Rock Island
Hydro power plant · Chelan County, Washington
Nameplate capacity
629 MW
Rank in Washington
#14
of 139 plants
In service since
1931
October 1931
Details
- Primary fuel
- Hydro
- Technology
- Conventional Hydroelectric
- Operator
- PUD No 1 of Chelan County
- County
- Chelan County
- Generating units
- 19
- Share of state capacity
- 1.98%
- Rank among hydro plants in Washington
- #11 of 73
- EIA plant code
- 6200
Generating units
| Unit | Technology | Nameplate | Summer | Online | Status |
|---|---|---|---|---|---|
| U-1 | Conventional Hydroelectric | 51 MW | 42 MW | 1979 | Operating |
| U-2 | Conventional Hydroelectric | 51 MW | 42 MW | 1979 | Operating |
| U-3 | Conventional Hydroelectric | 51 MW | 42 MW | 1979 | Operating |
| U-4 | Conventional Hydroelectric | 51 MW | 42 MW | 1979 | Operating |
| U-5 | Conventional Hydroelectric | 51 MW | 42 MW | 1978 | Out of service and NOT expected to return to service in next calendar year |
| U-6 | Conventional Hydroelectric | 51 MW | 42 MW | 1978 | Operating |
| U-7 | Conventional Hydroelectric | 51 MW | 42 MW | 1978 | Operating |
| U-8 | Conventional Hydroelectric | 51 MW | 42 MW | 1978 | Operating |
| B-10 | Conventional Hydroelectric | 23 MW | 19 MW | 1953 | Operating |
| B-5 | Conventional Hydroelectric | 23 MW | 17 MW | 1952 | Operating |
| B-6 | Conventional Hydroelectric | 23 MW | 17 MW | 1952 | Operating |
| B-7 | Conventional Hydroelectric | 23 MW | 17 MW | 1952 | Operating |
| B-8 | Conventional Hydroelectric | 23 MW | 17 MW | 1953 | Out of service and NOT expected to return to service in next calendar year |
| B-9 | Conventional Hydroelectric | 23 MW | 19 MW | 1953 | Operating |
| B-1 | Conventional Hydroelectric | 21 MW | 15 MW | 1931 | Out of service and NOT expected to return to service in next calendar year |
| B-2 | Conventional Hydroelectric | 21 MW | 15 MW | 1931 | Out of service and NOT expected to return to service in next calendar year |
| B-3 | Conventional Hydroelectric | 21 MW | 15 MW | 1932 | Operating |
| B-4 | Conventional Hydroelectric | 21 MW | 15 MW | 1932 | Operating |
| A | Conventional Hydroelectric | 1.2 MW | 1.2 MW | 1931 | Operating |
Nameplate is the maximum rated output; summer capacity is what the unit can reliably deliver on a hot day, which is typically lower.
Similarly sized plants in Washington
| Transalta Centralia Generation | Coal | 730 MW |
| Grays Harbor Energy Facility | Natural gas | 715 MW |
| Ice Harbor | Hydro | 603 MW |
| Chehalis Generating Facility | Natural gas | 593 MW |
About this data
From EIA’s inventory of operable generators, May 2026 release. Capacity is nameplate — the maximum rated output of the equipment, not what the plant actually generates over a year, which depends on how often it runs. A 629 MW solar plant and a 629 MW nuclear plant have the same entry here and produce very different amounts of electricity.
“In service since” is the earliest in-service date among the units still listed, so a site rebuilt around newer equipment can read as younger than the site itself. All Washington power plants · What Washington actually generates