Milltown Dam Nearly Destroyed by 1908 Flood – Would Not Help Now
An official with the Missoula Valley Water Quality District stated categorically on Monday that the Milltown Dam would not have helped to mitigate the flood waters of 2018, and in fact, was nearly destroyed in the 1908 flood.
Environmental Health Specialist Travis Ross explained the original purpose of the Milltown Dam.
“The Milltown Dam was not built as a flood control structure,” said Ross. “It was classified as what they call a ‘run of the river’ dam, meaning that the capability of generating power was solely dependent on the flow of the river. In fact, in times of really high water they would have to take off the flash boards and pass more water out in order to prevent the dam from failing, and interestingly enough, in 1908, just three years after that dam was built we had a significant flooding event that basically destroyed the dam. They had to rebuild a significant part of the dam, so it wasn’t designed to hold flood waters.”
Ross said the dam was responsible for holding back decades of contaminated sediment.
“What it did do was hold back contaminated sediment, so some of that capacity of that reservoir was taken up by sediment, close to three million cubic yards of sediment. In 1997, when a large ice jam went through, a lot of that sediment was released downriver causing a fish kill.”
Ross said the Milltown Dam did not do much in the way of flood control, and would not be helpful in this year’s flooding.
Ross said the removal of the Milltown Dam and the redesign of the river bed below the dam was completed in 2008.