The salmonfly hatch in Colorado draws a wide range of opinions among anglers, from “epic” to “overrated.” Some might tell you it’s a highlight of the year. Others might advise that it happens during runoff and that it’s hardly worth the effort.

Whether you find the hatch thrilling, disappointing, or somewhere in between, may largely depend on your expectations. But there are a few things every angler should know about fishing the salmonfly hatch in Colorado and how to make the most of it. 

The Bugs

In order to make the most of the annual hatch, it really helps to know something about salmonflies themselves. And reciting their Latin name is not one of them.

Perhaps the most important thing you can remember is that the adult salmonflies you’re hoping to see crushed by hungry trout, are already four years old. Salmonflies live in a four-year brood cycle. Those big, gangly adult bugs have spent three years as nymphs, crawling along the riverbed and hiding under rocks. 

That’s important for anglers, because it means that salmonfly nymphs are a year-round food source for trout. It also means there are three different sizes (age classes) of nymphs lurking in the river substrate. And around their fourth birthday, the oldest and largest of those nymphs will begin crawling their way toward the banks in order to complete their metamorphosis. 

This mass migration usually begins in May, and the hatch typically occurs sometime between late May and early June, depending on the location and conditions.

Upon reaching the bank, these nymphs will attach themselves to rocks or foliage, and then break free from their husks and emerge as adult salmonflies. From there, they will mate. And finally, the females will clumsily fly over the water to deposit their egg sacs in order for a new brood to begin.

The Fishing

Anglers who pay attention can catch fish on salmonfly patterns well outside that elusive “peak hatch”. 

On rivers that support salmonflies, a big stonefly nymph can be a great searching pattern any time of year. Because these bugs live for three years under the surface, it’s easy to assume that many of them end up as trout food, long before they reach adulthood. 

In Colorado, the most well-known salmonfly hatches occur on the Gunnison River, the Colorado River, and the Rio Grande. But salmonflies can be found on many cold, clean, oxygenated streams. Hatches also occur on rivers like the North Platte, the Roaring Fork and more. And don’t forget about the tributaries. On mainstem rivers like the Colorado with abundant salmonflies, these bugs will often work their way well up into smaller tributaries. It’s never a bad idea to explore some of these lesser-known waters with a salmonfly rig.

In the days and weeks leading up to this year’s brood emergence, those largest nymphs will be crawling their way toward the banks. This makes them more vulnerable to being swept away and becoming trout food. This means excellent nymphing with big bugs like a Pat’s Rubberlegs.

When the adults finally emerge, this will often coincide with runoff. High and off-color water can make conditions challenging. But remember that during high water, many fish will be holding close to the banks and along the outside edges of the river anyway. This is also where drowned adult salmonflies can make an easy meal.

After they’ve mated, the female salmonflies will deposit their egg sacs onto the water. They are clumsy fliers, and many of them end up in the river. This is when some of the best dry fly fishing happens. 

However, consider that days before and days after the “big” hatch, residual bugs may be doing their business around the river. During these times when the trout are not completely gorged, they may be more willing to opportunistically take down a big meal. 

Rigging and Tackle for the Salmonfly Hatch

We asked the Anglers All crew for their salmonfly fishing tips. First, Rachel had some great advice. 

“My favorite setup is a 6-weight fly rod with a punchy fly line like the Rio Bank Robber and a shorter leader,” Rachel told us. “My preference would be to cut down a 7.5-foot, 3x leader to about 6 feet, or where the leader is about 1x or 2x. I prefer to shorten it to eliminate the twisting of the leader with the big bug flopping in the wind. 

“I also use a non-slip loop knot on my bigger dry flies to allow them to move more freely,” Rachel added. “If I'm catching the overall hatch early and there are plenty of rises, I'll fish just a single dry. If the fish aren't rising or the water clarity is really off, I'll use a hopper-dropper rig with an orange and black Pat's Rubberlegs, a bead head leech, or a prince nymph under a big salmon fly dry.” 

Rachel says that she carries High N Dry Paste floatant and tons of flies, as the fish tend to tear apart the foam flies during this particular hatch. Finally, she reminded us to bring a Buff if you don't want them crawling on your neck!

Next, we asked Blake for his approach to fishing salmonflies. 

“Gotta go with a 6-weight fly rod for these big bugs,” Blake said. “Otherwise, you will wear yourself out casting all day long. My favorite new 6-weight is the Winston Air 2 Max. It’s powerful, but still gives you enough feel for dry fly fishing. 

“A punchy line like the Scientific Anglers Infinity Taper or the Anadro are both great options in a fly line that can handle big flies. Both tapers can turn over dries and do it with great accuracy. One of my favorite salmonfly patterns is McPhail's Salmon Fly. It sits low in the water, and when there are a lot of bugs hitting the water and skittering everywhere, I think this looks like a drowned salmon fly and maybe an easier target for feeding trout.” 

Blake added that you might often see the bushes covered with adult salmon flies, but no rises. He said to be patient and wait. “As the day warms just a few degrees, you'll finally see bugs flying and starting to hit the water to lay eggs. Then it is on!”

Ben Kinne chimed in as well with a great tip. “I always pack a sharpie in my bag during the salmonfly hatch. I find many of the dry fly pattens in the bins to be too orange, and coloring them up riverside can make the difference”. 

Finally, Jimmy chimed in with some words of wisdom.

“My go-to pattern during the salmonfly hatch is a red Chubby Chernobyl in size 10,” he told us. “I treat it with High N Dry liquid floatant. If the water is high, look for soft spots where fish can be holding tight to the bank. Places where overhanging willows might be crawling with bugs are perfect targets. Don’t worry about being delicate with your presentation. A big splat on the water can often grab the attention of a fish.”

Please Contact Us With Questions

If you have questions about salmonfly patterns, gear, rigging, or how to make the most of it this season, please reach out. You can stop by and see us at one of our fly shop locations in Littleton or Denver. If you can’t make it to the store, give us a call at 303-794-1104. And remember that we offer fast, free shipping on all orders over $10 here on the website.