MSU students study Big Hole River watershed to help native fish

MSU students study Big Hole River watershed to help native fish

Source: MSU News Service
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Marshall Swearingen

WISDOM – When Montana State University graduate student Ben Triano stepped into a deep riffle in a tributary of the Big Hole River in late July and the water nearly brimmed his chest-waders, it was a good illustration of how immersed he’s become in an MSU summer research project.

Since May, Triano and another MSU graduate student, Nolan Platt, have been working 12 hours per day, eight days at a time, using a camper parked behind the U.S. Forest Service ranger station in Wisdom as their home base. Most of that time you can find the bearded, wader-clad duo standing in a stream, collecting data that could help Montana’s arctic grayling.

Triano and Platt are studying 17 sites along the Big Hole River and its tributaries. At those locations, fish ladders help grayling navigate structures that divert portions of the streams for irrigation. The ladders, also called fishways, allow the fish to migrate to cooler waters when the river heats up during the summer.

More than 50 fish ladders have been installed in the upper Big Hole River Valley in recent years as part of a cooperative program involving local landowners, Montana Fish, Wildlife & Parks, the U.S. Fish and Wildlife Service, the Natural Resources Conservation Service and the Montana Department of Natural Resources and Conservation. The roughly 8-foot-long metal troughs, in addition to other conservation measures, played a key role in the Fish and Wildlife Service’s decision in 2014 not to list Montana’s grayling — which inhabit only a small fraction of their historic range — as threatened or endangered.

Now, MSU researchers are studying the fishways in order to recommend best practices for their operation.

“This summer we want to collect enough stream data to be able to accurately model the stream-fishway system,” said Katey Plymesser, an assistant professor in MSU’s Department of Civil Engineering and Platt’s academic adviser.

“Then, we can look at different scenarios for each site and, ultimately, determine best managment practices for fish passage,” she said.

Collecting the data is where Triano, who is pursuing his master’s degree in MSU’s Department of Ecology, and Platt, a master’s student in civil engineering, come in.

When Triano stepped into the deep riffle, at Governor Creek, he uncapped a PVC pipe sticking out of the streambed, pulled out a sensor and plugged in a handheld data reader to make the download. Back in the lab, the data would allow the team to calculate how the water depth had changed hourly during the summer, he said.

Meanwhile, Platt set up a tripod topped with a high-tech device for surveying this site, where the fishway was full of water and a smooth waterfall formed over wooden boards that pushed water into an irrigation headgate.

Minutes later, Triano, who is advised by Tom McMahon in the Department of Ecology in MSU’s College of Letters and Science, stood on the stream bank holding the survey prism — a pole-mounted, cup-shaped mirror used to reflect the laser shot from the device on the tripod.

“Can you see this?” Triano shouted as he pushed aside willow branches to clear a line of sight.

“We got it,” Platt yelled back as he registered the survey reading.

Repeating the process across multiple cross-sections of the stream near the irrigation diversion and fish ladder, they’d collect enough data points to create a detailed rendering of the site. That would then be used to model different stream-flow scenarios.

“It’s like making a papier-mache and chicken wire model of the stream, then pouring water over it,” Platt said. “But we do it with a computer.”

When Triano and Platt aren’t mapping the streambed, they’re making the rounds to the different sites, measuring stream flows. Those numbers will be used to calibrate the computer models to the actual conditions the streams experience during the summer.

In addition to downloading the data from the sensors in the PVC pipes, at each of the sites they take manual readings of water depth in the fishway, in the irrigation diversion and in the stream. So far, they’re on track to take six sets of readings at each site.

When they started in May, some of the streams were flowing over their banks, tinted brown with spring runoff, and the duo braced against strong currents when they waded.

As the July day at Governor Creek heated up, Triano and Platt looked ahead to nearly two more months wading the streams.

“This whole valley is a big hydrological system,” Platt said. “You start to get a feel for it.”

Contact: Katey Plymesser,, 406-994-6115.