SUMMER FALLS POWER PLANT
OperatingHydro power plant
- Capacity
- 92 MW
- Primary fuel
- Hydro
- County
- Grant County
- Operator
- GRAND COULEE PROJECT HYDROELECTRIC AUTH
- Status
- Operating
- Commissioned
- 1985
- EIA plant ID
- 56695
- Generators
- 2
- Technology
- Conventional Hydroelectric
- Net generation (2024)
- 398 GWh
- Capacity factor (2024, EIA nameplate)
- 49%
- Data vintage
- EIA-860 2024 final; EIA-923 2022-2024 final
- Coordinates
- 47.5025, -119.2920
SUMMER FALLS POWER PLANT, a 92 MW Hydro power plant in Grant County, Washington. Operated by GRAND COULEE PROJECT HYDROELECTRIC AUTH, commissioned 1985.
How SUMMER FALLS POWER PLANT compares
With 92 MW of capacity, SUMMER FALLS POWER PLANT ranks 53rd among the 126 operating power plants Bywatts maps in Washington and 23rd of the 65 operating Hydro plants in the state. It accounts for about 0.4% of Washington's operating Hydro capacity and 0.3% of all operating capacity in the state. Nationally it is the 192nd-largest of the 1,243 operating Hydro plants in the database. Commissioned in 1985, it is newer than 48% of the 125 operating Washington plants with a recorded commissioning year. Its operator, GRAND COULEE PROJECT HYDROELECTRIC AUTH, runs 5 operating plants in Washington totaling 129 MW. It shares Grant County with 6 other operating plants, including GRAND COULEE and WANAPUM.
EIA-860 lists 2 generators at the site with 92 MW of nameplate capacity, all conventional hydroelectric technology. Net generation was 398 GWh in 2024 (a 49% capacity factor), about the same as in 2022.
Grid neighborhood
The nearest named substation is STRATFORD, about 5.5 miles away; the closest transmission line found within 10 miles is a 115 kV line owned by AVISTA CORP, under 0.1 miles away. One other operating power plant sits within 25 miles: MAIN CANAL HEADWORKS (27 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
SUMMER FALLS POWER PLANT is a 92 MW hydro power plant in Grant County, WA, operated by GRAND COULEE PROJECT HYDROELECTRIC AUTH, commissioned in 1985. Grant County carries low modeled catastrophe exposure in the FEMA National Risk Index, scoring 1.1 of 5 at the 2nd national percentile. Wildfire is the leading peril, rated Relatively Moderate by FEMA at the 93rd 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.
Grant County hazard ratings
| Peril | FEMA rating | National percentile | Peril score | Events per year |
|---|---|---|---|---|
| Wildfire | Relatively Moderate | 93rd | 4.7 of 5 | <0.01 |
| Earthquake | Relatively Low | 83rd | 4.3 of 5 | <0.01 |
| Heat wave | Relatively Moderate | 63rd | 3.5 of 5 | 4.7 |
| Riverine flooding | Relatively Moderate | 22nd | 1.9 of 5 | 0.36 |
| Winter weather | Relatively Moderate | 17th | 1.7 of 5 | 9.7 |
| Lightning | Relatively Low | 10th | 1.4 of 5 | 9.2 |
| Strong wind | Relatively Low | 10th | 1.4 of 5 | 0.17 |
| Tornado | Very Low | 6th | 1.2 of 5 | 0.10 |
| Hail | Relatively Low | 2nd | 1.1 of 5 | 0.11 |
| Ice storm | Very Low | 0th | 1.0 of 5 | 0.01 |
Perils not assessed in Grant 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 |
Model hail, wind and flood exposure for Grant 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.