October 12, 2021
By Sean F. Britt
This article originally appeared in the Oct-Nov-Dec 2017 issue of Fly Fisherman magazine.
In June 2013, days of heavy rain on top of melting snowpack created a crippling flood in the Bow River watershed that killed five people, caused $5 billion in damages, and virtually erased the old riverbed. Islands were removed, riverbanks eroded, new gravel bars were created in farmers’ fields, and trout were left swimming in the streets of downtown Calgary as the water receded.
For decades, fly fishers around the world knew the Bow as one of the greatest trout fisheries in the West, but after the flood, many were left questioning if the Bow would lose its blue ribbon status. Was the Bow lost forever? Was it even worth fishing anymore? Four years later, the results are in. Fishing is as good as it’s always been—maybe even better. In a river that has always been known for large trout, the trout in the post-flood era on average are even beastlier. And new infrastructure and a proposed Bow River Access Plan could mean a reboot for the Bow River.
The Bow River's Perfect Storm
On the evening of June 19, 2013, the rain began to fall and didn’t stop for three days. A low-pressure system about the size of Tennessee became trapped along the front ranges of the Rocky Mountains, held in place by surrounding high-pressure systems.
Three days of rainfall totaled 8 to 14 inches in some areas, rainfall similar to a tropical storm. This, combined with a large remaining snow pack at higher elevations from a cool spring, and partially frozen or saturated ground, led to the worst flooding in southern Alberta since 1883. Flow in the Bow River peaked at 1,750 cubic meters per second (61,800 cubic feet per second, or about six times its normal peak rate).
Local emergencies were declared in 32 communities over an area the size of Maine, and more than 2,200 Canadian Forces troops were deployed to help with rescue efforts and a monumental cleanup. Thousands of volunteers also helped people dig out and dry out their homes while businesses and governments assessed the damages.
A local fly-fishing guide noticed fish stranded in pockets of water formed by the receding river and helped bring together volunteers to conduct emergency fish rescues for fish stranded in these isolated areas. Over 5,000 fish were rescued with the help of Trout Unlimited, the government of Alberta, and dozens of good Samaritans from the fly-fishing community. While the impact of the rescue on the fishery is not known, we do know that flood events negatively impact eggs and year of the young. Given this potential loss of an entire generation, it’s easy to envision that the 5,000 fish rescued may have become pioneers of life after the flood.
The Aftermath of the Bow River Flood
A few weeks after the flood, I took a walk along the Bow. Access to the river was significantly restricted because most of the boat launches were destroyed, but on foot I was astounded by the massive changes. New river channels were created where there wasn’t anything before, entire islands were washed away, and mounds of river cobble were piled on shore over 10 feet high in places. Debris was everywhere. One area even exposed an old buffalo jump eroding from the riverbank, with bones and stone tools dating back thousands of years.
Despite the lack of functional boat launches, guides and recreational anglers were back fishing parts of the river within a few weeks. When I asked how the fishing was during the following summer, I got mixed reactions. Some said the fishing had deteriorated, others said it was the same, and another contingent said it had improved. Whatever your take was, one thing was certain: The Bow was a “new to you” river that forced even veterans to reboot their fishing habits. Prior to the flood, many fly fishers visited the same locations day in and day out. After the flood, those “go-to” holes, riffles, and runs were no longer there. Everyone had to start from scratch and find the fish all over again.
For some people, having to read new water, explore, and experiment was exciting. For others, it was frustrating. Personally, I loved the reboot. It forced me to go places I hadn’t been before, try different flies, and even fish water I previously didn’t consider. One of my biggest discoveries after the flood (confirmed by others) was that new microtopography had formed in the middle of the river such as mini-depressions in a flat just large enough to hold one or two fish. Other, more noticeable habitat changes included the disappearance or creation of gravel bars, the filling in of old undercut banks, and the creation of new ones.
