2025 Kootenay Lake Spring Rise Declaration
Date

The International Kootenay Lake Board of Control, after consultation with FortisBC, the operator of the Corra Linn Dam, has determined that “the commencement of the spring rise,” for purposes defined in the 1938 International Joint Commission Order that sets the maximum level of Kootenay Lake, occured at 00:00 PDT on April 18, 2025. 

The maximum allowable level of Kootenay Lake will now be calculated based on the lowering formula defined in the Order until the lake returns to an elevation of 1,743.32 feet as measured at Nelson, British Columbia, after the flow is no longer affected by snowmelt runoff (sometime in the summer). Reaching this threshold will mark the end of the freshet period for the Kootenay Lake basin. Information on the IJC 1938 Order of Approval for Kootenay Lake can be found here; the lowering formula is referenced on page 4 in item 2, part 6.

The spring rise declaration comes at a comparable time to the 2024 spring rise. There have been sustained higher temperatures at higher elevations, and increasing temperatures are expected again in the medium-term and long-term forecast. The local snowpack at medium and higher elevations is showing signs of melting, and a recent increase in Kootenay Lake tributary flows and Kootenay River inflow has been observed.

Prior to the declaration, the level of Kootenay Lake at Queens Bay, British Columbia, was 1739.75 feet (530.28 meters) on April 17, 0:00 PT. Kootenay Lake inflow was 20,600 cubic feet per second (583.3 cubic meters per second) and is forecast to continue increasing for the next month. For reference, Kootenay Lake at Queens Bay reached its minimum daily average elevation of 1,739.62 feet (530.24 meters) for the year on April 7, 2025. From March 28 to April 18, lake level at Queens Bay remained above the allowable rule curve; however, lake outflow during this time was constrained by Grohman Narrows (not Corra Linn Dam) so FortisBC was in compliance with the IJC Order (Figure 1).  

A graph showing the rule curve of Kootenay Lake overlaid by lake levels measured at different points.
Figure 1. 2025 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 2025 (red).

 

Please monitor the board website for further hydrologic updates or sign up for notifications. 

A follow-up news release detailing observed freshet conditions will be posted in coming months once the freshet peak has been recorded. Real-time Kootenay Lake levels can be found at the FortisBC website.  

Quick Facts

  • The International Kootenay Lake Board of Control oversees the operation of Corra Linn Dam to manage water levels in Kootenay Lake; Fortis BC is the dam’s owner/operator.
  • This year’s board and public meetings are scheduled for Wednesday May 7, 2025. The public meeting will be held at 6:30-8pm PDT in Nelson, British Columbia with a virtual option. Virtual registration can be found here.
  • The web-based Kootenay Lake Visualization tool is available for the public to investigate Kootenay Lake conditions in dry, normal and wet years. The link is here.
  • To contact the board by email, click “Contact” under “Contact Us” at top right of the board website.
  • Stay in touch and subscribe to receive email news updates from the Kootenay board.

Contacts

Sonja Michelsen, U.S. Secretary

Martin Suchy, Canadian Secretary

International Kootenay Lake Board of Control