Milltown Dam Removal

Another milestone in the removal of the Milltown Dam was achieved this week when the Clark's Fork River was re-diverted to its original channel.  In 2006, the Clark's Fork was diverted into a man-made channel to begin the process of removing approximately 2.2 million cubic yards toxic sediment. The toxic sediment was loaded onto train cars and shipped to the ARCO-BP repository near Opportunity, MT.  The last load was hauled away in 2009.  Although 2.2 million cubic yards of toxic sediment were removed, there was an estimated total of 6.2 million cubic yards of sediment on sight.  The obvious question arises, what happened to the excess 4 million yards of sediment?

In recent years, the removal of dams have become a rallying cry for river coalitions around the country. The removal of Milltown Dam was on the front lines of this battle.  In 2008, the Milltown Dam was breached and for the first time in over a century the Clark's Fork river flowed freely.  However, when the dam was breached, it released more sediment than any other dam removal in U.S. history.  A study done by the University of Montana in 2008 found that sediments containing arsenic and copper were not only being deposited 50 kilometers further downstream but at 3 to 5 times the concentration than pre-breached levels.  It has been reported, that some of the sediment has traveled 100 miles downstream and settled behind the Thompson Falls Dam.  It became apparent during the fishing season of 2008 that the removal of the dam would have some drastically negative effects to the fishery.  Over the last few years, the mayfly hatches on the Clark's Fork have been a mere shadow of years past.  The Trico hatch, which once came off in blizzards, is now almost non-existent.  The same can be said for the Baetis.  Furthermore, where there once was clean cobblestone and pea-sized gravel, there are now sand bars of silt.  Another unintended consequence, was the fact that behind the Milltown Dam resided a very large population of Northern Pike.  There was always a population of pike below the dam, but since the removal of the dam the amount and size of pike being caught have both increased.  The fall in productivity of the Clark's Fork has also led to increased pressure on the Bitterroot River.  More and more Missoula anglers are fishing the Bitterroot while the Clark's Fork heals.

In 2009, Gov. Brian Schweitzer was one of the first and only people to float and fish the unobstructed Clark's Fork and Blackfoot intersection (the section remains closed to floating).  During that trip, it was reported that Gov. Schweitzer caught a 17" inch Westslope Cutthroat (According to the most recent article in the Missoulian newspaper, the fish story had grown and he allegedly caught a 22 incher.  I guess the governor is a true fisherman!)  The Milltown Dam project has been heralded as a environmental success story.  There is no question, that in the long-term, the removal of the dam will only benefit trout populations, not only on the Clark's Fork, but also the Blackfoot, the Little Blackfoot and all the tributaries located upstream of the old dam site.   FWP has already reported higher fish concentrations upstream of the old dam site. However, the negative effects on the Clark's Fork downstream of the old dam site will be felt for years to come.  Will the fishery ever truly recover?  Only time will tell.