Twin Reservoirs
Walla Walla County, Washington · EIA plant ID 50382 · Operator: Walla Walla City of
Nameplate2MWSummer 2 MW
Generators1in service
Net generation7GWh12 mo to Dec 2025
Capacity factor44%hydro units, summer MW
Heat rate—thermal plants only
First online1988
Monthly net generation
EIA-923, all units at the plant. Net of station use; storage can go negative.
FinalPreliminary
Capacity factor by year
Net MWh ÷ (summer MW × hours), hydro units. Each year uses that year's EIA-860 ratings; the hollow dot is the latest 12 months.
Heat rate by year
Electric fuel MMBtu × 1000 ÷ net MWh (Btu/kWh, HHV), fossil units only; CT + CA counted as one combined-cycle block.
Heat rate applies to fuel-burning (thermal) units only.
Annual data table
| Year | Net GWh | Capacity factor | Heat rate (Btu/kWh) |
|---|---|---|---|
| 2001 | 14 | 106.8% | — |
| 2002 | 12.1 | 92.4% | — |
| 2003 | 10.8 | 81.9% | — |
| 2004 | 12.7 | 80.3% | — |
| 2005 | 11.3 | 71.5% | — |
| 2006 | 12.4 | 78.6% | — |
| 2007 | 12.4 | 78.5% | — |
| 2008 | 13.1 | 82.7% | — |
| 2009 | 12.3 | 77.8% | — |
| 2010 | 12.1 | 77.0% | — |
| 2011 | 13.3 | 84.1% | — |
| 2012 | 13.6 | 86.3% | — |
| 2013 | 12.8 | 81.4% | — |
| 2014 | 11.8 | 75.0% | — |
| 2015 | 11.7 | 73.9% | — |
| 2016 | 12 | 75.7% | — |
| 2017 | 11.9 | 75.6% | — |
| 2018 | 11.5 | 72.7% | — |
| 2019 | 8.1 | 51.5% | — |
| 2020 | 8.4 | 53.4% | — |
| 2021 | 10.9 | 69.0% | — |
| 2022 | 9.4 | 59.5% | — |
| 2023 | 8.1 | 51.6% | — |
| 2024 | 7.3 | 46.3% | — |
| 2025 | 6.9 | 43.5% | — |
Generators
EIA-860 (annual) with EIA-860M updates through Sep 2026. EIA-923 reports generation by plant, prime mover and fuel, not by unit, so unit-level output isn't shown.
| Gen ID | Technology | Prime mover | Nameplate MW | Summer MW | Online | Status | Planned retirement | OEM / model |
|---|---|---|---|---|---|---|---|---|
| GEN1 | Conventional Hydroelectric | HY | 2.2 | 1.8 | Apr 1988 | Operating | — | coming soon |
Owner / operator
Operator: Walla Walla City of. Ownership shares by in-service nameplate MW (EIA-860 Schedule 4; units not listed there are wholly owned by the operator).
| Walla Walla City of | 100.0% | 2 MW |
Nearby plants
Within 80 km.
| Schumann Wind Farm | 8 MW | 27.5 km |
| Chopin Wind LLC | 10 MW | 28.2 km |
| Eurus Combine Hills Turbine Ranch 2 | 66 MW | 30.6 km |
| Combine Hills I | 43 MW | 30.6 km |
| Vansycle II Wind Energy Center | 102 MW | 33.4 km |
| Vansycle | 25 MW | 35.6 km |