DONNELLS
OperatingHydro power plant
- Capacity
- 72 MW
- Primary fuel
- Hydro
- County
- Tuolumne County
- Operator
- OAKDALE&SOUTH SAN JOAQUIN IRRIGATION D.
- Status
- Operating
- Commissioned
- 1957
- EIA plant ID
- 415
- Generators
- 1
- Technology
- Conventional Hydroelectric
- Net generation (2024)
- 219 GWh
- Capacity factor (2024, EIA nameplate)
- 35%
- Data vintage
- EIA-860 2024 final; EIA-923 2022-2024 final
- Coordinates
- 38.2467, -120.0341
DONNELLS, a 72 MW Hydro power plant in Tuolumne County, California. Operated by OAKDALE&SOUTH SAN JOAQUIN IRRIGATION D., commissioned 1957.
How DONNELLS compares
With 72 MW of capacity, DONNELLS ranks 202nd among the 874 operating power plants Bywatts maps in California and 53rd of the 195 operating Hydro plants in the state. It accounts for about 0.5% of California's operating Hydro capacity and 0.1% of all operating capacity in the state. Nationally it is the 228th-largest of the 1,243 operating Hydro plants in the database. Commissioned in 1957, it is older than 91% of the 859 operating California plants with a recorded commissioning year. Its operator, OAKDALE&SOUTH SAN JOAQUIN IRRIGATION D., runs 3 operating plants in California totaling 109 MW. It shares Tuolumne County with 16 other operating plants, including NEW MELONES and DON PEDRO.
EIA-860 lists 1 generator at the site with 72 MW of nameplate capacity, all conventional hydroelectric technology. Net generation was 219 GWh in 2024 (a 35% capacity factor), up 8% from 2022.
Grid neighborhood
The nearest named substation is DONNELLS-CURTIS (115 kV), under 0.1 miles away; the closest transmission line found within 10 miles is a 115 kV line owned by PACIFIC GAS & ELECTRIC COMPANY, under 0.1 miles away. Another 10 operating power plants totaling 593 MW sit within 25 miles; the largest is COLLIERVILLE POWERHOUSE (253 MW, Hydro).
Computed by Bywatts from HIFLD power plant, substation and transmission line records and EIA-860/923 survey data; distances are straight-line. Sources and methodology
Weather peril exposure
DONNELLS is a 72 MW hydro power plant in Tuolumne County, CA, operated by OAKDALE&SOUTH SAN JOAQUIN IRRIGATION D., commissioned in 1957. Tuolumne County carries low modeled catastrophe exposure in the FEMA National Risk Index, scoring 1.7 of 5 at the 17th national percentile. Wildfire is the leading peril, rated Relatively High by FEMA at the 99th percentile.
The Bywatts loss layer is calibrated to solar PV hardware, so it is not applied to a hydro plant. The ratings below are the FEMA National Risk Index county hazard ratings for this location.
Tuolumne County hazard ratings
| Peril | FEMA rating | National percentile | Peril score | Events per year |
|---|---|---|---|---|
| Wildfire | Relatively High | 99th | 4.9 of 5 | 0.01 |
| Riverine flooding | Relatively Moderate | 86th | 4.4 of 5 | 0.96 |
| Heat wave | Relatively Moderate | 72nd | 3.9 of 5 | 3.3 |
| Earthquake | Relatively Low | 69th | 3.8 of 5 | 0.02 |
| Winter weather | Relatively Moderate | 31st | 2.2 of 5 | 33.0 |
| Lightning | Relatively Moderate | 18th | 1.7 of 5 | 20.3 |
| Strong wind | Very Low | 14th | 1.6 of 5 | 0.05 |
| Tornado | Very Low | 5th | 1.2 of 5 | 0.13 |
| Hail | Very Low | 1st | 1.0 of 5 | 0.11 |
Perils not assessed in Tuolumne County
These perils carry no usable National Risk Index figure for this county, so they are excluded from the scoring rather than scored zero. A zero would claim the peril was assessed and found benign.
| Peril | Why it is not scored |
|---|---|
| Hurricane | FEMA rating is "Not Applicable" for this county |
| Coastal flooding | FEMA rating is "Not Applicable" for this county |
| Ice storm | FEMA rating is "Not Applicable" for this county |
Model hail, wind and flood exposure for Tuolumne County in the weather risk calculator
Ratings are the FEMA National Risk Index county hazard ratings; the peril score is a Bywatts transform of the FEMA national percentile. Full data sources and the solar vulnerability methodology are in the weather risk calculator.
Modeled estimate for screening and negotiation. Built from FEMA National Risk Index county hazard data and a solar vulnerability layer documented above. Not a quote, a binder, or actuarial advice, and not a substitute for a carrier's own model. Hazard data: FEMA National Risk Index December 2025, synced 2026-07-24. Resolution is county level, not site level.