Seasons of the Bighorn

Seasons of the Bighorn

August 31, 2011 3:13 pm Published by Leave your thoughts

Seasons of the Bighorn River – Bighorn River Trout Fishing


The Bighorn River is a classic tailwater river, emerging from the depths of Bighorn Lake in Eastern Montana.  The Yellowtail Dam, in Fort Smith, MT, has created a fertile river, displaying unique spring creek characteristics that allow Rainbow and Brown trout to thrive year round.  There is somewhere around 5,000 fish per mile in the Bighorn, with the numbers being higher the closer you are to the Afterbay dam.  Trout in the river average around 15 inches, with many fish pushing the 20 inch range.  Bighorn river trout fight as hard as any trout on the planet, due to the highly consistent water temperatures year round.

Below Afterbay Dam the fishing stays productive for about 30 river miles.  The Bighorn is broken up into three distinct sections: Afterbay to 3 Mile, 3  Mile to Bighorn Access, and Bighorn Access to Mallard’s landing.  Each section contains variances in water temperature, fish per mile, aquatic life, hatches, and fish behavior.  These characteristics create unique fishing conditions in which the fly fisher can have a wide array of terrific fishing throughout the year.  Throughout the river’s length, rainbows and brown trout thrive on a steady diet of Sowbugs, Scuds, Worms and Midges year round which accounts for the large average size of the fish in the river.

Spring – March – May

The spring seasons runs from March thru May. Early spring is often a very overlooked time of the year, especially for traveling anglers. While air temperatures in early spring can range from around freezing to the high 60’s, the water temperatures hovers around 35 – 43 degrees Fahrenheit and is conducive to excellent hatches of midges and Blue Winged Olives.  During this time browns are trying to fatten up after the fall spawn and a long winter and the rainbows are consuming energy in preparation for their stressful mating season. Streamer and nymph fishing throughout this time of year tends to be very consistent, fished slow and deep.    Please Note: It is highly unethical and damaging to the fish to target them during the spawn.  Try to stay away from light colored gravel and dark bodied fish, especially in side channels.

Midge hatches can occur throughout the day in various sizes and colors, so carry an assortment of flies.  Fish larval and pupal patterns in slower runs until you begin to see rising fish.  You will begin to see noses and snouts popping up for the duns or head and tail rises to the emergers.  Fish eating midges tend to pod up.  Scout the prime water until the frenzy begins.

Blue winged olives are one of the most prolific hatches throughout the country.  However, if you haven’t experienced a BWO hatch on the ‘Horn you have been missing out.  The magic water temperature that really seems to get this emergence going is between 42 and 45 degrees. The hatch during a typical day can last anywhere from one hour to eight depending on its intensity.  For more information on the BWO hatch visit our Blue Winged Olive Page. By the end of spring runoff has typically begun when snowpack levels in the mountains are high.  The upper river always stays clear and fishable except during very rare intense periods of rain.  However smaller creeks running into the lower river can muddy up the river and create difficult fishing conditions or make it not worth your time.

Summer – June – September

The summer season runs from June to September.  Once runoff subsides the river is in full swing and hitting on all cylinders.  Pick your style of fishing they can all be good.  The water temperatures warm up to a prime comfort level for the trout and are optimum for the summer hatches of Mayflies and Caddis.  During the summer surface action is dominated by Black Caddis, Grasshoppers and Terrestrials.  With a mix of PMD’s, tan caddis and trico’s making an appearance when conditions see fit. Grasshopper fishing typically begins in July and the intensity of hoppers along the river is typically cyclic depending on the year. As water temperatures increase the trout move from their cold temperature deep slow water to fast, well-oxygenated riffles, especially when the river bottom begins to be over taken by aquatic vegetation.  Adjust your tactics accordingly and sub-surface fishing with nymphs, emergers and soft hackles in the riffles can be great.

Fall – September – November

The leaves begin to change, snow falls on the mountains, water temperatures begin to decrease and big browns go on the prowl. Fall fishing runs from September through November for me is time to break out the hard hats, rig up a sink tip and dredge up some big browns and rainbows with streamers.  When streamer fishing is on, it can be legendary on the Bighorn. On the surface Black caddis persist into September and during Indian summers so does the grasshopper fishing.  Emergences of Pseudocleons, BWO’s and Midges tend to rule the day.  If you are so lucky you may run into the elusive Mahogany emergence as well.  By this time of the year I tend to shy away from the bobber and double nymph rig unless conditions require us to do so. Nymphing however can still be very productive throughout the fall as rainbows transition back to winter lies and Browns stage for the spawn.

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This post was written by Bighornangler

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