Yellowstone River changed after massive flood, but what happened to the trout? Anglers find out.

Fishing Montana's Paradise Valley was an altered experience due to the massive summer flood, but anglers were relieved to find that trout are resilient.

In July of 2021, Montana fly fishing guide Zach Pleshar emailed clients, warning of potentially difficult drought-like conditions on the Yellowstone River: low water and rising water temperatures – a stressful, and sometimes lethal, combination for trout that thrive in cold, oxygenated water.

Nearly a year later in June – after massive flooding on the Yellowstone and some of its tributaries – Pleshar sent an email: “We will probably be fishing the Yellowstone by the first week of July, like we do on average years. We'll see how the flood impacted it … but I do think we will have trout to fish to.”

The Yellowstone, one of America’s iconic rivers, had trout.

My friend Grover Thomas and I caught them during a recent trip to Montana’s Paradise Valley, a stunning landscape with the Gallatin Range to the west and the Absaroka Range to the east, and the Yellowstone River snaking through the valley as it exits Yellowstone National Park and flows through Livingston, Montana, toward the town of Big Timber.

The question anglers had – and have – is: How did the flood affect trout fishing?

It was an altered experience that included warmer and muddy water and the reality of climate change in a hotter West. Nearly every important story out of the West revolves around water and its relationship with people, ranching, wildlife and others who make a living on rivers.

A stretch of the upper Boulder River, not far from the old mining ghost town of Independence. Native cutthroat trout dominate this section of the river.

Trout are resilient

I have fly fished the Rocky Mountain West for 25 years – Utah, Colorado, Wyoming and Montana – and for the past five years, Montana’s Paradise Valley region and the northern section of Yellowstone National Park, where the Yellowstone River is an imposing force.

The Yellowstone, the longest undammed river in the U.S., is 678 miles long from its headwaters in Wyoming to where it empties into the Missouri River in North Dakota. The Yellowstone and its tributaries are a riparian haven.

I first learned about this area in the early 1990s from reading Jim Harrison and Thomas McGuane, two wonderful authors who wrote, among many topics, about fly fishing in Montana. I knew it was a place I would someday fish.

It is also where you can get a burger at the Murray Bar, a four-star meal at the Yellowstone Valley Grill, buy a signed copy of valley resident and grizzly bear expert Doug Peacock’s book “Was it Worth it? A Wilderness Warrior’s Long Journey Home” at Elk River Books and mingle with ranchers, outdoor enthusiasts and tourists at the Old Saloon.

And fish for brown, rainbow, brook and cutthroat trout.

The sun sets behind the Gallatin Range in the heart of Montana’s Paradise Valley, near the town of Pray.

The river has changed since a rare combination of more-than-usual rain and snowmelt overwhelmed the Yellowstone on June 13, sending 52,000 cubic feet of water per second downstream. A cubic foot of water is about the size of a basketball, meaning the equivalent of 52,000 basketballs of water per second gushed – more than the previous record of 38,000 CFS. 

“The river has changed in a lot of places,” Montana Fish, Wildlife and Parks fisheries biologist Scott Opitz told me last month. “There’s new channels, and a lot of habitat change occurred through this event. But it hasn’t been as significant as I thought it might be, mainly because while the peak was very high, it wasn’t very long. It’s too early what the overall impact on the trout is.

“What we have seen in the past from large flood events is that it’s not a one-and-done thing. The river continues to adjust for another two, three years.”

A brown trout caught on a guided float trip on the famed Yellowstone River.

The flood also had a significant impact on Yellowstone National Park, where access to the north and northeast entrances to America’s first national park was closed and remains limited. Flooding washed out roads, making it just about impossible to fish popular angling spots such as the Lamar and Gardner Rivers.

In fragile ecosystems sometimes battered by flooding, warm water and low water, trout are resilient. As Opitz explained, in high-water events, trout find calmer water along the banks and move to the floodplains over the banks, then move back to the main river when the water recedes.

For native cutthroat trout, June is spawning time, and they spawn in tributaries, which Opitz said, “provide great refuge for fish in high-water events. Browns and rainbows will use those as well, but Yellowstone cutthroat are really good at not being in the main Yellowstone when we have big flood events.”

