Banff Is Spending the Next 10 Years Undoing a Century-Old Mistake

A century ago, putting more fish into Banff's mountain lakes seemed like a good idea.

Today, Parks Canada is spending the next decade taking some of them back out.

For generations, millions of non-native fish were deliberately stocked throughout Banff National Park to create better fishing opportunities. At the time, it seemed like a good way to help people enjoy the outdoors.

We know more now.

Those introduced fish changed aquatic ecosystems, competed with native species and contributed to the decline of fish that had evolved in these waters long before Banff became a national park.

So this summer, something unusual is happening.

Parks Canada has begun a 10-year aquatic restoration effort designed to remove non-native fish from several Banff watersheds and, where they historically occurred, bring back native Westslope cutthroat trout and bull trout. The program is scheduled to run from 2026 through 2036.

The latest work began at Fish Creek near Lake Louise on August 24.

But the real story isn't that a creek is temporarily closed.

It's that one of Canada's most famous national parks is deliberately undoing decisions made generations ago because we've learned that they caused unintended consequences.

And there may be an important lesson in that for anyone who cares about the outdoors.

Here's Something Surprising About Banff's Mountain Lakes

Look at a clear alpine lake surrounded by mountains and it's easy to imagine trout have always been swimming beneath the surface.

In many cases, they haven't.

Parks Canada cites a survey of 1,464 lakes across Banff, Jasper, Yoho, Waterton Lakes, Mount Revelstoke and Glacier national parks that found more than 95% did not contain fish before stocking began in the twentieth century.

More than 95%.

Some mountain lakes were naturally fishless because waterfalls, steep streams and other natural barriers prevented fish from ever reaching them.

That wasn't considered particularly desirable at the time.

Fishing was becoming an important attraction for visitors to Canada's mountain parks, and fisheries management was largely focused on creating good places to fish.

So humans started helping the fish get there.

Brook trout.

Rainbow trout.

Brown trout.

Yellowstone cutthroat trout.

And others.

Fish were introduced into lakes and streams throughout Banff.

Eventually, the scale became enormous.

Since the early 1900s, nearly 40 million fish were introduced into the Bow watershed within Banff National Park.

Stocking finally stopped in 1988.

But perhaps the best illustration of how differently we once thought about this happened beside a broken-down truck.

The Day 45,000 Trout Got a New Home Because a Truck Broke Down

In 1925, a hatchery truck carrying 45,000 young brown trout broke down just east of Banff.

It was a warm day.

The driver worried the fish wouldn't survive sitting in the truck.

So he did what probably seemed completely reasonable at the time.

He released them into a nearby stream.

The trout survived.

They travelled downstream.

And their descendants eventually became established in the Bow River system.

It sounds almost unbelievable today.

But that's exactly what makes the story interesting.

The driver wasn't trying to harm an ecosystem.

He was trying to save 45,000 fish.

Sometimes good intentions create consequences nobody sees coming.

And those consequences can last much longer than the decision that caused them.

What Happens When You Put Fish Somewhere They Never Lived?

Adding fish to a lake sounds fairly harmless.

After all, they're fish.

They belong in water.

But an ecosystem isn't simply a collection of things that can live in the same place.

It's a network.

Fish eat aquatic insects and other organisms.

Those organisms feed other wildlife.

Different fish compete for food and spawning habitat.

Some introduced species reproduce with closely related native species.

Change one part of the network and the effects can travel through the rest of it.

Parks Canada says historical stocking changed aquatic communities in Banff and contributed to declining native fish populations.

One species particularly affected is the Westslope cutthroat trout.

And it's worth getting to know.

The Trout With a Red Slash Under Its Chin

Westslope cutthroat trout have a distinctive reddish-orange mark underneath their lower jaw.

That's where the name “cutthroat” comes from.

They live in cold, clean streams and lakes and are native to parts of the Bow River watershed.

Today, Alberta's Westslope cutthroat trout population is federally listed as Threatened.

Their decline doesn't have a single cause.

Habitat changes and warming water play a role.

So does competition from introduced fish.

But there's another problem that's harder to see.

Some introduced trout can actually change the genetics of the native population.

Rainbow trout can breed with Westslope cutthroat trout, producing hybrids. Over generations, that can gradually reduce the number of genetically pure native trout remaining in a watershed.

So protecting these fish isn't only about having trout in the water.

It's about protecting the trout that actually evolved to live there.

Which brings us back to Fish Creek.

What Is Happening at Fish Creek?

Fish Creek is part of a much bigger aquatic restoration program that will unfold across Banff over the next decade.

The project includes:

• Fish Creek
• Corral Creek
• Mosquito Creek
• Consolation Lakes
• Upper Babel Creek

Parks Canada plans to remove non-native fish from these waters and reintroduce Westslope cutthroat trout and bull trout in places where they historically occurred.

The goal is ultimately to establish native populations capable of sustaining themselves over the long term.

On August 20, Parks Canada completed the project's environmental assessment and determined that it is not likely to cause significant adverse environmental effects.

Then work began at Fish Creek.

And this is where the restoration story becomes a little more complicated.

To Bring Native Fish Back, Some Fish Have to Be Removed First

The treatment being used at Fish Creek involves rotenone, a substance fisheries managers use to remove fish from a waterbody.

That sentence can understandably sound strange.

We're protecting fish...

by removing fish?

But restoration isn't about maximizing the number of animals in an ecosystem.

It's about restoring the species and ecological relationships that belong there.

