Front Street in Fort Frances flooded in June 2022. Image: Randy Thoms

The Namakan Chain of Lakes and Rainy Lake reached some of the highest water levels on record last year.

Lake levels did not recede until July.

The International Rainy-Lake of the Woods Watershed Board’s water levels committee toured the area last summer and has filed its final report to the International Joint Commission.

The report looks at the conditions that led to the flooding and the response taken by the watershed board and its water levels committee.

Record precipitation in April and May was a contributing factor.

A total of 257 mm, or 10.1 inches, fell during the two months, more than twice the average for either month.

“The intensity and longevity of the spring precipitation caused flows in the tributaries of the Rainy River watershed to remain at high or close to peak levels from late April to mid-June,” the report states. “The Vermilion River set a new peak flow record, and many other tributaries ranked second or third for all-time high flows. The long duration of these high flows fed the inflows to the lakes and ultimately became the driving force behind the flooding.”

The committee took a lot of criticism.

In a forecast prior to the April storms, it did not see the area being at high risk of flooding, and lake levels were kept within the normal rule curve that identifies maximum and minimum levels because conditions at that time did support a change.

The committee says computer simulation modelling conducted later showed that operating under a rule curve recognizing a high flood risk would have done little to reduce the flooding.

It says the peak level on Namakan Lake would have been one centimetre less, with the lake level dropping below the All-Gates Open level at the dam one day sooner.

Rainy Lake would have peaked at four centimetres lower and fallen below the All-Gates Open two days sooner.

The water levels committee did take action following the flood to improve communications and forecasting abilities.

This included asking the International Joint Commission for a since rule curve to be implemented during the spring, eliminating the choice of a regular or high flood risk rule curve.

You can read the full report by clicking the image below.