Moonshine-clear water and cutthroat

Grover and I arrived in Bozeman, Montana, late morning, taking an early flight so we could spend some time on the water that day. Before heading to a tributary of the Yellowstone, we stopped at a sporting goods store for bear spray. In grizzly country, it’s a necessity. While grizzly encounters are rare, they happen. The occasional “hey bear” while hiking or fishing helps reduce the chance of running into a bear, but you want to be prepared.

Our attempt at fly fishing for native cutthroats that first day started well even as lightning and thunder appeared deep in the backcountry. Shortly after catching a cutthroat, I noticed the creek turn from moonshine clear to chocolate milk muddy in a minute as the water rose by about six inches. That storm high in the mountains created a mess, and it was a harbinger.

Our fishing was done for the day, but that gave us an opportunity to make it to the Old Saloon in Emigrant, Montana, for Mike and the Moonpies, an alt-country honkytonk band. 

The Boulder River called the next day. At first, I was hesitant to name this river, which starts high in the Absaroka Beartooth Wilderness, not far from Yellowstone National Park. From its headwaters, it flows north for about 60 miles until its confluence with the Yellowstone River near Big Timber. The dry fly fishing was fantastic, mostly rainbows and cutthroats eager to gobble an imitation bug.

We fished the Boulder for three days, and each day fished better than the previous one. I don’t mind naming the river because it’s mentioned often in several guidebooks dedicated to Montana’s best trout streams. The higher up you go, nearing an old mining ghost town, the river requires navigating massive, slick boulders to get from pool to pool. (I have recently crossed an age Rubicon: I wore earplugs to a Rage Against the Machine concert and purchased a wading staff for navigating the slippery rock bed and tricky currents of Western rivers.)

Landing a cutthroat trout in a tributary to a tributary of the Yellowstone River in Montana’s Paradise Valley. This small stream is loaded with trout and is a hidden gem, as most anglers are drawn to the bigger, more well-known rivers and streams.

On a Monday, we floated the Yellowstone River with a guide in a drift boat – one of two days we had scheduled on the Yellowstone. Because of the rain a couple of days earlier, portions of the Yellowstone we wanted to fish were too murky for good fishing, so we headed east to find clear water. We caught brown and rainbow trout on and off for most of the day.

North of the park on the ’Stone, we saw a washed-out bridge that needs to be removed from the river. An eight-mile stretch of the Yellowstone is closed to water traffic because an out-of-use train trestle is on the verge of collapse, and fishing access sites are closed because of damage caused by the flood.

Riverbanks have eroded, and lodgepole pine trees swept from the park came to rest miles downstream. Driving south on Highway 89, Pleshar pointed to a tree and said, “See that green canoe.” The canoe was lodged in a tree, about 20 feet above the river. It got stuck there during the flood, re-emphasizing an angler’s creed: It’s never the same river twice.

'Summer was just about canceled'

Richard Parks is the owner of Parks’ Fly Shop, sitting high above the Yellowstone River in Gardiner, just a few long casts from the north entrance of YNP. The fly shop has occupied a physical presence in Gardiner since 1953, when Parks’ father, Merton, opened a location.

With visitor traffic to that area limited, Parks had a significant decline in sales – he estimates they are guiding at 35% of what his business does in a normal summer – including guided trips into YNP.

“Our summer was just about canceled,” Parks told me, adding, “It’s a huge impact on my business but less of an impact in some respect than on other folks. I don’t have a mortgage or rent. To some degree, I scaled my expenses. But a big chunk of our business is pass-through traffic. It’s not going to be a good business year, but it’s not a total wipeout.”

Grover and I did not fish any portion of YNP on this trip, and that was disappointing. That region, including the renowned Lamar Valley, is home to several creeks and streams, such as the Lamar River, Soda Butte Creek, Cache Creek and Slough Creek.

Teeming with wildlife – bears, bison, wolves, ungulates, badgers, birds – the Lamar Valley is called America’s Serengeti. However, access was shut off as a result of the flooding. 

Steve Carpenter, a gastroenterologist from Savannah, Ga., scheduled a backcountry trip into the Lamar Valley for late August to hike, camp and fly-fish. It requires extensive planning since backcountry camping spots are reserved months in advance. Carpenter and two friends had their premier spot near the confluence of Cache Creek and the Lamar River.

