Of all the small rivers and hidden gems in Montana, the Stillwater River provides some of the best fly fishing opportunities in some of the most beautiful scenery one could hope to find.
It is also one of the most inappropriately named rivers, as more than half of the length of the Stillwater is made up of whitewater and rapid flows.
This means that it can present problems for those looking to float the river, but there are calmer stretches where this is possible, and there are great opportunities to wade in all along its 70 mile length.
Depending upon which section of the river you fish and what time of year you choose to go, you will have opportunities to catch rainbow, brook, cutthroat and brown trout in the Stillwater. It has large populations of each and is very lightly fished, meaning many of the fish are eager to jump at the first fly they are presented.
It then winds its way down through the mountains, beyond the mountains and the wilderness before entering a 45-mile stretch of prairie and canyons where the water slows and the river is more accessible. The river then winds it way through this land of majestic prairies before spilling into the Yellowstone River near the town of Columbus, Montana.
There are many opportunities for great fishing all along the river, and for such a short river, it offers a great variety of landscapes and many varieties of fish. There are also multiple fly hatches beginning in early spring and lasting all the way into the fall that provide for excellent fishing.
Springtime is usually the best time if you are looking to catch a lot of fish, but the water stays relatively cool even through July and August. Fishing is still relatively good in many parts of the river all the way through September, and this is often the best time to catch the larger fish as they travel from the Yellowstone for spawning season.
The first 20-mile section of the Stillwater River flows between towering mountains in the Absaroka-Beartooth Wilderness. This is a wild area of untamed beauty, and the rapid flowing whitewater along much of this stretch seems to reflect that perfectly.
Because of the whitewater stretches, pocked with rocks and separated by several low bridges, it is usually not recommended to float this area. However, this also means that the pools along this stretch provide refuge for a nearly unlimited number of brook, cutthroat, rainbow and brown trout that can be easily caught by a wading angler of any skill level.
There are many great access points along this stretch, although a hike or ride may be required to reach the river through the wilderness. One great slow moving slough along before the river leaves the wilderness is the Lake Sioux Charley where there are some great opportunities.
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As the river leaves the wilderness, the flow slows down and winds next to the town of Nye. This area is characterized by amazingly clear water, few rapids and lots of pocket water.
The 45-mile stretch beyond the wilderness and past the town of Nye is usually the best area for catching browns and rainbows in very large numbers. Although it can still be treacherous in some areas, float fishing is much more easily done through this stretch.
Towards the end of this stretch, the water becomes muddier as it receives flow from the Rosebud river, and a large amount of silt with it. Rainbows and browns become even more numerous and the pace of the river begins to increase again as it concludes its journey and flows into the Yellowstone River near Columbus, Montana.
This little river has some level of great fishing available through just about all of the year.
However, because of its slightly temperamental disposition and the rapids caused by varying water levels, the type of fishing you are able to do will depend largely upon the time of year.
Especially in the upper parts of the river where it runs through the mountains, floating can be very difficult during the summer, but there are plenty of great spots to wade in at any time.
Because of the numerous hatches, spring is probably the best time of the year to catch a variety of trout with dry flies. This trend continues through much of summer, and the water remains relatively cool, even in July and August.
September also presents great opportunities (especially with hoppers), as the trout from the Yellowstone River migrate for spawning season.
Sunday 12/16 0%
Partly cloudy. High 48F. Winds SW at 10 to 20 mph.
Monday 12/17 10%
Mainly cloudy. High 46F. Winds SW at 15 to 25 mph.
Tuesday 12/18 20%
Partly to mostly cloudy and windy. High 41F. Winds SW at 25 to 35 mph.
Wednesday 12/19 20%
Windy with a few clouds from time to time. High 39F. Winds W at 25 to 35 mph. Winds could occasionally gust over 40 mph.
Thursday 12/20 0%
Mostly cloudy skies. High 43F. Winds SW at 10 to 20 mph.
Virtually any dry fly or attractor will work great for the first section of the river within the Absaroka-Beartooth Wilderness. Fish in this section are often smaller than in the calmer regions, but they are not picky about what they jump at.
Streamers and large nymphs are ideal for the large brown trout population, while rainbows and cutthroat can be caught with standard dry fly and attractor patterns. Hoppers and caddis will have more success as the weather gets warmer.
Aside from flies, it is also a good idea to bring a sturdy pair of felt wading shoes, as the bottom of this river is exceptionally rocky.
Montana Troutfitter provides recommendations for a variety of flies that are effective on the Stillwater River.
Griffiths Gnat: 16-18-20
Low Rider Midge: 18-20-22
Brooks Sprout Black: 18-20-22
Micro Midge Black/ Red: 18-20
Soft hackle Pheasant Tail: 16-18-20
Mega Hare's Ear: 6-8
Mega Pheasant Tail: 6
Mega Prince: 4-6-8
Mr Rubberlegs Brown Stone: 6-8
Copper John Yellow, Blue, Red, Lime: 12-14-16
Lightning Bug Pearl, Gold, Silver: 14-16-18
Purple Berger: 14-16
Crystal PT Pearl, Rust: 14-16-18
Wire Worm: 6
Sparkle Minnow and articulated Sparkle Minnow; JJ colors (brown/yellow)
JJ Specials Black
Olive Sex Dungeon: 2
Black Home invader: 2 Black
Olive Dolly Llama: 2 CH
Bow River Bugger Black, Brown: 2-4-6
Stinger Sculpin Tan, Olive: 4
Silvey's Sculpin Black, Olive, Tan: 2
Flash Fry Whitefish: 2
Bling Minnow Pearl & Gold: 4
Baby Gonga: 8
A 9-foot 5-wt fly rod with floating line is perfect for fishing dry flies and small nymphs on the Stillwater River. For larger nymphs and streamers a 9-foot 6-wt with a sink tip fly line makes life easier. A tapered 9-foot leader, with tippet size 3X to 6X to match the flies you are throwing, is pretty standard.
There are a number of area fly shops that publish Stillwater River fishing reports. A few to check out include:
Whether you are looking for large fish or large quantities; whitewater wilderness or steady streams; brook, rainbow, brown or cutthroat, the Stillwater is anything but still, and it has something to offer for any angler.
Looking for more places to fish in Montana? Check out our DIY Guide to the Best Fly Fishing in Montana.
Ken is an avid fisherman of 40+ years who loves to explore and is on a quest to map the best places for fly fishing in America. He created the DIY Fly Fishing App to share this information and help you find new places to fish.
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