Height | 147 ft |
| Dam Height | 147 ft |
| Dam Length | 2,698 ft |
| Year Completed | 1928 (98 years old) |
Storage & Hydraulics
| NID Storage | 16,342 acre-ft |
| Max Storage | 16,342 acre-ft |
| Surface Area | 490 acres |
| Drainage Area | 33 sq mi |
| Max Discharge | 28,970 cfs |
Ownership & Safety
| Purpose | Flood Risk Reduction |
| Owner | Los Angeles County Department Of Public Works |
| Owner Type | Local Government |
| Hazard Classification | High |
| Condition Assessment | Satisfactory |
| Last Inspection | 10/22/2025 |
| Emergency Action Plan | Yes |
Identifiers
| NID ID | CA00194 |
| Federal ID | CA00194 |
| More Info | State Dam Safety Program |