| Abstract/Description or Keywords |
2011 Annual Report: This Annual Report covers the operations of the Corra Linn Dam by FortisBC (the Applicant) and the associated effects on the water level of Kootenay Lake. FortisBC operates Corra Linn Dam on the Kootenay River approximately 22 kilometres upstream from its confluence with the Columbia River, and downstream from the West Arm of Kootenay Lake. Fortis BC controls discharge through and around Corra Linn Dam in accordance with requirements of the Order of the International Joint Commission dated November 11, 1938. [FortisBC co-operates with BC Hydro, which also manages a lake level control structure—the Kootenay Canal Plant—at the lake’s outlet.] Kootenay Lake 2011 Summary: Throughout 2011, FortisBC operated Corra Linn Dam in a manner consistent with that prescribed by the 1938 Kootenay Lake Order. The minimum instantaneous water level was observed at 20:00 PST on April 23rd at elevation 530.494 metres (1740.47 feet). Lake levels did not lower to the elevation of 1739.32 feet specified for April 1 in condition 6 of the 1938 Order because of high inflow conditions resulting primarily from the operation of upstream facilities during March. During this time, FortisBC lowered the level of the Corra Linn Dam forebay sufficiently to move the control of outflow from the lake upstream from the Dam to Grohman Narrows, maximizing the lake’s discharge. Impacts of reduced gravity drainage of fields and associated higher pumping/drainage costs and difficulty in conducting annual repairs around the lakeshore were reported to the Kootenay Lake Board of Control. The Board and the Applicant jointly determined the date of the commencement of the spring rise as May 3, 2011. The maximum instantaneous water level for the lake at Queens Bay was subsequently observed at 05:00 PST on June 16th at elevation 533.917 metres1 (1751.70 feet). The Board received a comment appreciative of the flood control effort, noting that the water level came within approximately nine inches of flooding their house. One negative impact of the high water level that was reported to the Board was increased costs of mosquito control attributed to increased flooding of wetlands. Kootenay Lake discharged 29.3 cubic kilometres (23.7 million acrefeet) of water in 2011, with an average flow of 929 cubic metres per second (32,800 cubic feet per second). |
