August 16, 2021: Low Kootenay Lake water levels
The current level of Kootenay Lake is at its lowest level for mid-August since Water Survey of Canada (WSC) records began in 1928. The lake level on August 15 measured at Queens Bay was 1,742.37 feet (531.07 m). This is 1.89 feet (0.58 m) lower than the mean historical water level (1928 to 2020 period of record) on this date (Figure 1: Kootenay lake water levels and IJC Rule Curve). The low lake level is in response to very dry conditions and above normal temperatures in the Kootenay(ai) River basin over the past several months (Figure 2: Cranbrook, BC Temperatures for past 3 months). Corra Linn Dam is being operated in a manner that is compliant with the IJC 1938 Order of Approval, which requires the lake level to be held below a maximum level of 1,743.32 feet (531.36 m) as measured by the gauge at Nelson until August 31. The current lake level at Nelson is 1,741.90 feet (530.93 m) (Figure 1). Starting September 1, the Rule Curve for Kootenay Lake level will increase to 1,745.32 feet and switches back to the Queens Bay gauge for compliance measurements.
Figure 1: Kootenay lake water levels and IJC Rule Curve
Figure 2: Cranbrook, BC Temperatures for past 3 months