Regulation plan launched for Rainy Lake


The International Rainy-Lake of the Woods Watershed Board Water Levels Committee (WLC) has established an initial spring regulation plan for Rainy and Namakan Lakes. The plan, launched on March 10, is in accordance with a new temporary supplementary Order, and takes into account the previous high flood risk and the standard rule curves. A rule curve provides an ideal upper and lower limit of water depths, to allow a broad range of water uses, from recreation to industry needs. It guides the International Joint Commission’s dam operation, as it attempts to maintain a standardized and predictable level of water in Rainy and Namakan Lakes.

The temporary supplementary order, which was launched by the International Joint Commission on March 3, will be in effect until July 15, 2023. It drops the lower limit of the curve, and guides the Commission to maintain levels in the lower third of the curve. This temporary order provide flexibility to direct dam operations as spring develops without having to employ a different rule curve.

In accordance with the WLC spring regulation plan, the March 31st target water levels for both Rainy and Namakan Lakes will be the lower third of their respective rule curve bands. The WLC will monitor conditions over the coming weeks and provide further direction for lake level regulation prior to the end of March 2023.

The International Joint Commission has instated a Temporary Supplementary Order, which will direct them to drop water levels lower than the traditional curve. Stakeholder feedback showed a desire for lower lake levels, to allow for dock and property repairs after last year’s historic flooding. – Supplied image

The March 31st targets were established based on an evaluation of current conditions including the following factors:

  • Above-normal snow water equivalent in the headwaters, with lesser amounts to the west and closer to normal near Rainy River.
  • Groundwater supplies in the normal/slightly above normal range for the tributaries upstream of Namakan and Rainy Lakes.
  • The potential for above-normal spring flows for the US tributaries in the Rainy River Basin identified by the National Weather Service- North Central River Forecast Center.
  • Warmer than normal winter temperatures to date with lower frost depth below the ground surface.

An information public session was held on February 27, 2023 which provided a summary of basin conditions and seasonal forecast information. Feedback from landowners and stakeholders at that meeting also expressed an interest in lower than average lake levels this spring, to allow for dock and property repairs left over from last year. A follow up public webinar will be hosted by the WLC in early April to provide an update on conditions as part of the spring regulation plan.