FWP News: PUBLIC CAUTIONED TO STAY OUT OF MISSOURI RIVER RIVERBED IN AREA OF RAINBOW DAM DURING RESERVOIR WATER DRAWDOWN
By angelamontana

Posted: September 20, 2022

GREAT FALLS, MT – On Sept. 25 NorthWestern Energy will begin drawing down Rainbow Reservoir about 11 feet from the current full-pool level to replace wooden flash boards on the face of the dam.

“The wooden flash boards were last replaced in 2004,” said NorthWestern Energy Hydro Plant Foreman Dereck Besich. “The aged boards are leaking water which requires a high level of maintenance and frequent repairs. Replacing the boards will reduce maintenance and make the dam perform more efficiently.”

The reservoir water drawdown will begin Sept. 25. Over the next five days the construction project will involve removing old boards and replacing with new ones. The reservoir will be back to full pool by Oct. 6.

People and pet should not enter the riverbed. Deep mud, slippery rocks and the short duration of the water drawdown will create safety hazards.

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