The amount of hydroelectric electricity generation used by California is impacted by regional precipitation, transmission availability, and electricity demand.

Data reported to the Energy Commission through the Quarterly Fuels and Energy Report (QFER) show California's hydroelectric facilities declining generation over the past 20 years. Preliminary analyses indicate these declines are not attributable to loss of capacity from decommissioned facilities, efficiency losses due to sediment deposition, or operational issues.

Imports of hydroelectric generation have steadily increased in the recent years. As California moves towards a 100 percent clean energy goal, these imports will likely remain high but generation could also be impacted by variable weather and changing regional demand in the Western interconnection.

Dashboard is best viewed from a computer.  Visit Tableau for the full page layout of dashboard or download data, or return to dashboard collection page. 

Other Dashboards in this Collection:
Estimated Annual Clean Energy | Large Hydroelectric Trends| Nuclear Trends

Generation (GWh):
The annual amount of electricity generated in gigawatt hours.

Gigawatt hour is an electric unit of measurement equal to one million watts of power supplied to, or taken from, an electric circuit steadily for one hour.

Large Hydroelectric Resources:
Large hydroelectric generation facilities with nameplate capacities over 30 MW categorized into in-state generation and imported generation resources.

Power Source Disclosure (PSD):
The PSD Power Source Disclosure program was established by Senate Bill (SB) 1305 (Stats. 1997, ch. 796) in an effort to provide retail electricity consumers “accurate, reliable, and simple to understand information on the sources of energy that are used to provide electric services.” This program provides consumers a detailed view into the sources of energy purchased and associated greenhouse gas emissions by their retail suppliers to power their homes and businesses.

Quarterly Fuels and Energy Report (QFER):
The set of data collection regulations that collect California electric generation, control area exchanges, and natural gas processing and deliveries. Electricity generation data is collected for power plants with nameplate capacities greater than 1MW located within California or within a control area with California end users. 

The quantity of large hydroelectric generation produced for California from 2002 to 2022 are shown.

Trend lines are presented from 2004 to 2022 and shows the three-year floating average value.

Data last updated: 5/9/2024

Data Collection Information
Source of data was collected from Energy Commission data submittals including QFER, RPS, and PSD data sources and external data sources.

Please cite use of these data and images. California Energy Commission 2023. California Energy Commission Large Hydroelectric Historical Trends. Data last updated [insert date last updated]. Retrieved [insert date retrieved] from


Media and Public Communication Office