The Mica Dam is a hydroelectric dam spanning the Columbia River 135 kilometres north of Revelstoke, British Columbia, Canada. Completed in 1973 under the terms of the 1964 Columbia River Treaty, the Mica powerhouse has a generating capacity of 1,740 MW. The dam is operated by BC Hydro. The Mica Dam, named after the nearby settlement (now drowned under the lake) of Mica Creek and its associated stream in turn named because of the abundance of mica minerals in the area, is one of the largest earthfill dams in the world. The reservoir for the dam is Kinbasket Lake, which was created when the dam was built. Water below the dam flows south directly into Revelstoke Lake, the reservoir for the Revelstoke Dam. The dam's underground powerhouse was the second largest in the world at the time of its construction, and was the first installation of sulphur hexafluoride (SF6) insulated switchgear in North America. It is also the dam farthest up the Columbia River.History
Mica Dam was operational on March 29, 1973. The dam was built to a height of 244 metres (801 ft) above bedrock, near the first location of the village Mica Creek. At the time, the dam was one of three storage dams built by the provincial power company BC Hydro, within the description of the Columbia River Treaty. The dam operated with a 427-square-kilometre (165 sq mi) reservoir containing 15 cubic kilometres (12,000,000 acre·ft) of live storage in McNaughton Lake.
The underground powerhouse, begun in 1973 was built to be 54 metres (177 ft) high, 24 metres (79 ft) wide and 237 metres (778 ft) long. In 1976, the first two electrical generators were commissioned and in 1977 two more were completed bringing the total capacity of the powerhouse to 1740 MW. Another two generators are scheduled to be added and operational in 2014 and in 2015, for a total generating capacity of 2,805 MW.
The Mica powerhouse delivers its power to Nicola Substation via a 500-kilovolt, 570-kilometre (350 mi) transmission line. A second power transmission line for hydroelectric power was built to the Meridian Substation near Port Moody, British Columbia, Canada. In 1980 McNaughton Lake was renamed to Kinbasket Lake. A number of small communities were inundated by the creation of Kinbasket Lake, and comprised a region known as the Big Bend Country, a subregion of the Columbia Country. Among these towns were Mica, Big Bend, and Downie.
Mica Dam was built to provide 7,000,000 acre·ft (8.6 km3) of water storage as outlined in the Columbia River Treaty, plus another 5,000,000 acre·ft (6.2 km3), referred to as "non-Treaty storage". Since 1977 BC Hydro and the Bonneville Power Administration (BPA) have made a series of long and short term agreements for using non-Treaty storage. Negotiations for a new long-term agreement began in 2011. If implemented, it would manage non-Treaty storage until 2024.