Kootenai River at Bonner’s Ferry

Update on Kootenay Lake Water Levels and Conditions
Date

The International Kootenay Lake Board of Control is informing the public that Kootenay Lake inflows peaked on May 18th and have decreased through the late spring and early summer, reaching current, near-historic low flows. On June 25, Kootenay Lake at Nelson dropped below 1743.32 feet (531.36 meters).

Based on the 1938 Order of Approval, the Lake level will be measured at Nelson until August 31st and kept below the 1,743.32-foot mark. The control of Lake level will fluctuate between Corra Linn Dam and the natural constriction at Grohman Narrows (refer to the pink and purple lines of 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 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.
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.

 

 

 

 

 

 

 

 

 

 

 

 

 

During a six weeks period starting at the end of April, temperatures in the Kootenay Lake Basin were well above normal (Figure 2). This caused early and rapid snowmelt in the basin and the freshet peak was observed on May 18 (Green line on Figure 1).

Figure 2. Nelson, BC daily mean temperatures for the past 3 months (black), long-term mean (dashed grey), standard deviations above and below the mean (red, and blue respectively).
Figure 2. Nelson, BC daily mean temperatures for the past 3 months (black), long-term mean (dashed grey), standard deviations above and below the mean (red, and blue respectively)

 

 

 

 

 

 

 

 

 


 

Quick Facts

  • The International Kootenay Lake Board of Control is responsible for overseeing that FortisBC operate Corra Linn Dam, such that Kootenay Lake levels are in compliance with the International Joint Commission 1938 Order of Approval Rule Curve.  
  • The Kootenay Lake Visualization Tool is available to the public to better understand the complexities, competing interests, and physical limitations in the management of Kootenay Lake’s water levels.  
  • Real-time hydrologic conditions for the Kootenay (Kootenai) basin can be found at the Canada Water Office website and the US Geological Survey WaterWatch website, with additional information found on the Fortis BC dam operators website.

 

Contacts

Sonja Michelsen, US Secretary

Martin Suchy, Canadian Secretary

International Kootenay Lake Board of Control