Kootenay Lake Level has Crested, Now Decreasing 


Following above-normal temperatures in May and below-average snowpacks in the Kootenay basin, inflows to Kootenay Lake peaked on May 18. 

The peak was 84,400 cubic feet per second (cfs) or 2,390 cubic meters per second (cms).  As of June 5, lake inflows were at 30,600 cfs (866.5 cms) and are trending downward.  

With the decrease of inflows, the Kootenay Lake level as measured at Queens Bay crested on May 23 at an elevation of 1748.52 feet (532.95 m).  

During the freshet period, the natural constriction below Kootenay River at Grohman Narrows has been controlling the lake outflow, visualized by the purple line at the bottom of Figure 1.  

kootenay crest figure 1


Figure 1: Kootenay Lake levels at Queens Bay (green) and Nelson (orange), lake outflow control by Corra Linn (pink) or Grohman Narrows (purple), and the International Joint Commission 1938 Order of Approval Rule Curve for 2022 (red). Credit: FortisBC (data) and Environment and Climate Change Canada (plot), 2023

Water level decline on Kootenay Lake will depend on the rate of decreasing inflows and the potential for weather events that could bring precipitation to the basin. This may create additional peaks in flows and lake levels. However, any additional peaks are expected to be minimal. Due to the snow pillows being near historical minimums as of June 5 (Figure 2), snowmelt is not expected to significantly contribute to future peaks.  

kootenay crest figure 2

Figure 2: 2023 data from the Redfish Creek and Moyie Mountain snow pillow station. Orange lines illustrate the Snow Water Equivalent (SWE) for the current year. Credit: BC River Forecast Center (data) and Environment and Climate Change Canada (plot), 2023 

Corra Linn Dam will be operated to draw the lake level down in a manner compliant with the International Joint Commission 1938 Order of Approval until the lake level at Nelson reaches 1,743.32 feet (531.36 m). Then, the lake will be held below the maximum allowable lake level until September 1. As of June 5, the Nelson gauge is at 1,745.69 feet (532.09 m).