Trigger point

The Bitterroot River hit historic lows this summer, prompting Montana Fish, Wildlife and Parks to enact fishing restrictions in August. A similar story simultaneously unfolded on the Clark Fork. But even as those restrictions lifted this month, fishing on the crowded Blackfoot River shut down completely for only the third time in a decade.

It was likely a confusing message for local anglers and outfitters, says FWP's Vivaca Crowser. "When you get to this time of year, if we've had closures we're usually looking at reopening, not adding additional ones."

The situation on the Blackfoot developed quickly as the discharge rate approached 500 cubic feet per second going into Labor Day weekend. That figure happens to be a trigger point in the Blackfoot Drought Response Plan, a document established to more evenly distribute sacrifice among irrigators, outfitters and river users. As the river level dropped, the committee responsible for executing the plan discussed recommending that FWP close the waterway.

"On the Tuesday before Labor Day, it had not hit 500," says Blackfoot Challenge Executive Director Gary Burnett. "So the committee looked at the projection and said, 'We anticipate by the end of the week we might hit it.'"

The Blackfoot had been holding steady around 520 cfs, and Crowser says it looked like the agency might "barely slide by." But another development compounded the discussion: A recalibration, or "shift adjustment," at the Bonner gauge station Aug. 28 dropped the discharge rate to roughly 488 cfs. When the drought committee met the following Tuesday, they recommended a full closure.

"It was one of those random things that happened at that exact week and time when things were so close and people were watching so closely," Crowser says, adding it's possible the Blackfoot had hit the closure trigger before the gauge was readjusted.

The USGS, which is responsible for overseeing most of the state's water gauges, tries to visit those gauges 10 times a year, says USGS hydrologic surveillance section chief Wayne Berkas. But with the Blackfoot tracking well below average discharge rates all summer, the USGS has had to pay more visits to the Bonner gauge than usual. "So far, we've made 11 measurements at this site," Berkas says. He's quick to add that the situation's been more demanding on the Bitterroot.

The Blackfoot has slowly climbed back above 500 cfs in recent days. But Burnett says this year presented something of a phenomenon as water temperatures remained well below drought plan triggers despite the lower flows. As the committee revises the drought plan this offseason, these new developments will have to be addressed.

"These conditions are changing," Burnett says. "And we need to go back, look at it and say what did we learn this year that we need to address in a larger conversation."

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