Another reason why fly fishers had varying success levels post-flood lies in flies and methods. Research shows that a major flood event like 2013 essentially flushes the system. The violent force of flowing water cleans the river bottom, moving out old cobble and redepositing new unconsolidated cobbles and gravels. Vegetation is also wiped away. This translates into poor nymphing conditions, but better terrestrial and dry-fly action. After the flood, most successful anglers had better dry-fly fishing than in previous years where nymphing had previously been the most popular and productive style of fishing. I can personally attest to this as I experienced some of my best ever grasshopper and caddis dry-fly fishing in 2013 and 2014.
Fishing in 2015 and 2016 was a different tale: big fish in big numbers. By mid-2015 a buzz started about big rainbows. Guides reported catch rates of a dozen fish over 20 inches with many over the 2-foot mark per day, not counting the smaller ones. We were also seeing beefier brown trout, but fewer of them, perhaps because they don’t typically fare as well in catastrophic floods, or due to the impact of Saprolegnia fungus that has been affecting them the past few years.
In addition to big fish, we started to see a rebound in vegetation in the river, which meant bugs were back and nymphing was back on the rise. In those years we saw a big Skwala stonefly hatch, a decent Golden Stonefly hatch, thick blankets of caddis, and a longer and massive March Brown hatch. It was also hard to miss the staples of the river: PMDs, midges, and Tricos.
Big Fish on the Bow River
The presence of these big fish is directly attributable to the flood. The violent flows that swept away cobbles, gravel, and vegetation also swept away any eggs or vulnerable age class of fish like year of the young, leaving older, bigger fish with less competition, better food sources, and better living conditions. All those big fish meant bent hooks and busted leaders.
We had to adapt to these bigger and stronger fish by using thicker leaders and heavier hooks. Where we used to tie on 4X or 5X tippet for dry flies, 3X became the norm. For nymphing, the standard became 0X to 2X, and streamer fishing became straight 15-pound test or 20-pound test Maxima. The trout in the Bow River became so big and strong after the flood that we had to do anything and everything we could to give ourselves a fighting chance. As one guide put it, “If the leader fits through the eye, use it.”
In addition to seeing bigger fish, it is also common for fisheries to have an upturn in population after a major flood. Despite losing eggs and year of the young during the flood, the river gained more viable spawning grounds for future generations. As vegetation gets swept away by a flood, cleaner gravel is left behind, providing more and better quality areas for fish to develop spawning grounds (called redds). A comparison of redd count studies between from 1999 and 2015 clearly demonstrates that spawning improved on the Bow River, with some spawning areas recording over 100 more redds in 2015 than in 1999.
The flood produced other long-term impacts. Reservoirs in the entire watershed were short-term managed to prevent or mitigate a future flood event—one that simply didn’t come. The reservoirs were kept low through the spring, but when the snowmelt passed and summer came, the dam operators had to retain as much water as possible, resulting in low summertime flows. In 2015 there was a lengthy fishing closure due to high water temperatures brought about by low flows and hotter-
than-average weather. The river closure severely impacted local shops and guides, and reduced the overall angling pressure. However, when temperatures dropped, and the river reopened, the fishing was as good as ever, maybe better.
The renewed Bow with its current robust trout population has some challenges to face in the years ahead. Climate change is one hot topic. The river was almost closed again in 2016 due to low flows and hot weather. Average temperatures are rising across Canada between 0.5 and 1.5 degrees, with local temperatures in the Rockies rising by 2 degrees.
This is significant for the Bow, given that about 80 percent of its water comes from mountain snowpack. This warming trend may translate into less snow, earlier springs, and less water in the river. Less water creates the potential for additional closures, the spread of disease, and increase in trout mortality. This water loss can already be seen along the upper Bow in Banff, where average flows have decreased by about 12 percent over the last century. One tributary, Marmot Creek, has lost about 25 percent of its annual flows over the last 50 years.
Whirling disease was first confirmed on the upper Bow in Banff National Park in August 2016, and later confirmed in the entire watershed. The disease was also detected in five commercial aquaculture facilities. Officials haven’t confirmed how long the disease has been in Alberta or how it got here, but many biologists and outfitters believe it has likely been here for 20 years or more with no observable negative effects.
