Standard Rule Curve to Be Followed this Spring 2022 on Rainy Lake


In accordance with the 2018 Supplementary Order, the Water Levels Committee of the International Rainy-Lake of the Woods Watershed Board has determined that the standard rule curve will be used this spring to guide the operation of the dam at the outlet of Rainy Lake.  Current and forecast conditions, as outlined below, do not support the use of the high flood risk rule curve at this time.

On Thursday, March 3rd the Water Levels Committee hosted a Pre-Spring Engagement Webinar. During this webinar, the Committee’s Engineering Advisors provided a summary of basin conditions and seasonal forecast information. Webinar participants were encouraged to provide their own local knowledge and expertise and share any concerns or additional information for consideration in advance of the freshet season.

In making the rule curve decision the Water Levels Committee considered the following information:

Current Conditions

  • The current drought status for the basin ranges from abnormally dry in portions of Canada to moderate to severe drought in the U.S.
  • Base flow conditions are in the low to normal range for this time of year.
  • To date, overall average winter temperatures are colder than recent years, but warmer than 2014 when significant high-water levels were experienced in the basin.
  • The accumulated snowpack is higher than normal and falls in the 80 to 95 percentile range based on historic records.
  •  According to the AWSSI by the Midwestern Regional Climate Center, the past winter began as average then progressed to the severe range by the middle of February when measured by the accumulated snow and severity of cold weather.

Forecasted Conditions

  • There is currently a La Niña condition. Recent projections of the El Niño–Southern Oscillation (ENSO) in the Pacific Ocean by NOAA show a 77% chance to continue as La Niña in the Northern Hemisphere this spring (March-May 2022) and then 56% transition to ENSO-neutral May-July 2022.
    • Historic data since 1970 show that high water years occur most often when La Niña conditions are present and are less likely during neutral conditions.
  • The current NOAA long-term forecasts of temperature show a 33-40% chance above normal temperatures through March, April, and May.
  • The current NOAA long-term forecast of precipitation shows equal probabilities of low, normal, or above normal precipitation through March, April, and May.
  • Temperatures are expected to fall well below freezing at night during the extended forecast.

Feedback from basin interests

Feedback from basin interests is consistent with the information provided by the Water Levels Committee at the pre-spring engagement.

  • Ice thickness on the lakes this winter is in the normal range. Early snowpack insulated ice from the colder than normal temperature.
  • The snowpack is higher than last year, but significantly less than in 2014 (extreme event).
  • Local observations agreed with snow information presented by the WLC.
  • Water level conditions have been low in recent years and refilling the lake this year would be beneficial from a fisheries perspective.

In the near term, Rainy Lake will be maintained in approximately the middle of its rule curve band. The Water Levels Committee will continue to monitor basin conditions and forecasts as the spring progresses. If conditions change as the year progresses and the risk of flooding changes, the Water Levels Committee may direct the Companies to adjust their target within the standard rule curve for Rainy Lake. For updated information on Water Levels Committee decisions, please visit the Water Level Decisions & Data page of the International Rainy - Lake of the Woods Watershed Board website.


Scott Jutila:                      (651) 290-5631                    

Matt DeWolfe:                (800) 661-5922 ext. 3