Hydro One
Corporate brand
UnclaimedOntario's largest electricity transmission and distribution utility, serving customers across the Canadian province of Ontario.
Last updated August 21, 2026
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Overview
Hydro One Limited is an electricity transmission and distribution company serving the province of Ontario, Canada. Its corporate predecessor was created during the restructuring of Ontario Hydro in 1999, when the former provincial electricity Crown corporation was divided into separate organizations for generation, transmission and distribution, market administration, electrical safety, and financial obligations. Hydro One therefore has a modern corporate identity dating from the late 1990s, but its operating history reaches back to the creation of the Hydro-Electric Power Commission of Ontario in 1906. The company is primarily an infrastructure operator rather than an electricity generator. Through Hydro One Networks and related subsidiaries, it operates approximately 98% of Ontario's high-voltage transmission network and maintains a large distribution system serving roughly 1.4 million customers, particularly in rural and smaller-community service territories. Its transmission network uses 500-kilovolt, 230-kilovolt, and 115-kilovolt alternating-current lines and connects major generators, municipal utilities, industrial customers, and neighbouring provincial and American power systems. Hydro One's distribution facilities generally operate at 50 kilovolts or below and deliver electricity to homes, farms, businesses, and communities. Hydro One's network does not represent the whole Ontario electricity value chain. Generation is carried out by organizations including Ontario Power Generation, Bruce Power, and independent producers using nuclear, hydroelectric, natural-gas, wind, and solar facilities. The Independent Electricity System Operator manages the province's electricity market and system operations. Hydro One's role is to move electricity safely and reliably between generators, large users, municipal utilities, and end customers, while expanding or reinforcing infrastructure when demand, reliability requirements, or new generation projects require it. The company grew substantially after the 1999 restructuring, acquiring 88 municipal electricity utilities by 2001 and consolidating much of Ontario's fragmented distribution sector. It later acquired Norfolk Power's assets and customers, while its separate Brampton distribution subsidiary was sold to Alectra Utilities in 2017. Hydro One became publicly traded on the Toronto Stock Exchange in 2015, as the Government of Ontario began a staged sale of shares. The offering and subsequent privatization were politically contentious, particularly because of concerns about infrastructure condition, electricity affordability, executive compensation, and the appropriate public role in an essential utility. Hydro One's attempted acquisition of Avista Corporation, a United States energy company, became another major turning point. Announced in 2017 for approximately C$6.7 billion, the transaction was blocked by the Washington Utilities and Transportation Commission in 2018 after regulators questioned whether Hydro One could operate independently from Ontario's government. Hydro One paid Avista a reported C$103 million termination fee. The episode reinforced the importance of regulatory independence and political governance for the company. Today, Hydro One remains a publicly listed Ontario utility with a regulated infrastructure business. Its strategic priorities include grid reliability, transmission expansion, rural service, connection of new generation and load, storm restoration, system modernization, and investment in long-lived electricity assets. In March 2025, Hydro One Networks completed the acquisition of a 48% interest in the East-West Tie Limited Partnership, which owns a 450-kilometre transmission line between Wawa and Thunder Bay. The company continues to operate within Ontario's regulated electricity framework and is not a global consumer brand, but its network is central to the province's electricity system.