And Banff has already been through this process elsewhere.

The story of Hidden Lake shows what that can look like.

At Hidden Lake, Parks Canada Tried the Less Drastic Approach First

Hidden Lake once supported native Westslope cutthroat trout.

Then non-native brook trout became established.

The brook trout competed with the native fish and eventually displaced them from the lake and surrounding streams.

So Parks Canada began trying to remove them.

Starting in 2011, aquatic specialists used methods including:

Angling.

Gill netting.

Electrofishing.

And they kept at it for years.

From 2011 through 2017, crews attempted to eliminate the brook trout using these manual techniques.

They couldn't get them all.

Even a small number of remaining fish could reproduce and rebuild the population.

Eventually Parks Canada used rotenone treatments.

Monitoring afterward showed that the non-native fish had been removed while healthy insect and zooplankton populations remained.

Only then could the next part begin.

Putting the native trout back.

And Then, in 2026, Something Remarkable Happened

Beginning in 2021, Parks Canada started reintroducing Westslope cutthroat trout into the Hidden Lake watershed.

Some began as eggs collected from native populations elsewhere in Banff.

They were fertilized and raised through specially designed incubation programs before being released into Hidden Lake and its tributaries.

Then researchers waited.

Would they survive?

Would the habitat support them?

Would the population actually begin behaving like a wild population again?

This year, they got an answer.

In 2026, reintroduced Westslope cutthroat trout were observed naturally spawning in Hidden Lake for the first time.

Think about what that means.

The success wasn't simply that humans managed to put native fish into the lake.

The success was that the fish started doing the rest themselves.

Finding habitat.

Spawning.

Beginning another generation.

Parks Canada describes the milestone as an important step toward establishing a healthy, self-sustaining population.

After decades of human intervention, one of the ultimate goals is something beautifully simple:

For us to no longer be needed.

Maybe That's What Successful Restoration Actually Looks Like

We tend to imagine environmental action as adding something.

Plant a tree.

Build a habitat.

Release an animal.

Create a protected area.

But restoration can work in the opposite direction.

Sometimes you remove something.

Sometimes you close something.

Sometimes you stop doing something we've done for decades.

And sometimes you return an ecosystem to a point where nature can start doing the work again.

That can be harder.

Because adding something new feels like progress.

Undoing something old requires admitting that the previous approach didn't work the way we hoped.

“We Know Better Now” Is Actually a Powerful Idea

There's an easy way to look at the history of fish stocking in Banff and decide:

How could anyone have thought that was a good idea?

But that's probably the least useful lesson we can take from it.

The people making those decisions worked with the information, priorities and understanding available at the time.

Outdoor recreation mattered.

Fishing mattered.

Ecology wasn't understood the way it is today.

Our understanding changed.

So our behaviour changed.

That's how it should work.

Because sustainability isn't about somehow making perfect decisions forever.

It's about being willing to change when new evidence tells us we should.

There are probably things we're doing in 2026 that someone in 2126 will look back on and wonder about too.

The question is whether we're willing to keep learning.

What Does a Fish Restoration Project in Banff Have to Do With the Rest of Us?

Most of us will never be responsible for restoring an entire watershed.

But we make decisions every time we enter one.

We transport firewood.

We move boats and paddles between lakes.

We fish.

We bring bait.

We walk through sensitive areas.

We interact with wildlife.

We decide whether to respect a closure or go around it because “we'll only be there for a minute.”

And sometimes the consequences aren't immediately visible.

That's probably one of the biggest lessons in Banff's fish story.

Nature doesn't always tell us right away when we've changed something.

Introduced fish can reproduce for generations.

An invasive organism can travel somewhere new on wet equipment.

A shortcut can slowly become an eroded trail.

One harmless-looking decision multiplied thousands of times can become something much bigger.

Which is why being responsible outdoors isn't simply about fixing obvious damage.

Sometimes it's about preventing something we're not going to see until later.

At Chilly Moose, We Think “Stay Out There” Comes With a Responsibility

We want people outside.

Camping.

Fishing.

Paddling.

Hiking.

Exploring Canadian parks.

Watching the sun disappear behind a lake and deciding they're not ready to head inside yet.

Those experiences are a big part of why Chilly Moose exists.

But the landscapes we enjoy can't simply be the backdrop to our adventures.

They need something from us too.

Respect the closures.

Clean your equipment when moving between waterways.

Don't move plants, animals or organisms from one ecosystem to another.

Follow fishing regulations.

Leave the campsite better than you found it.

And be willing to change old habits when we learn there's a better way.

Protecting the outdoors doesn't mean never making a mistake.

It means caring enough to correct one.

What Will Fish Creek Look Like in 2036?

That's perhaps the most interesting part of a 10-year project.

We don't know yet.

There will be years of removal work.

Monitoring.

Native fish reintroductions where appropriate.

Testing.

Setbacks.

Adjustments.

More monitoring.

A tremendous amount of work will probably happen without most visitors to Banff ever seeing it.

And that's okay.

Because if the project succeeds, the best result might eventually look completely ordinary.

Cold water.

A mountain stream.

A native trout moving through it.

No sign telling you how many people worked to put it there.

No explanation of the fish that had to be removed.

No reminder of the millions stocked throughout Banff generations earlier.

Just a species living where it belongs.

Maybe that's one of the most hopeful things about restoration.

The goal isn't to make nature look like we've fixed it.

The goal is to help it reach a point where it doesn't look like we were ever there at all.