Diablo

500 Newhalem Street, Rockport, WA 98283

Plant Summary Information

Diablo is ranked #34 out of 131 power plants in Washington in terms of total annual net electricity generation.

Diablo is comprised of 4 generators and generated 208.2 GWh during the 3-month period between September 2025 to December 2025.

Plant Name	Diablo
Utility Name	City of Seattle - (WA)
Location	Whatcom County, WA
Initial Operation Date	October 1936
Last Update	Dec 2025
Annual Generation	518.2 GWh
Annual Consumption	1.8 M MMBtu
Ranked #1,318 out of 13,081 Power Plants Nationwide
Ranked #73 out of 1,311 Water Power Plants Nationwide
Ranked #34 out of 131 Washington Power Plants
Ranked #17 out of 70 Washington Water Power Plants
Fuel Types	Water

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Summary Information
Plant Name	Diablo (6432)
Plant Address	500 Newhalem Street, Rockport, WA 98283
Utility	City of Seattle - (WA) (16868)
Latitude, Longitude	48.71385, -121.13174
Generation Dates on File	Jan 2001 to Dec 2025
Initial Operation Date	October 1936
Annual Generation	518.2 GWh
Fuel Types	Water

Federal Energy Regulatory Commission (FERC) Information
FERC Cogeneration Status	No
FERC Small Power Producer Status	No
FERC Exempt Wholesale Generator Status	No

Regulatory Information
Regulatory Status	Regulated
NERC Region	WECC
Balancing Authority	Seattle City Light (SCL)
NAICS Code	Utilities (22)
Sector	Electric Utility (1)
Water Source	Skagit River
Ash Impoundment	No
Transmission / Distribution Owner	City of Seattle - (WA) (16868) WA
Grid Voltage	230.00 kV
Energy Storage	No

* Data obtained from the 2025 EIA 860 Report

Technology	Conventional Hydroelectric
Prime Mover	Hydroelectric Turbine
Ownership	Single Owner
RTO ISO LMP Node Designation	DIABLO_2_GEN32GNODE
RTO ISO Location Designation For Reporting Wholesale Sales Data	DIABLO_2_GEN32GNODE
Nameplate Capacity	90 MW
Nameplate Power Factor	0.9
Summer Capacity	90 MW
Winter Capacity	90 MW
Minimum Load	1 MW
Uprate/Derate Completed	No

Status	Operating
First Operation Date	October 1936
Combined Heat & Power	No
Sector Name	Electric Utility (1)
Energy Source	Water
Solid Fuel Gasification	No
Carbon Capture Technology	No
Time From Cold Shutdown To Full Load	1H
Other Planned Modifications	Yes
Other Modifications	October 2027
Multiple Fuels	No

Technology	Conventional Hydroelectric
Prime Mover	Hydroelectric Turbine
Ownership	Single Owner
Nameplate Capacity	1.2 MW
Nameplate Power Factor	0.8
Summer Capacity	1.2 MW
Winter Capacity	1.2 MW
Minimum Load	0.5 MW
Uprate/Derate Completed	No
Status	Operating

First Operation Date	October 1936
Combined Heat & Power	No
Sector Name	Electric Utility (1)
Energy Source	Water
Solid Fuel Gasification	No
Carbon Capture Technology	No
Time From Cold Shutdown To Full Load	1H
Other Planned Modifications	Yes
Other Modifications	July 2029
Multiple Fuels	No

Technology	Conventional Hydroelectric
Prime Mover	Hydroelectric Turbine
Ownership	Single Owner
Nameplate Capacity	1.2 MW
Nameplate Power Factor	0.8
Summer Capacity	1.2 MW
Winter Capacity	1.2 MW
Minimum Load	0.5 MW
Uprate/Derate Completed	No
Status	Operating

First Operation Date	October 1936
Combined Heat & Power	No
Sector Name	Electric Utility (1)
Energy Source	Water
Solid Fuel Gasification	No
Carbon Capture Technology	No
Time From Cold Shutdown To Full Load	1H
Other Planned Modifications	Yes
Other Modifications	December 2029
Multiple Fuels	No

