Milltown breaching will pay off in future

Next week will be bittersweet for trout anglers fond of the Clark Fork River.

The Superfund project to remove Milltown Dam upstream from Missoula is building to a crescendo and scheduled to peak March 28 with the breaching of the dam in what’s expected to be a controlled flood of water laden with contaminated silt.

Yes, fish will die. Lots of them.

Since October, trains have been running seven days a week to haul away accumulated sediment tainted with arsenic and heavy metals that washed down the Clark Fork 120 miles from Butte-area mining and smelting operations. Much of the toxic waste settled in the reservoir behind the dam built in 1908 on the Clark Fork at its confluence with the Blackfoot River.

For scale, consider this: Even though the trains are scheduled to run daily for another 18 months to haul away a total of about 2.2 million cubic yards of mud from the reservoir, the effort will remove only about a third of the contaminated sediment accumulated in the past century.

But that will be enough to make the site safe for the river to begin its natural restoration processes, Environmental Protection Agency officials say.

After the breaching, a surge of water will scour an estimated 300,000 tons of sediment from the mouth of the Blackfoot River. The worst contamination has been removed along the temporary river channel, yet next week’s muddy flood is expected to decimate the portion of the prized trout fishery in the Clark Fork for miles downstream through Missoula.

The carnage won’t subside until sometime after the confluence with the Bitterroot River, which will deliver enough dilution to phase out the toxic impacts to aquatic insects and fish as the surge moves down the Clark Fork, fisheries experts say.

Some 36 hours after the breaching, the off-color water is expected to reach St. Regis, where the impacts to fish and fishermen should be only temporary.

“We’ve been told the fishing could be off as it would in any runoff event for about a week,” said Brooks Sanford of Clark Fork Trout and Tackle in St. Regis, noting that the downstream fishery should not suffer at all.

“When the conditions improve again, we still hope to get some good fishing in before the normal runoff.”

Montana Fish, Wildlife and Parks biologists cringe at what will happen next week, but they remain optimistic.

“Based on past experience with floods that have released toxic sediment from Milltown Reservoir, it could take three to five years for the insects and the fishery to recover,” said Pat Saffel, regional fisheries manager. He was referring to the Clark Fork at least to the Bitterroot and for an undetermined distance farther downstream. “We’ll be monitoring the impacts.”

Since much of the worst contamination has been removed, the recovery could be quicker in this case, he said.

Beyond next week, the outlook is as rosy as the flanks of a trophy rainbow.

Superfund efforts upstream in the Clark Fork drainage resulted in last year’s announcement that trout were showing up in Silver Bow Creek, which had been a flowing toxic death trap for fish for decades.

The $120 million Milltown portion of the vast Clark Fork drainage Superfund project – a cost projection that has grown from $100 million reported last year – is using state-of-the-art environmental safeguards to reduce the restoration’s impacts to fisheries, Saffel said.

Removing Milltown Dam also will address the invasion of exotic fish species.

Northern pike illegally introduced to the Clearwater lakes chain near Seeley Lake moved down the Blackfoot River in the early 1990s to find a perfect environment for colonizing in Milltown Reservoir.

Floods have flushed many doses of pike into the Clark Fork and the infestation spiked a couple of years ago with the Superfund work on the dam, Saffel said.

Indeed, fly fishers have been getting some savage hits on streamer patterns in recent years.

“But by breaching the dam, we’re taking away their upstream spawning and rearing habitat and they should basically fade away (from the flowing portion of the river),” Saffel said.

Dam breaching is serious business that unleashes the ravaging spoils of industry on the natural environment downstream, he said.

“We don’t like doing this to fish, but natural flooding events (through the toxic sediments of Milltown Reservoir) have been causing this type of fish-killing event every 10 years or so for decades. The fishery was in constant stages of recovery from the impacts of the dam.”

“The bottom line for fishermen is that this will be the last time,” Saffel emphasized.

“After this event, the fishery will be able to build to a higher level because it won’t be suffering those constant setbacks.”

Maybe the public will have a better understanding about the high costs of letting industry run rampant over public health and natural resources.

Best of all, starting next week, fish will have the run of the upper Clark Fork, and the Blackfoot, too.

For the first time in a century, the Clark Fork will run free all the way to Thompson Falls.

The potential for the native trout fishery in a cleaned-up free-flowing Clark Fork is known only to anglers who are in their graves.