History
Hydro One's history is rooted in Ontario's public-power movement. In 1906, the provincial government established the Hydro-Electric Power Commission of Ontario under the Power Commission Act. Led initially by Adam Beck, the commission was intended to develop a publicly controlled transmission system that could move electricity generated at Niagara Falls and elsewhere to municipal utilities. The commission built its first generating station on the Severn River in 1914 and expanded from a transmission intermediary into a broader electricity supplier during the 1920s. The commission's Niagara development grew rapidly. The first unit of the Chippawa hydroelectric project began operating in 1922, and the completed project was described at the time as the world's largest generating station. The organization also acquired the generation and transmission assets of the Electrical Development Corporation, the last major private electricity company in Ontario. Long-term power contracts with Quebec's Gatineau Power Company helped meet rising demand but later became controversial during the Great Depression, when the system faced overcapacity. After the Second World War, Ontario expanded hydroelectric development along the St. Lawrence River and integrated previously separate power stations and transmission assets into a more coordinated network. Coal-fired thermal plants were added during the 1950s, while construction began on Canada's first 500-kilovolt transmission lines to move electricity from northern generating resources toward southern Ontario. By the beginning of the 1970s, the province's major electricity systems had been linked into a province-wide grid. In 1974, the Power Corporation Act reorganized the commission as the Crown corporation commonly known as Ontario Hydro. Ontario's electricity sector was fundamentally reorganized during the late 1990s. The Progressive Conservative government passed the Energy Competition Act in 1998, establishing the framework for a competitive electricity market and separating generation, transmission and distribution, system-market administration, electrical safety, and legacy financial obligations. On April 1, 1999, Ontario Hydro's operations were divided among Ontario Power Generation, the Ontario Hydro Services Company, the Independent Electricity Market Operator, the Electrical Safety Authority, and the Ontario Electricity Financial Corporation. The Ontario Hydro Services Company became the foundation of Hydro One and was renamed Hydro One Incorporated in May 2000. Hydro One was organized as a holding company with subsidiaries including Hydro One Networks, Hydro One Remote Communities, Hydro One Telecom, and Hydro One Brampton. Between 1998 and 2000, it acquired 88 municipal electricity utilities, accelerating the consolidation of Ontario's distribution sector. Plans for an initial public offering announced in 2001 were challenged in court and did not proceed at that time. An electricity market nevertheless opened in 2002, while political disputes over prices led to a temporary freeze for residential and small-business customers. The company later expanded and rationalized its distribution footprint. Hydro One acquired the assets and customers of Norfolk Power in 2014. Hydro One Brampton, which had operated as a distinct local distribution business, was sold to Alectra Utilities in February 2017. The Government of Ontario launched Hydro One's public offering in 2015 and subsequently sold additional shares, retaining a significant public interest while transforming the company into a Toronto Stock Exchange-listed corporation. Privatization generated continuing criticism. A 2015 Auditor General report highlighted aging infrastructure, rising outage concerns, and substantial estimated repair needs. Executive compensation also became a prominent political issue. In 2018, following the Ontario election, CEO Mayo Schmidt retired and the company's existing board resigned during a government-supported governance change. Paul Dobson served as interim chief executive while a replacement process was conducted. Hydro One's proposed 2017 purchase of Avista represented an attempt to expand beyond Ontario. The transaction was valued at approximately C$6.7 billion but was rejected in December 2018 by the Washington Utilities and Transportation Commission. The regulator cited concerns about Hydro One's independence from the Ontario government. The unsuccessful transaction resulted in a reported C$103 million termination payment to Avista. Hydro One remains focused on regulated transmission and distribution. Its system includes roughly 29,000 kilometres of high-voltage transmission lines and approximately 123,000 kilometres of lower-voltage distribution infrastructure, although customer and network figures vary by reporting period and definition. The company interconnects with neighbouring systems including Manitoba Hydro, Hydro-Québec, Minnesota Power, DTE Energy and ITC, National Grid, and the New York Power Authority. In March 2025, Hydro One Networks completed the acquisition of a 48% interest in the East-West Tie Limited Partnership, adding an interest in a 450-kilometre transmission line linking Wawa and Thunder Bay.
- 2025
East-West Tie interest acquired
[2]Hydro One Networks completed the acquisition of a 48% interest in the partnership owning the East-West Tie transmission line.
- 2018
Avista acquisition blocked
[1]A Washington regulator rejected Hydro One's proposed acquisition of Avista, ending the company's major U.S. expansion attempt.
- 2017
Hydro One Brampton sold to Alectra Utilities
[1]The separately operated Brampton distribution utility was acquired by Alectra Utilities.
- 2015
Hydro One completes initial public offering
[1]The company became publicly traded on the Toronto Stock Exchange as Ontario began broadening ownership.
- 2014
Norfolk Power assets acquired
[1]Hydro One expanded its distribution operations by acquiring Norfolk Power's assets and customers.
- 2001
Municipal utility consolidation reaches 88 acquisitions
[1]Hydro One had acquired 88 municipal electricity utilities as Ontario's distribution sector consolidated.
- 2000
Ontario Hydro Services Company renamed Hydro One
[1]The distribution and transmission successor was renamed Hydro One Incorporated and organized as a holding company.
- 1999
Ontario Hydro is divided into successor organizations
[1]Generation, transmission and distribution, market operations, electrical safety, and financial responsibilities were separated.
- 1974
Ontario Hydro becomes a Crown corporation
[1]The Power Corporation Act reorganized the provincial electricity system under the Ontario Hydro name.
