Lake Madigan
Lake Madigan is an earth dam located in Solano County, California, built in 1908. It carries a High hazard potential classification and has a satisfactory condition assessment.
About Lake Madigan
The primary purpose of Lake Madigan 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 Vallejo (local government). It impounds the Wild Horse Creek near Green Valley.
The dam stands 89 feet tall and stretches 665 feet across, creates a reservoir covering 72 acres, has a maximum storage capacity of 1,175 acre-feet, and collects water from a drainage area of 1 square miles. Completed in 1908, 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 09/30/2025.
At 89 feet, this dam is taller than 97% 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 | Solano |
| Nearest City | Green Valley |
| River/Stream | Wild Horse Creek |
| Coordinates | 38.30740, -122.19390 |
Physical Characteristics
| Dam Type | Earth |
| NID Height | 89 ft |
| Dam Height | 89 ft |
| Dam Length | 665 ft |
| Year Completed | 1908 (118 years old) |
Storage & Hydraulics
| NID Storage | 1,175 acre-ft |
| Max Storage | 1,175 acre-ft |
| Surface Area | 72 acres |
| Drainage Area | 1 sq mi |
| Max Discharge | 3,670 cfs |
Ownership & Safety
| Purpose | Water Supply |
| Owner | City of Vallejo |
| Owner Type | Local Government |
| Hazard Classification | High |
| Condition Assessment | Satisfactory |
| Last Inspection | 09/30/2025 |
| Emergency Action Plan | Yes |
Identifiers
| NID ID | CA00141 |
| Federal ID | CA00141 |
| More Info | State Dam Safety Program |