Power Corporation was completed, and it was later uprated to 230 kV. 1961 to date: the Manitoba Hydro era The Manitoba Power Commission and Manitoba Hydro Electric Board merged in 1961 to form Manitoba Hydro. One of the earlier wholesale accounts to be transferred to Manitoba Hydro in 1956 was the village of Emerson, which had been served up to that point by a cross-border tie to the Otter Tail Power system at Noyes. The last of the private mine-owned utility systems at Flin Flon was purchased by Manitoba Hydro in 1973. The early 1970s also marked the installation of tie lines between Manitoba Hydro and utilities in Ontario, Saskatchewan and Minnesota. The interconnection with the American utilities (Otter Tail Power, Northern States Power, and Minkota Power Cooperative) were used to obtain firm power of 90 MW for the winter of 1970; and since that time these interconnections have also been used for export of energy. In the period 1974 to 1976, Manitoba Hydro was still studying nuclear power, but it concluded that all hydraulic resources should be developed first before construction of any nuclear facility. Although a research nuclear reactor existed at the Pinawa AECL research facility, no nuclear generating capacity has ever been constructed in Manitoba. In July 1999, Manitoba Hydro purchased the natural gas distribution company Centra Gas Manitoba. In September 2002, Manitoba Hydro purchased Winnipeg Hydro, which formerly provided electric power in the downtown area of Winnipeg. Nelson River development The water power potential of the Nelson River was described as early as 1911, when over 6 million horsepower of potential generation capacity was identified at 11 sites – at a time when the developed hydropower in the rest of Canada was around 1 million horsepower. Between 1955 and 1960, studies were carried out to determine what resources would be available for future hydraulic generation. The stations at Kelsey, Kettle, Long Spruce and Limestone were built on the lower Nelson River to support both Manitoba load growth and export plans. Limestone, the largest generating station in Manitoba, is located on the Lower Nelson only 90 km from Hudson Bay. Long-term firm power sales contracts were signed with Northern States Power. Control dams have turned Lake Winnipeg, the 12th largest lake in the world, into a 25,000 km2 reservoir for the Nelson River generation system. The great distance between generating sites on the Nelson River and load