South Fork Tolt
King County, Washington · EIA plant ID 622 · Operator: City of Seattle - (WA)
Nameplate17MWSummer 17 MW
Generators1in service
Net generation49GWh12 mo to Dec 2025
Capacity factor33%hydro units, summer MW
Heat rate—thermal plants only
First online1995
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 | 39.7 | 27.0% | — |
| 2002 | 77.9 | 52.9% | — |
| 2003 | 48.7 | 33.1% | — |
| 2004 | 60.4 | 41.0% | — |
| 2005 | 44.8 | 30.4% | — |
| 2006 | 53.5 | 36.4% | — |
| 2007 | 55.8 | 37.9% | — |
| 2008 | 57.1 | 39.4% | — |
| 2009 | 50.5 | 34.9% | — |
| 2010 | 53.8 | 36.5% | — |
| 2011 | 49.8 | 33.8% | — |
| 2012 | 63 | 42.7% | — |
| 2013 | 55.3 | 37.6% | — |
| 2014 | 63.3 | 43.0% | — |
| 2015 | 48.8 | 33.2% | — |
| 2016 | 52.1 | 35.3% | — |
| 2017 | 54.5 | 37.1% | — |
| 2018 | 58.3 | 39.6% | — |
| 2019 | 29.3 | 19.9% | — |
| 2020 | 42 | 28.4% | — |
| 2021 | 54.4 | 37.0% | — |
| 2022 | 58.5 | 39.7% | — |
| 2023 | 30.1 | 20.5% | — |
| 2024 | 44.6 | 30.2% | — |
| 2025 | 48.6 | 33.0% | — |
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 |
|---|---|---|---|---|---|---|---|---|
| 1 | Conventional Hydroelectric | HY | 16.8 | 16.8 | Nov 1995 | Operating | — | coming soon |
Owner / operator
Operator: City of Seattle - (WA). Ownership shares by in-service nameplate MW (EIA-860 Schedule 4; units not listed there are wholly owned by the operator).
| City of Seattle - (WA) | 100.0% | 17 MW |
Nearby plants
Within 80 km.
| Youngs Creek Hydroelectric Project | 8 MW | 10.4 km |
| Calligan Creek Hydroelectric Project | 6 MW | 13 km |
| Hancock Creek Hydroelectric Project | 6 MW | 15.8 km |
| Snoqualmie 2 | 39 MW | 17.7 km |
| Snoqualmie | 13 MW | 18.1 km |
| Black Creek | 4 MW | 22.8 km |