Manitoba to rehabilitate and reconstruct Rivers Dam after 2020 flooding

The Government of Manitoba is taking to steps to rehabilitate and redesign the Rivers Dam on Lake Wahtopanah.

On Tuesday, Transportation and Infrastructure Minister Doyle Piwniuk announced that the province has awarded a design contract to KGS Group Limited.

According to the province, the Rivers Dam controls water levels on Lake Wahtopanah, which serves a provincial park where several cottages are located.

Back in the summer of 2020, heavy rainfall in southwestern Manitoba caused flooding on the Little Saskatchewan River, which affected the Rapid City and Rivers Dams.

Due to this rainfall, the water levels at the Rivers Dam reached record highs, which impacted nearby communities, such as Brandon, Riverdale and Whitehead.

“The peak flow during the 2020 summer event was 12,000 [cubic feet per second], an approximately one in 1,000-year event,” Piwniuk said.

“It was greater than two times the previous peak outflow of 4,500 CFS.”

He noted the concern over the aging spillway's ability to pass the record water flows led to an evacuation of residents downstream from the dam.

“Approximately 83 people moved from their homes in the flooded zone areas, which included the municipality of Riverdale, the RM of Whitehead and the city of Brandon,” the minister said.

Interim repair work on the spillway was finished in the winter of 2021, and the dam has been performing well. The goal of the redesign will be to bring the dam to current standards so it can operate during extreme flood events.

KGS is working on the preliminary design for several permanent options for the repair work.

The province noted the final design will follow Canadian Dam Association Guidelines. The Manitoba government will work with the municipalities of Riverdale and Oakview, local residents, and landowners through two rounds of stakeholder and public engagement efforts.

Construction on the dam is set to begin in 2023 and is expected to take about three years.