Donnells
Donnells is a concrete dam located in Tuolumne County, California, built in 1958. It carries a High hazard potential classification and has a satisfactory condition assessment.
About Donnells
The primary purpose of Donnells is hydroelectric. The dam generates hydroelectric power by channeling water through turbines, converting the energy of flowing water into electricity. The dam is owned by South San Joaquin Irrigation District (public utility). It impounds the Middle Fork Stanislaus River near Sonora.
The dam stands 317 feet tall and stretches 750 feet across, creates a reservoir covering 418 acres, has a maximum storage capacity of 65,000 acre-feet, and collects water from a drainage area of 226 square miles. Completed in 1958, the structure is well into its service life at over 50 years 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 07/25/2023.
At 317 feet, this dam is taller than 99% 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 | Tuolumne |
| Nearest City | Sonora |
| River/Stream | Middle Fork Stanislaus River |
| Coordinates | 38.33054, -119.96099 |
Physical Characteristics
| Dam Type | Concrete |
| NID Height | 317 ft |
| Dam Height | 317 ft |
| Dam Length | 750 ft |
| Year Completed | 1958 (68 years old) |
Storage & Hydraulics
| NID Storage | 65,000 acre-ft |
| Max Storage | 65,000 acre-ft |
| Normal Storage | 64,500 acre-ft |
| Surface Area | 418 acres |
| Drainage Area | 226 sq mi |
| Max Discharge | 43,800 cfs |
| Spillway Type | Controlled |
Ownership & Safety
| Purpose | Hydroelectric |
| Owner | South San Joaquin Irrigation District |
| Owner Type | Public Utility |
| Hazard Classification | High |
| Condition Assessment | Satisfactory |
| Last Inspection | 07/25/2023 |
| Emergency Action Plan | Yes |
Identifiers
| NID ID | CA00264 |
| Federal ID | CA00264 |
| More Info | State Dam Safety Program |