Lake Herman
Lake Herman is an earth dam located in Solano County, California, built in 1905. It carries a High hazard potential classification and has a satisfactory condition assessment.
About Lake Herman
The primary purpose of Lake Herman 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 City Of Benicia (local government). It impounds the Sulphur Springs Cr near Benicia.
The dam stands 51 feet tall and stretches 700 feet across, creates a reservoir covering 110 acres, and has a maximum storage capacity of 2,210 acre-feet. Completed in 1905, the structure is over a century 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 10/16/2025.
At 51 feet, this dam is taller than 93% of dams nationwide.
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 | Solano |
| Nearest City | Benicia |
| River/Stream | Sulphur Springs Cr |
| Coordinates | 38.09530, -122.15020 |
Physical Characteristics
| Dam Type | Earth |
| NID Height | 51 ft |
| Dam Height | 51 ft |
| Dam Length | 700 ft |
| Year Completed | 1905 (121 years old) |
Storage & Hydraulics
| NID Storage | 2,210 acre-ft |
| Max Storage | 2,210 acre-ft |
| Surface Area | 110 acres |
Ownership & Safety
| Purpose | Water Supply |
| Owner | City of Benicia |
| Owner Type | Local Government |
| Hazard Classification | High |
| Condition Assessment | Satisfactory |
| Last Inspection | 10/16/2025 |
| Emergency Action Plan | Yes |
Identifiers
| NID ID | CA00851 |
| Federal ID | CA00851 |
| More Info | State Dam Safety Program |