1906: The Ontario Legislature passes the Power Commission Act and creates the Hydro-Electric Power Commission principally to build transmissions lines to supply municipal utilities with power generated at Niagara Falls by existing private companies. Adam Beck, a Minister without Portfolio, is named Chairman of the HEPC.
1907: Toronto City Council approves the development and public control of hydro-electric power, thanks to the leadership and commitment of Adam Beck's ally William Peyton Hubbard. Together they make a formidable team, Beck fighting for public ownership province-wide, and Hubbard taking the lead at the municipal level. The son of a freed slave from Virginia, Hubbard was first elected to Toronto City Council in 1894.
1908: The HEPC signs contracts to purchase power at Niagara Falls and transmit it over its own lines, yet to be constructed, to municipal electric distribution utilities in Toronto and 13 other southwestern Ontario municipalities.
1910: The HEPC's first 110,000-volt bulk electric power lines supply hydro to municipalities in southwestern Ontario. A special ceremony at Berlin (now Kitchener), Ontario, marks the initial delivery of power by the Commission. Municipal electrification efforts expand rapidly to a highpoint of 360 municipal electric utilities in the 1960s.
1912: The famous "Beck Circus" tours the countryside showcasing the latest electric appliance and farm equipment. The HEPC institutes electrical inspection throughout the province.
1914: Adam Beck is knighted by King George V for services rendered to the Commonwealth of Canada. The HEPC constructs its first owned generating station at Wasdell Falls on the Severn River.
Early 1920s: The HEPC becomes an electric distributor itself, not just a transmitter to municipal utilities, when it is mandated to electrify rural areas directly.
1922: The first unit of the HEPC's Queenston Chippawa hydro-electric development on the Niagara River goes into service. When complete in 1925, it is the largest generating station in the world. The station is later named Sir Adam Beck 1 in 1950, marking the 25th anniversary of Beck's death.
1922: The HEPC buys out the generation and transmission assets of the largest of the remaining private power companies, the Electrical Development Corporation.
1926: The HEPC enters into a long-term contract to obtain power from the Gatineau Power Company and other power companies in Quebec to meet growing demand. Jurisdictional complications impede the development the St. Lawrence and Ottawa rivers, the preferred sources of power. The contracts become controversial in the Great Depression when there is an overcapacity in the system.
1939: The HEPC must redouble efforts to produce power for the war. The Quebec contracts are redeemed as an important source of power for war production.
1944: The HEPC's southern Ontario distribution service is amalgamated into one rural power division. The change introduces a common rate for each class of service except industrial customers. Separate systems remain for northern Ontario.
Late '40s and '50s: the HEPC develops the hydro-electric potential of the St. Lawrence in conjunction with American power authorities during the development of the St. Lawrence Seaway. The HEPC also develops stations on the upper Ottawa River and Quebec utilities receive rights to the lower Ottawa River.
1949-Mid-1950s: The HEPC integrates all its power stations and transmission systems into one network for operational efficiency and flexibility. In doing so, the HEPC simultaneously standardizes the frequency of its electrical delivery system at 60 cycles by converting the 25 cycle portions of the province, ensuring compatibility with neighboring power systems and overcoming the major obstacle to expansion of its network and systems. This frequency standardization program is one of the world's largest door-to-door engineering projects at the time, with HEPC changing the motors of over 7 million appliances.
1951-1953: Hydro-electric development is supplemented for peaking purposes by construction of thermal, coal fired power stations in Toronto (R.L. Hearn) and Windsor (J.C. Keith).
1954-1958: The 1328-megawatt Sir Adam Beck 2 plant is built on the Niagara Gorge adjoining Sir Adam Beck 1.
1958: The 912-Megawatt R.H. Saunders plant in Cornwall, Ontario is declared in service by Queen Elizabeth and American Vice-President Richard Nixon. The plant is one half of a huge power station extending across the St. Lawrence River to the United States. The other half is the Franklin D. Roosevelt power station, owned and operated by the New York Power Authority.
1960: Construction of Canada's first extra-high-voltage (500,000 Volts) transmission line begins, bringing power from northern Ontario to demand in southern Ontario. This transmission line comes into service in 1967.
1962: The HEPC and Atomic Energy of Canada Limited operate the experimental 25-megawatt Nuclear Power Demonstration plant at Rolphton on the Ottawa River.
1968: The 200-megawatt Douglas Point Nuclear Generating Station comes into service.
1970: All of Ontario's power systems are joined into one synchronized, province-wide grid, with the exception of remote communities.
1971: The first unit of the Pickering Nuclear Generating Station comes into service. When complete, it has eight 540-megawatt generating units.
1974: The Power Corporation Act replaces the Power Commission Act and the Hydro-Electric Power Commission is recreated as Ontario Hydro (as it had been known informally), a crown corporation governed by a board of directors. The new corporation is subject to scrutiny but not regulation by the Ontario Energy Board.
1977: The first unit of the Bruce Nuclear Generating Station comes into service. When complete, it has eight reactors each about one and a half times the size of Pickering reactors.
1989: The first unit of the Darlington Nuclear Generating Station comes into service. When complete, it has four reactors about the size of the reactors at Bruce.
1989: Ontario Hydro initiates a 25-year demand supply planning exercise.
1992: Ontario Hydro is facing a downturn in the economy and shrinking demand. Eventually the ambitious demand supply plan is dropped.
1995: The Ontario Government establishes the Macdonald Committee as an Advisory Committee on Electricity Competition to provide recommendations on the restructuring of Ontario's electric industry.
1996: The Macdonald Committee recommends sweeping changes including an open market in electricity.
1997: The Ontario Government issues a White Paper entitled, "Direction for Change: Charting a Course for Competitive Electricity and Jobs in Ontario," which sets a course for anticipated legislation for restructuring Ontario's electric industry.
Winter 1998: An unprecedented ice storm hits eastern Ontario and damages 40 percent of Ontario Hydro's distribution systems, throwing 150,000 customers into darkness and freezing temperatures for as long as three weeks. The high-voltage transmission system to the major urban centres remains largely intact. Undaunted by treacherous icy conditions, nearly 2200 employees from Ontario Hydro, other utilities and contractors work 16-hour shifts, 7 days a week to replace 10,750 wood poles, 1,800 pole-top transformers, and 2,800 kilometres of wire conductor.
October 1998: The Energy Competition Act authorizes the restructuring of Ontario Hydro and the eventual opening of wholesale and retail electricity markets in Ontario.
April 1, 1999: In accordance with the Energy Competition Act, Ontario Hydro is restructured principally into three separate companies: Ontario Power Generation, The Ontario Hydro Services Company and the Independent Market Operator. The legislation transforms the company from a government corporation with its own statute into a share ownership company under Ontario's Business Corporations Act, like any other business.
1996 to 1999: The North American Electric Reliability Council requires all utilities to take extraordinary measures to ensure that the electric power system withstands the automation issues posed by the infamous "Year 2000". Ontario Hydro is a leader of the industry and is the first North American utility to conduct a live test of Year 2000 readiness.
1999-2002: The Ontario Hydro Services Company becomes an industry leader in working with the Independent Market Operator and the Ontario Energy Board to facilitate the creation of wholesale and retail electricity markets in Ontario.
May 1, 2000: Ontario Hydro Services Company is re-branded as Hydro One Inc.. Hydro One is launched as a corporate holding company with five subsidiaries: Hydro One Networks Inc., Hydro One Remote Communities Inc., Hydro One Markets Inc., Hydro One Telecom Inc., Ontario Hydro Energy Inc.