Upper Wilcox
Upper Wilcox is an earth dam located in Madera County, California, built in 1930. It carries a High hazard potential classification and has a satisfactory condition assessment.
About Upper Wilcox
The primary purpose of Upper Wilcox is irrigation. The dam stores and diverts water for agricultural irrigation, supporting farming operations in the surrounding area. The dam is owned by C.b.s. Development Corporation (private). It impounds the Unnamed Tributary To Picayunne Creek.
The dam stands 48 feet tall and stretches 840 feet across, creates a reservoir covering 13 acres, has a maximum storage capacity of 200 acre-feet, and collects water from a drainage area of 0 square miles. Completed in 1930, the structure is well-established, with more than 75 years of service.
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 05/28/2025.
At 48 feet, this dam is taller than 92% 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 | Madera |
| River/Stream | Unnamed Tributary To Picayunne Creek |
| Coordinates | 37.22550, -119.68490 |
Physical Characteristics
| Dam Type | Earth |
| NID Height | 48 ft |
| Dam Height | 48 ft |
| Dam Length | 840 ft |
| Year Completed | 1930 (96 years old) |
Storage & Hydraulics
| NID Storage | 200 acre-ft |
| Max Storage | 200 acre-ft |
| Surface Area | 13 acres |
| Drainage Area | 0 sq mi |
Ownership & Safety
| Purpose | Irrigation |
| Owner | C.B.S. Development Corporation |
| Owner Type | Private |
| Hazard Classification | High |
| Condition Assessment | Satisfactory |
| Last Inspection | 05/28/2025 |
| Emergency Action Plan | Yes |
Identifiers
| NID ID | CA01450 |
| Federal ID | CA01450 |
| More Info | State Dam Safety Program |