- 1922
Chippawa hydroelectric development begins service
[1]The first unit of the Niagara River development entered service, supporting Ontario's expanding integrated power system.
Products and positioning
A regulated, publicly traded electricity infrastructure operator focused on the reliability and expansion of Ontario's transmission and distribution grid, with a particularly extensive presence in rural and smaller-community markets.
Transmission infrastructure
Electricity transmission
Hydro One operates most of Ontario's high-voltage transmission system, moving electricity from generating facilities to large industrial customers, municipal utilities, and distribution networks. Its transmission assets include lines operating at 500 kilovolts, 230 kilovolts, and 115 kilovolts, together with substations and interconnections to neighbouring power systems.
Electric utility service
Electricity distribution
Hydro One distributes electricity to approximately 1.4 million customers, with a particularly large presence in rural Ontario and smaller communities. The distribution business maintains lower-voltage lines, poles, substations, meters, and related equipment and is responsible for service reliability, connections, outage response, and restoration.
Utility interconnection
Grid connection services
The company connects generators, industrial facilities, municipal utilities, and other electricity users to its transmission and distribution networks. Connection work can involve technical studies, reinforcement of lines and equipment, protection systems, and coordination with Ontario's electricity system operator.
Specialized utility service
Remote and rural electricity infrastructure
Through its service territory and historical subsidiary structure, Hydro One has supported electricity delivery in remote and sparsely populated areas of Ontario. These operations require long distribution circuits, specialized maintenance, and storm-response capabilities across geographically extensive territories.
Controversies
2018
Executive compensation and governance controversy
CEO Mayo Schmidt's reported compensation became a central issue in the 2018 Ontario election. After the election, Schmidt retired and the company's board resigned during a government-supported governance overhaul.
2015
Privatization and infrastructure-condition controversy
The Auditor General of Ontario questioned the timing and implications of Hydro One's sale, reporting concerns about aging equipment, increasing outages, and significant repair requirements. The issue became part of the broader debate over whether a core electricity utility should remain publicly controlled.
Marketing campaigns
- 2015Hydro One broadening of ownership
Ontario · Canada
The Government of Ontario promoted the initial public offering and subsequent share sales as a broadening of ownership intended to place a majority of the company in private hands while preserving public participation.
Outcome. Hydro One became a publicly traded company, although the sales generated substantial political and public debate.
Brand decisions
2025
Acquire East-West Tie partnership interestM&ABackground
Hydro One sought to expand its Ontario transmission infrastructure portfolio and strengthen its role in the province's northwestern transmission system.
Action taken
Hydro One Networks completed the acquisition of a 48% interest in the East-West Tie Limited Partnership, which owns the 450-kilometre East-West Tie line.
Aftermath
Hydro One became a significant ownership participant in the transmission corridor connecting Wawa and Thunder Bay.
Acquisition consideration. C$261 million (2025)
2017
Agree to acquire AvistaM&ABackground
Hydro One pursued geographic expansion beyond Ontario through the acquisition of U.S. energy company Avista.
Action taken
Hydro One agreed to purchase Avista for approximately C$6.7 billion in cash.
Aftermath
The Washington Utilities and Transportation Commission blocked the transaction in 2018, and Hydro One paid Avista a reported C$103 million termination fee.
Proposed acquisition value. C$6.7 billion proposed transaction; C$103 million reported termination fee (2017-2018)
2015
Launch public offeringStrategyBackground
Ontario sought to broaden ownership of Hydro One after years of debate over the structure of the provincial electricity sector.
Action taken
The company listed shares on the Toronto Stock Exchange and the provincial government began selling portions of its holding.
Aftermath
Hydro One became a public company, while the transaction attracted criticism concerning valuation, infrastructure investment, public control, and electricity affordability.
Recent events
Reported
Hydro One links credit-line pricing to sustainability targets[4]
Hydro One completed amendments to its syndicated lines of credit, adding pricing adjustments that can raise or lower its funding costs based on performance against sustainability measures.
Reported
Hydro One completes acquisition of PDI business assets[5]
Hydro One Limited, through its wholly-owned subsidiary Hydro One Inc., completed the legal acquisition of the business assets of Peterborough Distribution Inc.
Reported
Hydro One appoints Stacey Mowbray to its board[6]
Hydro One announced that Stacey Mowbray was appointed to its Board of Directors. She fills the vacancy created when Anne Giardini did not stand for re-election at the company's 2020 annual general meeting.
Sources6 sources
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