The lower Yellowstone River is full of character with long runs, deep pools, bedrock ledges, rocky outcroppings, skinny riffles, and mid-river gravel bars that change throughout the year.
Although trout populations decrease as the river heads East from Livingston, they seem to be just a bit more cooperative and easier to find than the trout that call Paradise Valley home in the summertime. I spend a lot of our time on the lower river - between Springdale and Columbus - immediately following high-water in early summer and then once again starting in early August.
The abundance of “Nocturnal Stones” on the lower river, from late July through mid-September keep the trout active and feeding opportunistically throughout the day during the warm summer months. Early morning hours can be very productive around riprap and in shallow, fast runs while stripping a light-colored Stonefly dry imitation such as a Chubby Chernobyl or Rogue Stone. I have listened to many discussions around Nocturnal Stones and have settled on the best explanation being that they are Golden Stones that are most active at night during the summer months. They become more important to Trout, as a food source, when other aquatic insect activity diminishes in the summer heat.
Grasshoppers begin to congregate near the green growth along the river’s edge during this time as the surrounding fields and grasslands dry out. Their activity is heightened during the warmest periods of the day and many of them end up in the river, getting “washed” downstream when they end up in a fast-moving seam. Once the trout see a few of these, they begin to actively look and feed on them throughout the day. The angler should have Hopper patterns in a wide range of sizes, shapes, and colors as the best ones seem to vary year to year and even day to day. However, once the fish have started to key in on them, the key is to watch closely and change patterns and colors if you see fish reject or not move to your fly.
The "standard” program for fly-fishing the lower Yellowstone River in August and September is to fly-fish with nymphs under a strike indicator in the mornings and then a large dry fly in the afternoons. I typically forego a strike indicator and use a large Chubby Chernobyl in a size 10 with a 3’ length of tippet, tied to a size 10 Tan and Brown Pat’s Rubberleg and off the bend of the hook of the dry. While occasional takes on the dry are common, most of the action is usually on the dropper in the mornings or on cloudy days. When the sun gets up overhead, that’s my cue to put on a single dry (Hopper pattern) and start focusing my attention on gravel bar ledges and mid-river seams where trout actively hold to feed on passing natural insects of all kinds.
I have been out there a lot in 2023 and it has just started to “get” good as the summer heat has settled in as of early August. Whether you are floating the lower Yellowstone on your own or would like to go out with one of our Bozeman fly-fishing guides, mid-August is a great time to be on the river in 2023. E-mail us if you would like more information about a guided fly-fishing trip on the lower Yellowstone River or simply click on one of the links throughout or site to book online.
