How big is Watson Cogeneration?

Watson Cogeneration has a reported capacity of 405 MW. Source: EIA Form 860.

What kind of plant is Watson Cogeneration?

Watson Cogeneration is a Natural Gas Fired Combined Cycle facility in Los Angeles County, CA, participating in the CAISO market.

Where is Watson Cogeneration located?

Watson Cogeneration is in Los Angeles County, CA, inside the CAISO balancing area.

Who operates Watson Cogeneration?

Watson Cogeneration is operated by ARCO Products Co-Watson according to the EIA generator inventory. Reporting membership does not by itself establish ultimate ownership.

How much electricity does Watson Cogeneration generate?

Watson Cogeneration reported 2,375.3 GWh over the twelve months to 2026-06. Figures are net generation as filed to EIA-923.

Where does Watson Cogeneration connect to the grid?

Watson Cogeneration interconnects at SCE Hinson Substation, on the Southern California Edison (SCE) system.

How does Watson Cogeneration compare to other plants?

By capacity, Watson Cogeneration ranks #326 of 538 operating plants of the same technology nationally. It ranks #24 of 64 in CA.

Watson Cogeneration — 405 MW gas plant, CA

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Watson Cogeneration — 405 MW gas plant, CA · Ask the Grid

Overview

Reported capacity: 405 MW
EIA-reported nameplate capacity; other nameplate and seasonal ratings may differ.
Technology: Natural Gas Fired Combined Cycle
Primary generation technology.
Registry anchor: Plant 50216
ARCO Products Co-Watson · Los Angeles County · CAISO
Operating status: Operating
Watson Cogeneration is operating.
Grid connection: SCE Hinson Substation
66 kV · Southern California Edison (SCE)
Commercial operation: April 1, 1988
Best-supported operating milestone.

Profile

Grid role: Industrial combined-heat-and-power cogeneration facility: electricity is sold to SCE and process steam is supplied to the adjacent refinery.
Grid connection: SCE Hinson Substation · 66 kV · Southern California Edison (SCE).
Context: Marathon Petroleum identifies the Watson cogeneration plant as the largest cogeneration facility in California; its refinery page states that the plant produces approximately 400 MW.
Physical build: Four parallel natural-gas combustion-turbine/HRSG trains and two parallel steam-turbine-driven power-generator trains, with associated auxiliaries, control room, electrical substation, and transmission line. The installed equipment identified in the sources is four GE Model 7EA gas turbines, four Vogt HRSGs, and two Dresser-Rand steam turbine generators.

Structured profile

Reported capacity: 405 MW
Natural Gas Fired Combined Cycle
Commercial operation: April 1, 1988
Operating status: operating
Watson Cogeneration is operating.
Interconnection: SCE Hinson Substation
66 kV · Southern California Edison (SCE)
Location: Los Angeles County
CAISO

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Units and generators

Operating generator records and technology attributes reported through EIA-860.

Generator	Capacity	Technology	Operation	Status
GN91	82 MW 82 MW summer	Natural Gas Fired Combined Cycle Natural Gas · CT	Mar 1988	Operating
GN92	82 MW 82 MW summer	Natural Gas Fired Combined Cycle Natural Gas · CT	Feb 1988	Operating
GN93	82 MW 82 MW summer	Natural Gas Fired Combined Cycle Natural Gas · CT	Jan 1988	Operating
GN94	82 MW 82 MW summer	Natural Gas Fired Combined Cycle Natural Gas · CT	Dec 1987	Operating
GN95

Performance

Monthly EIA generation history and recent market-resource behavior where linked telemetry is available.

Peer context

Technology capacity: 405 MW; Natural Gas Fired Combined Cycle
National rank: #326; of 538 operating peers
CA rank: #24; of 64 operating peers

Monthly generation

Download CSV

Latest 12 months

2.38 TWh

Reported net generation

Latest report

Jun 2026

EIA-923 monthly filing

2025 capacity factor

65.8%

Using current reported nameplate capacity

Grid and market context

Deterministic links to ERCOT market resources, price records, outage disclosures, queue records, and nearby infrastructure. Candidate joins remain labeled until corroborated.

Nearby substations

HIFLD infrastructure inventory

ARCOGEN

IN SERVICE · 230 kV

0.2 km

CARBONIC

Commercial, land, and environmental record

Source-backed project transactions, agreements, land records, permits, and environmental disclosures. Portfolio and adjacent-project facts remain explicitly scoped.