Despite these issues, there are exciting and promising initiatives on the horizon. A new agreement between the province of Alberta and hydroelectric operators was signed in mid-2016. This, along with an Emergency Trout Streams Closure policy in development by the Government of Alberta, will hopefully allow for better management of the watershed during drought years, lessening the potential impact to the fishery and the community that depends on it for their livelihood. New fishing regulations for 2017 made the entire Bow River a catch-and-release fishery, and the province is discussing additional protection measures for the river, including possible new parks and protected areas.
The City of Calgary plans to develop 25 new access areas on the Bow River by 2022. This will help not only provide more opportunities for fly fishers and other water recreationists, but also better distribute user pressure along the river. The proposed accesses include nine full-service boat launches inside the city limits by the end of 2019.
The Province is also stepping up its involvement in Bow River management, and in the summer of 2017 released a draft Bow River Access Plan centered on improving access at public facilities at its five major access sites downstream from the city: Fish Creek Provincial Park, Policeman’s Flats, McKinnon Flats, Legacy Island, and Johnson’s Island at Wyndham-Carseland Provincial Park. All these access areas are in the river’s flood plain and were severely damaged by the 2013 flood.
Double-lane boat launches, proper bathrooms, improved signage, adequate and regulated parking areas, are all parts of the proposal to make the Bow River experience better for all users. After a July public input period, a revised draft of the plan is expected in October 2017. To download the complete plan, visit talkaep.alberta.ca and search for “Bow River Access Plan.”
The Bow is back and continues to be worthy of its blue ribbon status, but we cannot take it for granted. It continues to face a wide variety of challenges—from the impacts of climate change to increased angling pressure and conflict over how the river and its water is managed. The best thing we can do is practice best angling techniques and become part of the management conversation to ensure the fishery is represented and can be enjoyed for generations to come.
Bow River Q&A with Ross Purnell
I was born in Calgary in a hospital overlooking the Bow River, skipped classes at the University of Calgary because of Blue-winged Olive hatches, worked as a guide on the river for quite a few years, and ended up as the editor of Fly Fisherman, due in great part to the influence the Bow River had on my life. In my travels I meet many experienced fly fishers from around the world—most of them have heard of Alberta’s Bow River, but surprisingly few have fished it. Here are the questions I most commonly get about my home river, along with the short answers.
Q: I’ve heard the Bow is a driftboat river. Can I successfully wade there?
A: Trout in the Bow commonly feed close to the banks and while casting a grasshopper to the bank from a drift boat is easier, wading is almost always a viable option from Fish Creek Provincial Park or one of the four other public boat launches downstream. The law in Alberta is similar to Montana. Once you gain legal access you can walk/wade below the high-water mark as far as you’d like. Be safe. All big Western rivers are dangerous during peak flows.
Q: When is the best time to fish the Bow?
A: Traffic peaks on the Bow during the first two weeks of July because of the other huge tourist attraction: The Calgary Stampede. The fishing is generally pretty good at that time, but unless you’re a huge rodeo fan, you should stay away. June is a crapshoot due to spring snowmelt. Some of my best days on the Bow have been August hopper days, but if it gets too hot, the fishing can go downhill. May is incredible, and so is September.
Q: What flies do I need?
A: Calgary has six full-service fly shops, so you can pick up the current “hot” flies when you’re there. The trout are far less picky about specific fly patterns than many other places. Finding the fish and presentation are most important. Be prepared to fish streamers, nymphs, or drys, depending on the time of day, season, and the water type.
Q: Is the Bow really the “best” trout stream in the Rockies?
A: The answer is extremely subjective, but I have to say “yes.” There are other places with many more trout, more majestic scenery, and places with more consistent dry-fly fishing, but the Bow has bigger trout (on average) than any river in the Lower 48 states. —Ross Purnell
Sean Britt is an environmental consultant, freelance writer, angler, and fly tier. He lives in Calgary with his wife Nicole, son Ben, and dog Bizzy.