first version of the act was effective March 31, 1961 and it has been revised since that date. Notably, the Act now carries a provision prohibiting privatization of Manitoba Hydro without a public referendum. Since 1970, a Minister responsible for the Manitoba Hydro Act has sat on Executive Council of Manitoba. This position is not a full departmental portfolio in the Manitoba executive council, and it is generally held by ministers who also hold other cabinet responsibilities. Generating stations Generating station total ratings are approximate. Water flow conditions and station service load may account for some of the difference between rated station output and total unit nameplate rating. In a typical year the hydroelectric plants produce more than ninety-five percent of the energy sold. Transmission AC system Manitoba Hydro operates an extensive network of more than 9000 km of ac transmission lines. Transmission voltages in use include: 66 kV 115 kV 138 kV 230 kV 500 kV Distribution voltages include 4160 V especially in urban Winnipeg, 12.47 kV and 25 kV, usually on overhead conductors but often in buried cables. Total length of distribution lines is over 80,000 km. Transmission lines built in Manitoba must withstand a wide temperature range, ice, and occasional high winds. In 1997, a tornado blew down 19 transmission towers of the HVDC system north of Winnipeg, reducing transmission capacity from the North to a small fraction of system capacity. During the several days required for utility employees to repair this line, power was imported from the United States over the 500 kV interconnection. As a consequence, though some major industrial customers were requested to curtail energy use, disruption for most customers remained small. DC system A large portion of the energy generated on the Nelson river is transmitted south on the HVDC Nelson River Bipole system. The two transmission lines BIPOLE I and BIPOLE II, each nearly 900 km long, operate at ± 450 kV and ± 500 kV DC, with converter stations at Gillam and Sundance, and the inverter station, Dorsey, near Rosser. The combined capacity of the two HVDC lines is 3420 MW, or about 68% of the total generation capacity in the province. A third HVDC line, BIPOLE III was completed July 4, 2018. At a cost of $4.7B, it carries 2000 MW capacity over 3076 towers and 1384 km. Two new converter stations were built at Keewatinohk on the Nelson River