Transactions and agreements

Ownership Transfer

Jun 1988

California Energy Commission approved transfer of project ownership from ARCO Petroleum Products Company to Watson Cogeneration Company on June 22, 1988.

ARCO Petroleum Products Company · Watson Cogeneration Company

Watson Cogeneration Project | California Energy Commission

Partial Ownership Transfer

Jan 1997

California Energy Commission approved transfer of 49% of the 51% share held by Products Cogeneration Company to Carson Cogeneration Company on January 30, 1997.

Products Cogeneration Company · Carson Cogeneration Company

Watson Cogeneration Project | California Energy Commission

Acquisition

Jun 2013

Tesoro acquired BP's integrated Southern California refining, marketing, and logistics business including 51% ownership in Watson cogeneration facility. Broader Los Angeles Assets purchase price was $2.33 billion including $1.1 billion inventories; Watson portion not separately allocated.

Tesoro Corporation · BP West Coast Products LLC

Source

Upstream Ownership Change

Apr 2014

California Energy Commission records upstream ownership change. NRG Energy acquired Edison Mission Energy assets, including interest in Watson Cogeneration. Source does not disclose consideration allocated to Watson.

NRG Energy, Inc. · Edison Mission Energy

Watson Cogeneration Project | California Energy Commission

PPA Execution And Termination

Nov 17, 2014

SCE CHP-RFO PPA executed November 17, 2014 with online date July 1, 2015. SCE annual report lists 405.800 MW contract nameplate capacity. CPUC resolution separately describes Watson CHP as 385 MW. SCE 2022 report lists contract terminated June 30, 2022.

405.8 MW contractedWatson Cogeneration Company · Southern California Edison Company

Southern California Edison Company Energy Procurement & Management

Land and environmental record

Emissions Controls

2010

SCR, oxidation catalysts, CEMS for proposed fifth train; NOx 2.0 ppm limit, VOC 2.0 ppm limit

Air-permit record for proposed (uncompleted) fifth train identifies SCR for NOx control (2.0 ppm 1-hr avg BACT limit), CO oxidation catalyst, VOC oxidation catalyst (2.0 ppm limit), and CEMS under Rule 2012. Controls describe proposed unit, not constructed equipment.

Source

Environmental-Compliance Milestone

2024

2024 annual compliance reporting continued

CEC docket contains Annual Compliance Report for 2024 addressing cooling-tower blowdown, Dominguez Channel monitoring, and EPA/SCAQMD/CARB compliance for cooling-tower treatment chemicals.

Source

Hazardous Waste

Transported by DTSC-licensed haulers to permitted facilities

CEC compliance documentation states hazardous waste generated by APPC/Watson transported by California DTSC-licensed hazardous-waste hauler and disposed at permitted hazardous-waste facilities.

Source

Site Acreage

Apr 1, 1988

21.7 acres

Watson Cogeneration Project occupies 21.7 acres in Carson, Los Angeles County, adjacent to the refinery. Operational facility footprint established at project certification.

Watson Cogeneration Project | California Energy Commission

Wastewater Permit

2015

NPDES Order R4-2015-0259; NPDES No. CA0000680

Low-volume waste including cogeneration boiler blowdown authorized for discharge to Dominguez Channel under Tesoro Los Angeles Refinery—Carson Operations NPDES permit. Watson does not hold separate NPDES permit.

Source

Related parties and identifiers

Parties, market resources, and identifiers tied to this asset, with owner, operator, developer, EPC, compliance provider, and interconnecting entity roles kept separate.

Relationship graph

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AssetOwner / operator

Timeline and sources

Project milestones and public references behind the asset profile.

Project timeline

Sep 17, 1986
Sep 17, 1986
CEC CertificationWatson Coge...
The California Energy Commission certified the original Watson Cogeneration Project under docket 85-AFC-01.
Dec 1987
Dec 1987
Generators enter operation

Watson Cogeneration

Watson Cogeneration

Overview

Profile

Structured profile

Related assets

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Units and generators

Performance

Peer context

Monthly generation

Grid and market context

Nearby substations

Commercial, land, and environmental record

Transactions and agreements

Land and environmental record

Related parties and identifiers

Relationship graph

Timeline and sources

Project timeline

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Parties and identifiers

Reporting portfolio

Sources

Common questions about Watson Cogeneration

How big is Watson Cogeneration?

What kind of plant is Watson Cogeneration?

Where is Watson Cogeneration located?

Who operates Watson Cogeneration?

How much electricity does Watson Cogeneration generate?

Where does Watson Cogeneration connect to the grid?

How does Watson Cogeneration compare to other plants?

Co-located assets