“We try to do a backcountry fly-fishing trip every year until we can’t do it,” Carpenter said. “Then the flood happened, and they told us there was a closure. We immediately went to see what our other options were because we wanted to fish in the Park and we wanted to camp. Then we began to look at the southwest corner and found those sites were also booked.

"We ended up using the walk-up service to get a site but you had to be there 48 hours ahead of time and take what you can get. It was very remote and very scenic with nobody around. The flooding did affect us in that we changed our plans 100%.”

Hoping for a trout rebound

Grover and I had one more float trip for the Yellowstone planned, but a storm moved through the area the day before and turned it to mud. We decided not to fish, and it was a good decision. The reports from guides for the next three days were not good. One guide relayed to Pleshar, “The Yellowstone felt broken today.”

With so many fresh-cut banks from the flood, a strong rainstorm turns the river from clear to turbid for a few extra days, whereas it used to clear up after a day. Once the Yellowstone cleared in late August, the fishing returned to normal as Pleshar and Opitz expected. Opitz and his team will conduct fish estimates in the spring.

In Big Sky country, brown trout thrive along the deep-cut banks of rivers.

“In the 1996-97 floods, we saw a little bit of a drop in trout population but they rebounded like crazy, and the same thing after the 2011 flood,” Opitz said. “We’re dealing with an event now that is magnitudes higher than events we’ve seen in the past. It’s still a bit of an unknown, but we’re hoping it follows that historical trend.”

On our final day in Paradise Valley, we fished a small stream – a tributary to a tributary of the Yellowstone. In a stretch that is so narrow a long jumper could clear bank-to-bank, Grover caught a solid 16-inch rainbow.

Unfortunately, another angler had the caught the fish prior but broke it off, leaving a fly attached to the trout. Grover released the fish, and it took off to safer waters. As it swam away, it took the broken-off line from the previous angler, and the attached fly hooked deep into Grover’s middle finger. That required a trip to urgent care, a shot of lidocaine and removal of the fly. Plus a tetanus shot and antibiotics.

But what is better: to have caught fish and gotten hooked in the finger or to have not caught fish at all? We know the answer.

Catching monster fish in a secret spot

I spent one more day fishing with Missoula-based author, poet, teacher and fly fishing guide Chris Dombrowski. His new book, “The River You Touch: Making a Life on Moving Water,” comes out Oct. 11. It is a poignant rumination on marriage, parenthood, friendship and what it means to connect with nature.

"The last several years, for whatever reason, put me in a place of feeling less hope than I had before," Dombrowski said. "But I had this hunch that if I could dig back into the lives of our children and their experiences in the natural world, that I would find my own sense of wonder rekindled."

Dombrowski sent me a text the day before our outing: “It’s a little bit of work but the idea is to get on a small, secret stretch of water.” I won’t divulge the name of this water because I’d like to fish again with Chris and more important, I don’t want a natural resource overfished and ruined.

Fishing a hard-to-access stretch of river with author and fly fishing guide Chris Dombrowski, it was time to chase big brown trout using grasshopper imitation flies.

Trout are imperiled in some rivers, with climate change playing a role. Even as this part of the country transitioned from summer to autumn, the daytime temperatures remained in the high 80s and 90s as overnight lows dipped into the 50s. In early September, a few Montana rivers, including the Madison, Ruby, Shields, Smith and Sun, were under hoot owl conditions, meaning the rivers were open to fishing only from 6 a.m.-2 p.m. to ease stress on trout and not catch them when conditions can be fatal.

In a study published in January in "Science Advances," University of Montana researchers found that climate change and invasive species have reduced native trout populations in the state and will continue to do so. Parks is worried about a coldwater fishery turning to a smallmouth bass fishery, and earlier this year, scientists detected smallmouth DNA just north of YNP, not far from Parks’ Fly Shop.

“In the next few years, I expect things to be normal,” Parks told me. “But in the long-term, the politicians need to get off the dime and do something about climate. I’m not looking forward to the Yellowstone becoming a smallmouth river.”

Dombrowski and I pondered these issues as we sought and caught big browns. “If we just give these trout the bare necessities in terms of water flows, they can rebound from just about anything," he said. "It’s habitat. It’s all they really need, and you put water at the top of this list.

"You and I went fishing and were able to find a clean stretch of water and throw dry flies to large brown trout without another person out there. It’s still possible.

“There’s no hope without optimism.”