The Magic Half-Inch

By: Chester Allen

Fly Fishing Crooked River

photo by Brett Bunch

The Half-Inch Zone

One of the great — and maddening — things about fly fishing is that the solution for almost every angling problem is right out there, hiding in plain sight.

Trout make me crazy all the time. Sometimes they’re rising, and I can’t find the right fly. Sometimes they ignore what I think is the right fly. Sometimes they ignore everything.

But, every now and then, I figure it out — at least partially. Sometimes I hit the solution pretty quickly. Sometimes the answer hits me on the drive home. Sometimes the light dawns a couple years later.

I tend to puzzle things out when I’m not staring at big rising trout and frantically changing flies every couple of casts. These days, I try — and sometimes fail — to look at other things besides the fish.

I fish a lot of backeddies on my Northwest rivers, especially in the fall and winter. If it’s a cloudy or rainy day, my local trout usually tip and sip blue wing olive mayflies in the afternoon. This happens often enough that I carry an entire fly box crammed with blue wing olive emergers, duns and spinners.

But there are times when the hatch doesn’t come off — even on cloudy, humid days.

Yet, I suspected these backeddy trout were eating something. You’ve seen those kind of days, when there is a rise here, and another rise a few minutes later over there, but the trout never start eating in any kind of pattern — and there are very few bugs on the surface.

Hints in Plain Sight

On those days, I often opened my nymph box. I’d tie on a blue wing olive nymph — say a Pheasant Tail or Copper John — and start fishing deeper water that feeds into the eddies. I often caught some tiddlers — but nothing of any size.

At the same time, I often found blue wing olive nymphs swimming around in the quiet water near the bank. These nymphs look like tiny minnows. There were lots of them, but I never saw many risers.

Something had happened, but what?

I got a huge clue when I was rereading my friend Dave Hughes’s great book, “Wet Flies,” where he goes into some detail about fishing wet flies and soft hackles just under the surface before and after mayfly hatches. I then immediately dove into another one of Hughes’s books —“Pocketguide to Western Hatches” — where I found his words about fishing nymphs just under the surface during a Blue Wing Olive hatch.

Then I remembered another friend, Craig Matthews of Blue Ribbon Flies in West Yellowstone, Montana, talking about fishing tiny soft hackles during a BWO hatch.

Hello, Eddy

Luckily, all these clues collided in my brain on a blustery fall afternoon last year on Oregon’s Deschutes River. I was standing on the banks of a favorite eddy watching tumbleweeds blow into the water. It was cloudy enough for those tiny mayflies to hatch, but I couldn’t see any winged insects sailing on the rough, wind-blown water.

I saw a rise every now and then — and some very subtle swirls on the wind-blown surface. I couldn’t tell whether the swirls were fish or the wind. I reached for my 6X tippet and box of tiny nymphs without really thinking.

I had the notion of casting a tiny, size 20, unweighted Pheasant Tail nymph onto a four-foot-long tippet of 6X — and then letting the fly drift through the swirling eddy. I figured that the trout were probably looking for nymphs near the surface — or at least wanted to see nymphs near the surface.

I made a few casts, and mended the line so the fly drifted into the current seams and foam lines. Six or seven casts later, I hadn’t gotten a bite. I didn’t have any brighter ideas, so I keep casting.

A few casts later, the tip of my fly line jumped forward. I lifted the rod, and a wild rainbow trout flipped into the air. A few casts later found another trout on the line.

Encouraged, I shortened my casts a little and keep a close eye on my line. I noticed that most of my strikes happened when the current was dragging the fly just a little bit. I suspect the fish are used to seeing BWO nymphs swimming or emerging just under the surface.

I also noticed that those subtle swirls — not a rise and not a boil — were trout feeding on my nymph just under the surface.

Since that afternoon, I’ve spent quite a bit of time fishing backeddies on three of my local rivers. All of these rivers see a lot of fishing pressure, and the trout are very, very picky when it comes to dry flies. Dries have to be the perfect size — and should usually imitate a crippled adult. Sparkle Duns work well.

At the same time, these same trout — in three different rivers — are much less picky about nymphs and tiny soft hackles drifting around an inch or so under the surface.

I’ve also had some success drifting tiny nymphs and soft hackles to rising trout in very slow, weedy runs. I really believe that many of my local trout have learned that it is safer to eat nymphs in that magic half inch of water below the surface.

Constant Change

Fishing the Magic Half Inch suddenly became a big part of my bag of tricks. It’s worked often enough during the past year to make my ego swell up — and my brain to shrink.

About two weeks ago, I arrived at Oregon’s Crooked River as storm clouds massed over the desert stream. A gentle breeze blew, and Redside rainbows rose in a favorite backeddy a couple miles downstream of Bowman Dam. Hundreds of tiny BWO duns rode the currents.

I automatically tied on a size 20 Sparkle Dun. No bites. Then I tried the excellent Almost There Baetis. No bites. Then I tried the tiny Pheasant Tail on the long, 6X tippet. No bites — but even more risers, some of them really big. A nice rainbow trout looks like a big steelhead when it does a head-and-tail rise in slow, swirling eddy water.

Of course, my ego exploded — and so did all of my angling skills.

I just about beat the water to a froth for about an hour. Why weren’t these fish eating the flies that were hatching EVERYWHERE? I tried a Baetis Foam Emerger. I tried a Blue Wing Olive hackle spinner. I tried the Baetis Cripple Black Wing. I tried other small nymphs. I tried midge patterns. I tried so many flies and caught zero fish.

It’s always a bad sign to change fly after fly.

Taking Another, Longer Look

Exhausted, I sat on a bankside rock and gazed at my fly boxes. No answers there. Then a bug landed on my glasses. It looked huge. I took off my glasses and found a Mahogany dun mayfly in about size 16 or so.

I thought for a minute or so — and then gazed at the eddy for about 10 minutes. Every now and then, a Mahogany dun rode the river downstream into the eddy — and then surfed the circular, swirling currents amid hundreds of smaller BWO mayflies. Those mahoganies looked giant next to the smaller mayflies. I realized that I hadn’t even noticed the larger mayflies during my maniac focus on the smaller, more-numerous bugs.

A couple Mahogany duns vanished in rises, but most didn’t. I watched and thought for a couple more minutes. I tied on a size 16 Pheasant Tail nymph onto a long tippet. I cast it out into the swirling eddy — and broke off a nice trout on the first cast.

The Magic Half Inch is real, but you’re gotta have the right fly, in the right size. You also have to see what is going on right in front of you.