Will Lake #1
Will Lake #1 is an earth dam located in Napa County, California, built in 2004. It carries a High hazard potential classification and has a satisfactory condition assessment.
About Will Lake #1
Will Lake #1 is a dam in Napa, California. The dam is owned by C. Mondavi And Son, Inc. (private). It impounds the Tr Napa River near City Of Napa.
The dam stands 40 feet tall and stretches 750 feet across, creates a reservoir covering 6 acres, has a maximum storage capacity of 89 acre-feet, and collects water from a drainage area of 0 square miles. Completed in 2004, the structure is relatively new.
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 01/13/2026.
At 40 feet, this dam is taller than 87% 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 | Napa |
| Nearest City | City Of Napa |
| River/Stream | Tr Napa River |
| Coordinates | 38.27710, -122.34070 |
Physical Characteristics
| Dam Type | Earth |
| NID Height | 40 ft |
| Dam Height | 40 ft |
| Dam Length | 750 ft |
| Year Completed | 2004 (22 years old) |
Storage & Hydraulics
| NID Storage | 89 acre-ft |
| Max Storage | 89 acre-ft |
| Surface Area | 6 acres |
| Drainage Area | 0 sq mi |
Ownership & Safety
| Purpose | Other |
| Owner | C. Mondavi and Son, Inc. |
| Owner Type | Private |
| Hazard Classification | High |
| Condition Assessment | Satisfactory |
| Last Inspection | 01/13/2026 |
| Emergency Action Plan | Yes |
Identifiers
| NID ID | CA01463 |
| Federal ID | CA01463 |
| More Info | State Dam Safety Program |