Clark Fork to Flow Free This Month

posted March 14, 2008
by Kevin Colburn

article photo 1

Montana's Clark Fork and Blackfoot rivers are scheduled to flow free later this month for the first time since 1908.  Milltown Dam has blocked fish and recreationists in the rivers for a century - but perhaps more critically has trapped sediment contaminated with toxic heavy metals from an upstream mine on the Clark Fork.  In the late 1990's it was discovered that the aging dam was at high risk of failure - putting downstream areas at risk of being flooded with toxic waters and sediment. It was also discovered that the dam was causing toxic water to seep into local drinking-water wells. 


An elaborate plan was developed over the past decade to remove the dam, remove the sediments, and restore the rivers.  The plan was launched in 2006.  During 2007, reservoir levels were lowered and some of the sediment was removed and shipped upstream by rail to a closed basin repository.  In 2007, a coffer dam was built upstream of the powerhouse and part of the dam, and then those dewatered structures were removed.  To avoid suspension of toxic sediment in the river, a clean and lined bypass channel was built to allow the Clark Fork to flow through the reservoir site.  On Monday, March 17th the Clark Fork River will be allowed to flow through the bypass channel - and then over the remaining spillway of Milltown Dam. 


The week of March 24th, the coffer dam upstream of the old powerhouse site will be breached and the Clark Fork River will once again be a freeflowing river. With the river flowing freely in the bypass channel the through the old powerhouse site, the remaining sediment in the reservoir site and the remaining parts of the dam will be removed, and a natural channel will be restored for the Clark Fork.  Sometime in the 2009-2011 timeframe the river will be introduced to this new channel and the bypass channel removed.  Eventually the valley will be home to a thriving river, trails, access areas, and maybe even a state park. 


American Whitewater played an active role in the FERC process that triggered the decommissioning and removal of Milltown Dam.  Many other stakeholders have worked tirelessly for over a decade to reach this pivotal moment in the restoration of the Clark Fork and Blackfoot Rivers.  The Clark Fork Coalition, the EPA, the State of Montana, and the City of Missoula, and the local residents all deserve a great deal of appreciation from all of us who love healthy and freeflowing rivers. 


You can watch the progress of the dam removal on a webcam hosted by the Clark Fork Coalition.  Learn more at EPA's Milltown Web Page.


FYI - the river through the project area will be closed to boating during the removal activities. 

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