If there was a time of year that strikes despair and fear into any anglers heart it would be fishing rivers at their high water or runoff stage. A perception of doom and gloom can occur in such a time, but often opportunities to fish during runoff exist...just a little extra effort might be in order. The reality is that there is some truly exceptional fishing to be had during runoff season on Montana's large freestone rivers that become high and off color as the snow melt accelerates.
Montana river flows peak during "run-off" in late May and early June when snow melt is at its peak. While fishing lakes, spring creeks and tail waters below dams are always a great option during runoff, don't discount the off color freestone rivers. Most anglers associate run-off season fishing with sticking to lakes, tailwater fisheries below reservoirs such as the Missouri and Madison, or spring creeks. While waters that are protected from run-off are certainly a great option in late May and early June, there are still options on rivers that lack protection from dams. Waters that have streamflows that are not controlled by dams are called freestones.
High water does present an interesting and intimidating set of conditions on Montana freestone rivers. On some fisheries like the Yellowstone River and Gallatin Rivers, the highest flows become unfishable during run-off. On other Montana rivers the higher flows can actually enhance a day of fishing, and provide the best angling of the year! High flows can also provide the best chance to target trout of Herculean proportions.
Where to find trout during runoff
Fishing rivers at their highest flows produces the added benefit of concentrating trout. Trout prefer to conserve energy during higher water and seek refuge in areas with slower flows. Most trout find refuge along the banks as the river rages full with current. Because of this notable diaspora to the banks, finding fish isn’t the crux of the day. When flows are high, even trout are forced from mid river haunts and assume the prime lies along the bank. Major rock structures also provide further shelter and the seams behind these formations can be productive. A final holding location that often produces higher trout concentrations are the inside bends of rivers; as large swollen rivers enter into turns the strong current pushes to the outside of the bend, leaving trout-rich slower currents on the inside of the turn.
Know how much visibility is needed for good fishing
Just because a river looks brown doesn't mean the fishing is poor. Keep in mind that trout are highly concentrated along banks, behind rocks and on inside corners at higher flows. Generally you only need about 6" of visibility for good fishing as long as you can target trout effectively. A good rule of thumb is that once the increased sediment load in a river produces visibility less than 2 feet in depth the river will take-on a brown look to it. As clarity increases between 2-4 feet it will have a "green" look. Some rivers such as the Yellowstone River which has a lot of loose volcanic ash deposits in its drainage will dirty easily as the river rises and produce clarity so poor that fishing is very difficult. Numerous other rivers, however will fish well even at the highest flows. The Smith River for example rarely looks "clear" in the spring floating season but it almost always has at least 6" of visibility and will fish exceptionally well when off-color as long as flows are stable.
Nymph fishing at high flows
In the weeks preceding marginal water clarity, the fish receive almost no angling pressure on most of Montana's freestone rivers. Unpressured fish are most amenable to fly presentations, and catch rates can be quite high despite the stained water conditions. The stained water also provides security to trout, further heightening the bite and allowing them to slide in shallow lies or lies along bankside structure. High flows also serve as a purging system moving sediment and other nutrients throughout the watershed. Droves of aquatic insects are also dislodged at this time, and the subsidence of runoff also coincides with the migration of large stonefly nymphs to the banks. This movement of insects only heightens the trout’s fervor to feed.
Nymph fishing can be exceptionally productive during this season of higher flows. Anglers need to focus on larger flies on short leaders. With off color water, small nymphs are harder to spot in the swift currents. Trout are keying in on larger food sources and you can increase your catch rates by choosing flies larger than you might normally choose. Large dark colored rubber legged stonefly nymphs are a Montana fly fishing favorite during runoff. Another effective nymphing strategy is to fish single hook streamers such as Zonkers as a nymph. A two fly rig can also increase results. Try trailing a worm pattern behind your stonefly or Zonker.
Targeting the banks can prove to be frustrating using traditional pre-packaged tapered leaders which are too long. Even 7.5 foot leaders can be too long to turn over heavy nymph rigs resulting in lower accuracy. Accuracy counts when fishing the banks and the closer you can get your flies to the edge the better. Longer leaders tend to also swing the flies out of the strike zone and into the faster main current more easily. When float fishing during runoff your leader should be ultra short, no longer than 5 feet. Many of our Montana fly fishing guides prefer to run Maxima to the fly line where the indicator is rigged and then transition to heavy tippet using a tippet ring or small swivel. The tippet ring can also help serve as stop for your split shot. You can also try running just straight level tippet to your flies. When fishing the banks the trout are generally not that deep but you still want to use some weighted flies and split shot to get the bugs down 2-3 feet quickly in the fast current. Make sure to use stout tippet to help reduce breaking flies, 0X,1X, and 2X tippets are the norm. Flourocarbon tippet is a nice option this time of year as well. Although flourocarbon is touted as being less visible in clear water; its other characteristic of being more abrasion resistant is even more desirable during runoff when flies are routinely cast along banks and brush.
Streamer fishing
Anglers seeking big fish in Montana with streamers are big fans of runoff season. As previously mentioned, high water forces larger fish to vacate center river lies in favor of the bank. Perhaps the hardest part of big fish angling is to consistently find large fish. Generally when hunting these big fish its best to fish on the lower light levels of the day such as dawn and dusk. Cloudy and overcast days can also produce great streamer fishing throughout the day. The major concern with high water streamer fishing is color selection. There are a few intricacies to color selection primarily related to lighting conditions and water color. For dark conditions, black serves as a good starting point but any darker pattern can provide a nice option in murky waters or on an over cast day.
Although we tend to prefer throwing streamers under low light levels, there are days where trout are chasing under high sun. When fishing on sunny days try lighter streamers such as white, tan, or tinsel based such as a Sparkle Minnow. The fly size range can vary somewhat, but for truly large fish its best to start in the 4-inch range and work up. These flies can be single hook or articulated depending on personal preference. Sparkle Minnows, Home Invaders, Sex Dungeons, and their variants all perform well.
When fishing bankside structure from a boat during high water, use a floating line and a very short leader. Floating lines are important since you don't want to retrieve the fly more than a few feet off of the bank before you recast. Sink tips and sinking lines require you to retrieve most of your line before recasting. Floating lines are also the best option when streamer fishing smaller meadow streams, again the fish will be tight to the banks and you are generally fishing across the current to the opposite bank, making a few strips and then recasting.
Summary
While many anglers dismiss Montana freestone rivers and creeks during runoff and flock to spring creeks and tailwaters during runoff, off-color and high rivers and creeks can fish quite well. In fact many of the freestone rivers are nearly devoid of competing anglers during snowmelt runoff.
If you are in search of solitude and big fish don't give up on your favorite freestone rivers. Brown and off-color water has its benefits and tends to scare off the faint of heart. Give high water fishing a shot and you might be pleasantly surprised!