Milliken
Milliken is an arch dam located in Napa County, California, built in 1924. It carries a High hazard potential classification and has a satisfactory condition assessment.
About Milliken
The primary purpose of Milliken 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 Napa (local government). It impounds the Milliken Creek near Napa.
The dam stands 110 feet tall and stretches 647 feet across, creates a reservoir covering 44 acres, has a maximum storage capacity of 1,980 acre-feet, and collects water from a drainage area of 9 square miles. Completed in 1924, 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 12/12/2024.
At 110 feet, this dam is taller than 98% 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 | Napa |
| Nearest City | Napa |
| River/Stream | Milliken Creek |
| Coordinates | 38.37730, -122.22890 |
Physical Characteristics
| Dam Type | Arch |
| NID Height | 110 ft |
| Dam Height | 110 ft |
| Dam Length | 647 ft |
| Year Completed | 1924 (102 years old) |
Storage & Hydraulics
| NID Storage | 1,980 acre-ft |
| Max Storage | 1,980 acre-ft |
| Surface Area | 44 acres |
| Drainage Area | 9 sq mi |
Ownership & Safety
| Purpose | Water Supply |
| Owner | City of Napa |
| Owner Type | Local Government |
| Hazard Classification | High |
| Condition Assessment | Satisfactory |
| Last Inspection | 12/12/2024 |
| Emergency Action Plan | Yes |
Identifiers
| NID ID | CA00102 |
| Federal ID | CA00102 |
| More Info | State Dam Safety Program |