Technology	Conventional Hydroelectric
Prime Mover	Hydroelectric Turbine
Ownership	Single Owner
RTO ISO LMP Node Designation	DIABLO_2_GEN31GNODE
RTO ISO Location Designation For Reporting Wholesale Sales Data	DIABLO_2_GEN31GNODE
Nameplate Capacity	90 MW
Nameplate Power Factor	0.9
Summer Capacity	90 MW
Winter Capacity	90 MW
Minimum Load	1 MW
Uprate/Derate Completed	No

Status	Operating
First Operation Date	April 1937
Combined Heat & Power	No
Sector Name	Electric Utility (1)
Energy Source	Water
Solid Fuel Gasification	No
Carbon Capture Technology	No
Time From Cold Shutdown To Full Load	1H
Other Planned Modifications	Yes
Other Modifications	June 2027
Multiple Fuels	No

Owner Name	Address	Generator	Ownership
*We couldn't locate any owners for this plant*

Power plants with a similar annual net generation from Water.

Rank	Plant Name	Plant Location	Annual Generation
#63	Barkley	Kuttawa, KY	624.9 GWh
#64	Mayfield	Silver Creek, WA	602.5 GWh
#65	Dion R Holm	Groveland, CA	577.8 GWh
#66	Nickajack	New Hope, TN	577.6 GWh
#67	Calderwood	Tallassee, TN	568.7 GWh
#68	Mammoth Pool	North Fork, CA	568.6 GWh
#69	Yellowtail	Hardin, MT	566.2 GWh
#70	J Strom Thurmond	Clarks Hill, SC	566.0 GWh
#71	Folsom	Folsom, CA	537.6 GWh
#72	James B Black	Big Bend, CA	530.6 GWh
#74	Dardanelle	Dardanelle, AR	517.3 GWh
#75	Guntersville	Guntersville, AL	509.1 GWh
#76	Swift 1	Cougar, WA	508.0 GWh
#77	Great Lakes Hydro America - ME	Millinocket, ME	500.1 GWh
#78	Osage Dam	Eldon, MO	498.9 GWh
#79	R C Kirkwood	Groveland, CA	489.0 GWh
#80	Lay Dam	Clanton, AL	482.4 GWh
#81	Trinity	Weaverville, CA	475.6 GWh
#82	Yale	Amboy, WA	472.5 GWh
#83	Cheoah	Tapoco, NC	472.4 GWh

Below are closest 20 power plants surrounding Diablo.

Plant Name	Plant Location	Annual Generation	Distance
Arlington Microgrid	Arlington, WA	601.0 MWh	60.5 mi
Chelan	Wenatchee, WA	325.2 GWh	79.6 mi
Darrington	Darrington, WA	12.3 GWh	37.4 mi
Encogen	Bellingham, WA	236.9 GWh	61.8 mi
Ferndale Generating Station	Ferndale, WA	737.5 GWh	71.2 mi
Fredonia (WA)	Mt Vernon, WA	60.4 GWh	62.2 mi
Gorge	Rockport, WA	912.4 GWh	3.7 mi
H M Jackson	Sultan, WA	333.6 GWh	63.9 mi
HF Sinclair Puget Sound Refining	Anacortes, WA	896.6 GWh	67.4 mi
Koma Kulshan	Concrete, WA	32.3 GWh	27.1 mi
Lower Baker	Concrete, WA	364.8 GWh	30.1 mi
Nooksack Hydro	Glacier, WA	20.2 GWh	33.8 mi
Ross	Rockport, WA	714.9 GWh	3.2 mi
Sierra Pacific Burlington Facility	Mt Vernon, WA	160.2 GWh	62.3 mi
South Fork Tolt	North Bend, WA	48.6 GWh	76.3 mi
Sumas Power Plant	Sumas, WA	675.8 GWh	55.3 mi
Upper Baker	Concrete, WA	332.7 GWh	25.9 mi
Wells	Chelan, WA	4.3 TWh	78.7 mi
Whitehorn	Blaine, WA	65.2 GWh	74.7 mi
Youngs Creek Hydroelectric Project	Monroe, WA	12.9 GWh	70.7 mi