First Real Cold Snap – Anchor Ice Forms on the Bighill Creek

Every fall of the year, during the first really cold weather, anchor ice forms on the bottom of the stream channel of BigHill Creek. This happens when the water temperature drops below zero Celcius. Ice clusters which are floating suspended in the water, start to attach to the stream bottom, both rocks and weeds are anchors for the normally buoyant ice.

Anchor ice on the streambed of Bighill Creek, in October.

The slushy snow like anchor ice will disappear once the cold surface water is warmed by the weather or insulated by a covering of ice and snow on the surface of the creek. Even the influence of ground springs can prevent this anchor ice from happening or help in its fast removal. Resident stream fish, like trout, find refuge in deep pools, runs and beaver dams when the anchor ice forms. Invertebrates find protection under rocks or debris and they are safe from the anchor ice.

This is a natural occurrence on spring creeks, further down the system, where the water temperature is cooling from its source temperature. On some creeks, the resident trout will seek winter refuge in larger streams further down a system or at the mouth of a larger stream. Beaver dams play an important role in maintaining a resident trout population.

The bottom line is that the appearance of anchor ice is usually brief and it occurs in the fall of the year. I know that one particular mink that likes to frequent the lower reach of the Bighill Creek, is probably safe in its den when the anchor ice appears suddenly.

I’m Still Fly Tying a Particular Nymph Pattern.

After tying dozens of bead head nymph fly patterns, I finally got the chance to work on some simple old fashion trout flies. I’m still tying nymphs but without a bead, just plain Mayfly style, Crisscross nymphs. There are plenty of good applications for an unweighted mayfly pattern. You can fish them dry or just sub-surface. Strip them in long, short or slow pulls. All of this happens near the surface of the water, so trout will come up for them in aggressive strikes.

This Crisscross nymph is a great sub-surface trout fly

The fly is tied with a yellow teal flank feather fibres for the tail. The wing case can be either a secondary pheasant tail or bleached goose wing quill. The legs are from an Indian Hen saddle hackle. The legs are more durable than soft hackle, so this makes this nymph a tough, durable trout fly. The brown color pattern is deadly and one of my favorites. I tie this pattern on mainly size 14 – 2x nymph fly hooks. With bent down barbs. The ribbing is Mylar, pearl or similar, and copper wire cross wrapped on the abdomen. Thus the name, Crisscross nymph.

About Guy Woods

I am Director of Bow Valley Habitat Development, based in the Town of Cochrane, Alberta, Canada. I love to fly fish and it is this past time that prompted me to get involved in the field of riparian and fish habitat enhancement. I have been working in this pursuit for over 40 years!
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