GREAT FALLS – NorthWestern Energy is planning to draw down the reservoir above Rainbow Dam in Great Falls beginning Monday.
The drawdown will allow crews to perform maintenance on rubber dams that are an essential part of the operation of Rainbow Dam, according to a press release from NorthWestern Energy.
The drawdown is designed to bring the water level down to the crest of the dam, which will allow crews to work safely. The drawdown, which will likely take a full week, will reduce the water level in the reservoir by 12 to 13 feet.
The maintenance work is expected to last several days and once completed, the reservoir levels will begin to rise to normal levels.
NorthWestern urges people to use caution around the reservoir during the drawdown and fluctuations in water levels.
NorthWestern Energy, working with Montana Fish, Wildlife & Parks, will also take advantage of the drawdown to do excavation work at the boat launch site on the north side of the reservoir. Sediment accumulation in recent years has limited the use of the launch to very small boats. The excavation is intended to increase recreational access to the reservoir.
NorthWestern Energy and the Missouri-Madison River Fund, a program with several participants established to enhance recreation along the two rivers, will pay for the excavation work, which is expected to cost between $25,000 and $30,000.
Reporting by David Sherman for MTN News