Cold Montana rivers set up a patient streamer-and-nymph week

What's next

With water already in the mid-40s, expect trout to hold in slower seams and deeper runs rather than ripping through riffles. The warmest part of the afternoon is the best window, when water edges up by a degree or two and fish become more willing to move. Early mornings will be slower.

MT FWP Fishing News reminds anglers that spawning closures on some rivers begin Oct. 1, and it also reported lifting an angling closure on Section 5 of the Big Hole River after rain improved flows. The Section 1 closure was to remain in place. Check current Fishing Access Site and river-section rules before you go, as closures can change quickly.

Trout Unlimited's recent TROUT Tip stresses that weight on a nymph rig matters. With flows in the 1,200 to 1,300 cfs range at gauges 06041500 and 06041000, add enough weight to reach the bottom in the heavier runs and lighten up in the softer water.

First quarter moon gives decent evening light early in the night, though it matters little for trout. Plan around temperature and light instead.

Context

Mid-October on southwest Montana rivers is typically the tail end of the fall streamer window, with brown trout moving toward spawning and feeding aggressively ahead of it. Small dries and midges still tend to show on overcast afternoons, which fits Flylab's note that it is the time of year for small dries. Flows at these levels and temperatures are on schedule for the season, and winter low-flow conditions are not far off. Anglers should typically avoid wading over spawning redds, and check state regulations before fishing any section.