High flood risk rule curve adopted

Press Release

The Water Levels Committee of the International Rainy-Lake of the Woods Watershed Board will use the high flood risk rule curve on Rainy Lake and directed the dam operators to begin targeting the mid-band of the high flood risk rule curve.
The high flood risk rule curve calls for lower-than-normal water levels on Rainy Lake during the spring period to provide for more water storage when a flood risk is identified.
Last Monday (March 4), the Water Levels Committee hosted its first pre-spring engagement webinar.
During this webinar, the engineering advisors provided a summary of basin conditions and seasonal forecast information to the Water Levels Committee and invited representatives of basin interests.
Webinar participants were encouraged to provide their own local knowledge and expertise, as well as share any concerns or additional information for consideration in advance of the freshet season.
The Water Levels Committee made its decision based on the following information:
Current conditions
­•baseflow conditions are higher-than-normal for this time of year (similar to 2018 and higher than 2014);
•to date, overall average winter temperatures are normal (higher than 2018 and much higher than 2014);
•the accumulated snowpack is higher than normal (higher than 2018 and close to 2014 conditions); and
•the overall winter severity is average (similar to 2018 and much lower than 2014).
Forecasted conditions
•current projections of the El Niño-Southern Oscillation (ENSO) Forecast Probability show a zero percent chance of a La Niña condition, a 26 percent chance of a neutral condition, and a 74 percent chance of an El Niño condition (historic data since 1970 show that high water years occur most often when La Niña conditions are present);
•current long-term forecasts of temperature show equal probabilities of low, normal, or high temperature through April, May, and June;
•the current U.S. National Oceanic and Atmospheric Administration (NOAA) long-term forecast of precipitation shows equal probabilities of low, normal, or high precipitation through April, May, and June;
•on March 8, the NOAA seven-day quantitative precipitation forecast showed an additional 0.75-inch to 1.5-inch of precipitation forecasted through March 15; and
•the current Environment and Climate Change Canada (ECCC) long-term forecast of precipitation shows a 40 percent chance of above-normal precipitation through April, May, and June.
Fisheries representatives cautioned that higher water levels in spring generally are better for fish spawning (especially northern pike) and that too many consecutive years with low water should be avoided.
The Rainy Lake Property Owners’ Association, meanwhile, stated its support for the use of the high flood risk rule curve due to concerns over potential flooding.
Other community members stated they would like to learn more about the risks associated the decision to target the high flood risk rule curve or remain within the standard curve.
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 decreases, the Water Levels Committee may direct the companies to return to following the standard rule curve for Rainy Lake.
The International Joint Commission’s 2018 Supplementary Order states that the determination to follow the high flood risk rule curve should be made by the Water Levels Committee no later than March 10 of each year.
The International Rainy-Lake of the Woods Watershed Board’s Water Levels Committee will present information on conditions in the basin, as well as the current spring forecasts, at a public meeting today (March 12) at 7 p.m. at the Rainy River Community College (Theater/Auditorium) in International Falls.
All are welcome to attend.
For further information on this meeting, visit WLC-media@ottawa.ijc.org

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