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Gunnison River Forecast and Tactics

By admin - Posted on 09 April 2020

by John Duncan, Telluride Angler


In this article, we forecast river conditions for the Black Canyon of the Gunnison and Lower Gunnison River, down to approximately Austin.  


 Gunnison flow forecast

Flows of 530 cfs will likely increase to around 1,000 cfs on May 1 and stay in that range through most of summer.  A short high water release is expected in mid-May, perhaps for only 1 day.  The Curecanti Bureau of Reclamation is notorious for bouncing flows in June, but this seems like a sound prediction given the 90% snowpack of the Gunnison watershed.  A flow forecast update is coming in late April, but initial projections are for the most “normal” fishing flows we’ve seen in 3 years.  Salmonfly hatch should be highly fishable for both floating and wading anglers.  The North Fork of the Gunnison will rise and go off color before May 1 and fall again by late June.




As much as any river in Colorado, Gunnison fishing is hatch-driven.  Food sources are abundant, but Gunnison trout binge-feed during the periods of greatest opportunity.  Hatches are diverse and robust, from giant salmonflies in June to sneaky BWO hatches in the spring and fall.  Here is a partial list we must anticipate in order to capitalize on the best fishing each month.

March-April:  Blue Winged Olives

        Hackle Dun BWO # 20 (photo, right), Mayhem #18-20

Late April-May:  Caddis and remnant BWOs

Para Caddis Emerger #16, LaFontaine’s Caddis Emerger #16

Mid-May through early June:  high water

Mid-June:  Salmonfly stoneflies, giant golden stones

Rogue Foam Stone, Salmonfly, #4-6

Rogue Foam Stone, Giant Golden, #8-10

Pat’s Rubber Legs, black or brown, #6-#10

Late June:  Remnant giant stoneflies, caddis, Yellow Sallies, PMDs

Para Caddis Emerger #16 (photo, right), LaFontaine’s Caddis Emerger #16, Snowshoe Sally #14-#16, Lawson’s No Hackle PMD, #16-#18, Split Case PMD #16-18, Tungsten Sally nymph, #16-#18

Early July:  Yellow Sallies, PMDs, some caddis

Mayhem #16-#18, Split Case PMD #16-18, Tungsten Sally nymph

Mid-July through mid-August:  Tricos, Grasshoppers, caddis (below the N. Fork confluence)

        Morrish’s Foam Hopper #10, best Trico spinner #22, San Juan Worm, Para Caddis Emerger #16

Mid-August-September:  Hoppers, midges

Morrish’s Foam Hopper #10, Kicking Hopper #10-12, Zebra Midge #20-22

Late September-October:  BWOs, midges, a few October Caddis

Hackle Dun BWO #20, Mayhem #18-20, Gunny Special (photo, right), Tequila Bugger


Gunnison Tips and Tactics

1) Things change.  The Black Canyon is technically a tailwater, but it doesn’t fish like one.  Like lower sections of other dam-controlled rivers such as the Deschutes, Missouri and Green, water temperatures vary with weather conditions and flow levels.  Use old-fashion insect observation and fly selection, as you would on a freestone.  Turn over rocks to observe nymph activity, check tall streamside grasses for terrestrials and sniff the breeze.  


2) Riffle magic.  From late June-October, the most intense feeding activity is often found in the Gunnison’s luxurious riffles.  Fish move liberally from deep water to fast riffles and pocketwater to feed during hatches.  They exert more energy in this fast water, but the abundance of food and oxygen makes it highly worthwhile.  When insect activity declines, the fish drop back into deeper water where they can hold with less effort and pick off the occasional drifting insect with a turn of the head.  On most days, big fish will enter the riffles for at least a short period of time.  If you fish a great looking riffle unsuccessfully, try it again in a few hours, or when something notable changes:  increased hatch activity, shade falls over the riffle, it starts raining, stops raining, etc.  Even on our most memorable days, the Gunnison never fishes consistently from dawn to dark.  

3) Work hard when it counts.  Especially in the Black Canyon, afternoon doldrums can exhaust the over-ambitious angler.  If it’s not happening, relax.  Fish slowly.  Take a nap.  Mess with your gear.  Drink a camp beer.  Don’t fight slow fishing.  You’ll need your energy when it turns back on.

4) Close isn’t close enough.  There are two events each year that necessitate casting to within inches of the bank:  the giant salmonfly hatch and hopper season.  

Fish hug the banks during the salmonfly hatch because stoneflies crawl onshore to hatch, rather than emerging through flowing water like caddis, mayflies or midges.  Fish sit on the banks as food marches straight to the dinner table, taking advantage of the shelter provided by rock walls and undercuts in the process.  Same holds for hopper season.  Food is falling out of the grass, so fish sit on the inside edge, under the bank when possible.  It’s a great time to be a trout.  To catch these fish, the angler must cast all the way to the bank.  Experienced float fishers are familiar with casting to the bank as they work the Madison, Yellowstone or Green from a driftboat.  In the Gunnison, we need our flies to fall into the feeding lane closest to shore.  When the current runs along a bank or wall, 12” is too far.  You’ll feel like you made a great cast, but no takers.  Pick up that cast and tuck it 4” off the wall.  The difference is monumental.  Here’s an additional tip:  fish a single dry fly.  You need one fly close to the bank rather than two “in the general area.”  In order to place your hopper or stonefly properly, you can’t have a dropper leader hanging in the grass or otherwise running interference.




5) The right angle.  The Black Canyon beguiles the nymphing angler like few rivers in the world.  Unmatched riffles, bold pocketwater, superstructured banks and mysterious depths demand subsurface exploration.  Accomplished anglers often deploy the “right angle” for precise presentations throughout the water column.  A “right angle” nymph rig involves a discontinuation of your leader’s taper.  Tie your leader’s butt section straight to a strike indicator, then run your tippet off the indicator at a right angle.  Your butt section should be thick and strong, while your tippet should be thin and light, helping your flies fall at a right angle.  This technique allows the angler to precisely estimate fishing depth while eliminating excess leader between the strike indicator and flies, most of which drifts about uselessly, detracting from precision and delaying our ability to observe a take. 


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