Hydropower supplied a majority of the electricity generated in Washington in every year from 2001 through 2025. The share averaged 68.9%, peaked at 79.7% in 2011, and fell to 59.7% in 2023 and 59.3% in 2024, during drought emergencies, before rising to 63.6% in 2025. The share has drifted down over time: it averaged 71.0% in 2001-2010 and 65.1% in 2016-2025.
| date | hydro_share_pct | series | year |
|---|---|---|---|
| 2001-01-01 | 65.9 | Hydro share of in-state net generation | 2001 |
| 2002-01-01 | 76.1 | Hydro share of in-state net generation | 2002 |
| 2003-01-01 | 71.7 | Hydro share of in-state net generation | 2003 |
| 2004-01-01 | 70.1 | Hydro share of in-state net generation | 2004 |
| 2005-01-01 | 70.7 | Hydro share of in-state net generation | 2005 |
| 2006-01-01 | 75.8 | Hydro share of in-state net generation | 2006 |
| 2007-01-01 | 73.7 | Hydro share of in-state net generation | 2007 |
| 2008-01-01 | 70.1 | Hydro share of in-state net generation | 2008 |
| 2009-01-01 | 69.8 | Hydro share of in-state net generation | 2009 |
| 2010-01-01 | 66 | Hydro share of in-state net generation | 2010 |
| 2011-01-01 | 79.7 | Hydro share of in-state net generation | 2011 |
| 2012-01-01 | 76.6 | Hydro share of in-state net generation | 2012 |
| 2013-01-01 | 68.5 | Hydro share of in-state net generation | 2013 |
| 2014-01-01 | 68.3 | Hydro share of in-state net generation | 2014 |
| 2015-01-01 | 67.2 | Hydro share of in-state net generation | 2015 |
| 2016-01-01 | 68.7 | Hydro share of in-state net generation | 2016 |
| 2017-01-01 | 70.9 | Hydro share of in-state net generation | 2017 |
| 2018-01-01 | 69.3 | Hydro share of in-state net generation | 2018 |
| 2019-01-01 | 62 | Hydro share of in-state net generation | 2019 |
| 2020-01-01 | 65.8 | Hydro share of in-state net generation | 2020 |
| 2021-01-01 | 64.4 | Hydro share of in-state net generation | 2021 |
| 2022-01-01 | 67.6 | Hydro share of in-state net generation | 2022 |
| 2023-01-01 | 59.7 | Hydro share of in-state net generation | 2023 |
| 2024-01-01 | 59.3 | Hydro share of in-state net generation | 2024 |
| 2025-01-01 | 63.6 | Hydro share of in-state net generation | 2025 |