Pomponio Ranch
Pomponio Ranch is an earth dam located in San Mateo County, California, built in 1952. It carries a High hazard potential classification and has a satisfactory condition assessment.
About Pomponio Ranch
Pomponio Ranch is a dam in San Mateo, California. The dam is owned by Scott Cook And Signe Ostby (private). It impounds the Pomponio Creek.
The dam stands 64 feet tall and stretches 245 feet across, creates a reservoir covering 13 acres, has a maximum storage capacity of 274 acre-feet, and collects water from a drainage area of 0 square miles. Completed in 1952, 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 08/19/2024.
At 64 feet, this dam is taller than 96% 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 | San Mateo |
| River/Stream | Pomponio Creek |
| Coordinates | 37.29028, -122.31342 |
Physical Characteristics
| Dam Type | Earth |
| NID Height | 64 ft |
| Dam Height | 64 ft |
| Dam Length | 245 ft |
| Year Completed | 1952 (74 years old) |
Storage & Hydraulics
| NID Storage | 274 acre-ft |
| Max Storage | 274 acre-ft |
| Surface Area | 13 acres |
| Drainage Area | 0 sq mi |
Ownership & Safety
| Purpose | Other |
| Owner | Scott Cook and Signe Ostby |
| Owner Type | Private |
| Hazard Classification | High |
| Condition Assessment | Satisfactory |
| Last Inspection | 08/19/2024 |
| Emergency Action Plan | Yes |
Identifiers
| NID ID | CA01008 |
| Federal ID | CA01008 |
| More Info | State Dam Safety Program |