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Missoula Valley Water Quality District
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Missoula Valley Water Quality District

Department: Water Quality District
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Water Quality District

Clark Fork Channel Migration Zone Pilot Study

We’ve grown accustomed to our rivers and streams staying in their current location. Over the past ten years they don’t seem to  have moved very much, so it seems like they might stay that way forever.  But the fact is that streams naturally migrate across their floodplains over time, and in response to large events such as floods or ice jams.  Former active river channels are readily visible in aerial photos of the Missoula Valley.  Historic photos also show a long term pattern of channel migration. Despite our best efforts to control them,  streams eventually reclaim their former channels and floodplains, often resulting in catastrophic loss of life and property. 

If you are planning a project along the Clark Fork River, you might want to check out the results of a recent study of the river’s channel migration.

In December, 2009 the Missoula Water Quality District released a pilot channel migration study for a stretch of the Clark Fork River downstream of Missoula to Huson.  The study documents where the channel has been historically - and where it may be again within the next 100-years.  The study and associated maps are available for download here:


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