New Yellowstone River bypass channel awaits dam’s completion before opening for fish, boaters

Although its waters have long nourished Montana, the Yellowstone River has a reputation for being untamed, forceful and during high spring runoff extremely destructive.

So a new two-mile long channel that should be connected to the river by spring 2023 seems as out of place as a green golf fairway in a beige desert. The channel’s manicured rock and soil banks have been sloped with precision to a 40-foot wide, curving channel that looks more ready for barge traffic than canoes and jet boats.

Mostly finished last summer, the channel is designed to provide fish – especially endangered pallid sturgeon – a route around Intake Dam to reach spawning habitat upstream. With the bypass, the big fish and other species will be able to swim another 165 miles upstream, reconnecting portions of the river cut off since the dam was completed in 1905 to divert water to irrigators plowing Eastern Montana’s prairie.

“I am excited for the construction project to be completed so we can see how the fish respond,” said Mike Backes, Region 7 fisheries manager for Montana Fish, Wildlife & Parks.

Dam

Before the channel 13 miles east of Glendive can be opened, contractors have to finish building the new diversion dam at Intake. More than half has already been constructed on the south side by driving steel pilings deep into the river bed to anchor a sloped concrete structure.

The dam had to be moved about 20 feet upstream after contractors began driving steel piers and hit strong resistance, possibly rock from the old dam. The resistance pushed construction back into 2020 as the route was realigned.

The total cost for both projects is expected to run somewhere between $40 million to $50 million. Construction began in 2019, but the project has been discussed, designed and redesigned, along with weathering environmental groups’ lawsuits since it was first proposed more than a decade ago.

Joe’s

The new bypass replaces old side channels that have been filled in, smoothed over and replanted on Bureau of Reclamation land known as Joe’s Island, a 1,300 acre parcel that will be reopened to the public when work is finished.

“The side channel didn’t get water until the river hit 30,000 (cubic feet per second),” said Dale Lentz, a Bureau of Reclamation scientist who helped design the feature by building models in a Denver warehouse. “This new bypass channel will flow year round, so it’s providing new habitat.”

The channel was built to divert 17% to 30% of the Yellowstone’s flow.

By having water year-round, the bypass will also give boaters a route around the dam.

“I love it,” Lentz said. “I can’t wait to bring the canoe through it.”

“This channel will definitely be a perk,” echoed David Trimpe, the Bureau’s fish biologist working on the project. “You will be able to launch upstream or downstream and boat through.”

Design

Engineering such features in a free-flowing river like the Yellowstone is a one-of-a-kind job, Trimpe noted. The bypass channel was based on a similar feature on the much smaller Tongue River, a tributary to the Yellowstone that enters near Miles City.

“We fixed a lot of things we think are wrong with that one,” Trimpe said, such as making the bottom of the new channel smoother to allow fish like pallids an easier path upstream.

“Pallids prefer slower moving, gentle channels,” Lentz said. “That’s why this is so long, to get a gentle slope.”

To ensure the channel performs as designed, the Bureau of Reclamation has signed an eight-year adaptive management program.

“If it’s not working, we’ll figure out why and change it,” Limpe said.

But Lentz is confident that with all of the studies he’s done the bypass channel will work.

To verify the bypass channel performs as advertised, FWP and the Bureau of Reclamation ran a four-year fish telemetry study – between 2015-2018 at Intake – it will be used as a baseline for fish passage at Intake, Backes said.

“Many of the transmitters used were also active in 2019-2021, so additional data and knowledge is being collected beyond the initial four years,” he said. “The same four-year study will occur after the bypass channel is opened to determine how the project changes fish passage at Intake and habitat usage upstream. The studies include transmitters in pallid sturgeon, shovelnose sturgeon, paddlefish, blue sucker and sauger.”

FWP fisheries biologist Mat Rugg, who worked on the baseline study, said he’s anxious to see how the bypass channel performs.

“It’s really the first of its kind built specifically for sturgeon movement,” he said.

He also noted that from a state perspective, the other native fish species are also important.

Irrigation

Another manmade impediment to the fishes’ survival was the irrigation canals that are fed by Intake Dam. In 2012 a new $19.3 million headgate structure was finished, including screens to help reduce fish becoming trapped in the canals.

Before the new screens were installed, an estimated 400,000 to 1 million fish were sucked from the river each year. The screens can’t stop larvae from entering, since they are so small.

The Lower Yellowstone Project draws 1,374 cfs of water from the Yellowstone River, which this year is running extremely low – only 2,250 cfs.

During low flows in 2012 the project wasn’t able to draw its allotted water after the U.S. Army Corps of Engineers said a permit was needed to add rock to the existing dam.

The average flow in the river for this time of year is 10,600 cfs, but with no dam to impound the Yellowstone’s spring runoff, flows fluctuate widely. The historical high flow was set in May 2011 when the river hit 125,000 cfs.

Water from the Lower Yellowstone Project irrigates about 56,000 acres of corn, sugar beets, alfalfa, wheat, barley and rye.

Survival

The survival of wild pallid sturgeon is not riding on the success of the bypass channel, thanks to years of capture operations by fisheries biologists. The adult wild fish they netted were milked for eggs and sperm so fish could be raised in federal hatcheries and then released back into the river.

According to the adaptive management plan, the U.S. Fish and Wildlife Service has “been releasing hatchery-origin pallid sturgeon (HOPS) in the Missouri and Yellowstone rivers since 1998. The survival estimate for the HOPS has declined in recent years but is still estimated at 16,444.”

The planted fish gave the species some time, but with the bypass channel at Intake it is hoped pallid sturgeon may be able to successfully reproduce on their own once again. The key is for the fish to spawn far enough upstream that their larvae – which float downstream as they develop – to have enough distance to drift before encountering the dead calm waters of Lake Sakakawea in North Dakota. Since the species has adapted over millions of years to live in free-flowing rivers, the larvae die in the calm reservoir waters.

Pallid sturgeon were listed as an endangered species in 1990.

“It’s a huge-scale project,” said FWP’s Rugg. “That bypass channel is massive.”