The Jefferson River fishing is best reserved for the early morning hours throughout most of August.
Low flows are exasperated by heavy, upstream irrigation demands as well as those of local ranchers in the Jefferson Valley. Low flows cause slower current speeds, and the water warms rapidly during the dog days of summer.
The Montana nights become noticeably shorter, and the year’s first cool front typically hits the region sometime in late August. This combination reinvigorates the trout in the river with oxygen-rich, cold water.
Tricos will be out in good numbers throughout August. Pods of rising trout can be found feeding on the spinners in back eddies and along foam lines during the morning hours. Anglers fishing the upper stretches between Whitehall and Twin Bridges will find more rising fish during Trico hatches.
Cranefly activity varies throughout the river, but noting their presence will tell the experienced angler to try skating large dries through skinny riffles during the morning hours.
Hoppers, ants, and beetles are around and serve as the primary insect food source for the trout of the Jefferson this time of the year. River stretches next to agricultural fields can come alive with active fish as ranchers cut and bail alfalfa and other crops. Grasshoppers seek refuge near the river’s edge, many of which invariably end up in the river on windy days.
Fishing large grasshopper imitations with a Clouser Cray dropped at around 5ft works well at attracting large trophy trout. Using a shorter leader around 7.5-9ft with a 3x tippet will help turn over these heavier setups. Between Silver Star, MT, and Cardwell, MT, there is prime late Summer water with undercut banks and foam eddies that hold good trout populations when irrigation and weather warms the river.
Dry/dropper rigs are the go-to Montana fly fishing setup for August. Fishing large hopper patterns with weighted nymphs on a long dropper is a great way to search for active fish below riffles and along mid-river foam lines.
Although dead-drifting a single hopper will move some trout out of the deep pools, fish in the Jefferson also respond well to large flies that are twitched or “skated” across the river while floating the Jefferson.
Nymphing below riffles and in deep pools that hold trout during the summer heat can be productive throughout the day. We tend to use a large Crayfish or Sculpin pattern with a searching nymph like a small lightning bug for summertime nymph fishing on the Jefferson. Twitching this setup in the slow, deep trout-filled pools will entice some of the larger Brown Trout to move for the flies throughout the morning hours.
The Yellowstone, Madison, and Gallatin are better day trip choices for most of our guests in August. Jefferson River fishing tends to be inconsistent during the best of times and this is even more the case with the low flows and warm water temperatures.
When conditions improve with cooling temperatures, the fish begin to feed more regularly, and our guides will suggest giving the Jefferson a try when we have experienced anglers fishing with us for a few days.
We have been guiding anglers fishing throughout Montana for over 23 years and understand the correlation between water conditions and fishing quality during the warm, summer months. A Jefferson River fishing trip is not for everybody, but if solitude and big fish opportunities are appealing to you, then let’s keep it as an option if the conditions are favorable.
Reservations for our guided Bozeman fly fishing day trips can be placed online, via e-mail, or by calling us at 1-406-468-5016. Contact our experts for help creating a custom Montana fly fishing trip that includes a day of Jefferson River fishing.