How to Fly Fish Glacial Runoff?

posted in: Europe, Fishing, Fly Fishing, Switzerland, Travel | 0

Glacial runoff is an occurrence faced by fly anglers in mountainous regions. How to deal with it?

Swiss Alps Fly Fishing

Having organised two fly fishing guiding weekends in the Swiss Alps, André and I had to cope more frequently with glacial runoff. As a fisherman fond of clear mountain streams, this was a daunting task at first. If I had been fishing by myself, I might have just relocated to clear waters. Given that many creeks in the Swiss Alps are fed by glaciers, it was necessary to get accustomed to this precondition. So here is what I have learnt and some advice on how to fish glacial run-off.

Glacial Runoff in Switzerland

Depending on the precipitation in winter and temperatures in summer, glacial runoff starts at the end of June or July. From then onwards, creeks and rivers alike are prone to carry silt. This fine sediment is caused by glaciers wearing down the stone to dust. The sediment causes the river to appear in a murky blueish-grey colour. Depending on the strength of the runoff this teint varies.

River coloured by glacial runoff
River coloured by glacial runoff

How to Tackle Glacial Runoff

Here are tipps on how to deal with glacial runoff. In order to succed, it is crucial to know about fish behaviour in coloured water. Nonetheless, one can still enjoy a great fishing trip, regardless of not seing the fish yourself. Trout have much better visibility in the water during runoff, than us who look into the water.

Try Early

Due to the fact that glacial runoff varies according to the temperature, it oscillates in strength throughout the day. Therefore, rivers are less affected by silt in the morning when it is colder. Hence, as a rule of thumb, anglers are advised to better head out sooner than later. In this way, you avoid the peak of murkiness in the afternoon.

Dry fly fishing in a coloured river by glacial runoff
Dry fly fishing in a coloured river by glacial runoff

Fish Deep

Coloured water pushes fish to the bottom of the river. Trout usually like to sit behind or in front larger structures, where they are protected from the current. Because of the reduced visibility, it is of utmost importance to get the fly down to eye level. Therefore, a heavy point nymph is required to get down fast. Pay also close attention to mending when fishing nymphs with an indicator rig.

Heavy jig nymph for fishing deep
Heavy jig nymph for fishing deep

Cover the Riverbank

Trout, which generally inhabit those cold mountain streams, prefer to stay close to the riverbank. Avoiding the main current, fish love eddies and other back currents. Two positive side effects enhance this behaviour. On the one hand, it allows them to rest and avoid the main current. On the other hand, the closer the fish is to the riverbank, the shallower the water is. Thus, allowing the fish to see through the entire water column, which in turn facillitates locating food on the surface. This brings us to the next point.

Focus on the spots close to the riverbank
Focus on the spots close to the riverbank

Try Dry Flies

For me personally, dry fly fishing was exclusively reserved for clear mountain streams for much too long. Having fished many turbid waters this year, I found trout to be very fond of floating insects. Albeit the visibility is drastically reduced, they are eager to feast on dry flies as soon as they locate them. Black emerger patterns or the Royal Wolff in #10-14 are patterns that have proven very successful. Furthermore, those flies are easily visible to the angler with the blueish-grey backdrop of the glacial runoff.

Royal Wulff Dry Fly

Don’t Be Afraid of Fishing Glacial Runoff

Facing spring runoff, anglers should try early, fish deep and cover the riverbanks thoroughly.

Arriving at a coloured mountain stream puts off many anglers. This should not be the case, unless the water is truly blown out by a flood, in which case anglers should remain away for their own savety. Trout have to deal with murky water for several months every year and so do we. Facing spring runoff, anglers should try early, fish deep and cover the riverbank thoroughly. Moreover, dry flies should not be neglected because trout can see better through cloudy water than anglers can see into it.

In a nutshell, do not let turbid glacier water discourage you from fishing, because trout are less worried than we are.

Rewarding catch caught on a dry fly during runoff
Rewarding catch caught on a dry fly during runoff


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