Mayfield
Hydro power plant in Lewis County, Washington. 162 MW of nameplate capacity across 4 generators, operated by City of Tacoma - (WA).
Also known as Mayfield Power Plant · EIA plant 3917
Analyst: free account, 1 question a day.
Key facts
- Capacity
- 162 MWNameplate
- Generators
- 4 operatingEIA-860M, August 2026
- Operating since
- March 1963First generator online
- Operator
- City of Tacoma - (WA)EIA operator ID 18429
- Grid
- TPWRBalancing authority TPWR
- Price nodes
- None linkedNo verified ISO node
- Location
- Lewis County, WA46.5035, −122.5885
- EIA plant ID
- 3917EIA plant page
Data as of EIA-860M August 2026 (published 2026-09-24). Capacity is nameplate, not live output.
How much power Mayfield produces
Free · EIA-923Net generation, 2025
603 GWh
602,506 MWh, final
Capacity factor, 2025
42.5%
2024: 40.5%
January to July 2026
Not reported
Provisional. 0 of 7 months reported
Range, 2015 to 2025
448.8–870.9
GWh a year. Low 2019, high 2017
| Year | Net generation, MWh | Capacity factor | Months reported |
|---|---|---|---|
| 2000 | 668,501 | Not reported | 12 of 12 |
| 2001 | 430,095 | Not reported | 12 of 12 |
| 2002 | 688,438 | Not reported | 12 of 12 |
| 2003 | 646,292 | Not reported | 12 of 12 |
| 2004 | 809,530 | Not reported | 12 of 12 |
| 2005 | 748,707 | Not reported | 12 of 12 |
| 2006 | 749,187 | Not reported | 12 of 12 |
| 2007 | 647,229 | Not reported | 12 of 12 |
| 2008 | 729,626 | Not reported | 12 of 12 |
| 2009 | 75,281 | Not reported | 12 of 12 |
| 2010 | 695,270 | 49.0% | 12 of 12 |
| 2011 | 828,501 | 58.4% | 12 of 12 |
| 2012 | 903,472 | 63.5% | 12 of 12 |
| 2013 | 714,522 | 50.3% | 12 of 12 |
| 2014 | 821,794 | 57.9% | 12 of 12 |
| 2015 | 621,103 | 43.8% | 12 of 12 |
| 2016 | 784,801 | 55.2% | 12 of 12 |
| 2017 | 870,878 | 61.4% | 12 of 12 |
| 2018 | 645,975 | 45.5% | 12 of 12 |
| 2019 | 448,832 | 31.6% | 12 of 12 |
| 2020 | 725,576 | 51.0% | 12 of 12 |
| 2021 | 724,784 | 51.1% | 12 of 12 |
| 2022 | 769,305 | 54.2% | 12 of 12 |
| 2023 | 545,006 | 38.4% | 12 of 12 |
| 2024 | 576,354 | 40.5% | 12 of 12 |
| 2025 | 602,506 | 42.5% | 12 of 12 |
| 2026 (provisional, partial year) | Not reported | Not reported | 0 of 7 |
* 2026 covers January to July and is provisional. Capacity factor is net generation divided by nameplate capacity times the hours of each reported month.
Power prices and basis
Free accountNo verified ISO price node is linked to this plant, or its price history could not load.
Emissions
Free · EPA CAMPDNo EPA emissions units are linked to this plant.
Water use
Free · EIA-923 cooling, USGSNo EIA cooling-water record for this plant in 2024. Plants without steam cooling, such as wind, solar and batteries, do not report cooling water.
Generators
Free · EIA-860M| Generator | Technology | Nameplate MW | Online since |
|---|---|---|---|
| 41 | Conventional Hydroelectric | 40.5 | May 1983 |
| 42 | Conventional Hydroelectric | 40.5 | March 1963 |
| 43 | Conventional Hydroelectric | 40.5 | April 1963 |
| 44 | Conventional Hydroelectric | 40.5 | June 1963 |
Ownership and offtake
ProOwnership and offtake are part of Pro
Owners and their shares, parent companies, and power purchase agreements with their buyers. EIA-860M lists City of Tacoma - (WA) as the operator, which is not always the owner.
Modeled data
ProPro adds modeled values for this plant. Everything above stays free.
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Power plants near Mayfield
More plants operated by City of Tacoma - (WA)
Questions about Mayfield
How much power does Mayfield produce?
Mayfield reported 602,506 MWh (603 GWh) of net generation in 2025, a 42.5% capacity factor on 162 MW of nameplate capacity.
Where is Mayfield?
Mayfield is in Lewis County, Washington, at 46.5035, −122.5885. It is in the City of Tacoma, Department of Public Utilities, Light Division balancing area (TPWR).
Who operates Mayfield?
EIA-860M for August 2026 lists City of Tacoma - (WA) as the operator (EIA operator ID 18429). The operator is not always the owner.
When did Mayfield start operating?
Its first generator began operating in March 1963, according to EIA-860M.
Sources
- EIA-860 2025 (final) and EIA-860M August 2026: plant, generators, capacity, operator and location
- EIA-923 monthly net generation, 2000 to July 2026 (2026 provisional)
- Plant names from OpenStreetMap, © OpenStreetMap contributors (ODbL)
Page updated 2026-10-04 from the InfraMap data build. Methodology · Data sources · EIA plant page