The Clark Fork is looking like one of the more promising rivers around Missoula as we approach another fall weather system. Recent flow measurements above Missoula have been around 1,500–1,530 cfs, a little higher than the readings from earlier in October. That additional water is a welcome change, offering trout more comfortable holding areas along deeper riffles, foam lines, banks, and current seams.

Water temperatures have cooled significantly compared with September, and the river is now fishing in a more traditional autumn pattern. Cold mornings may produce slower fishing, but the bite should improve from late morning into the afternoon as water temperatures rise slightly and insect activity increases.

The weekend's relatively dry conditions helped keep the river clear, but another change is approaching. Wednesday should remain pleasant, with mild temperatures and some afternoon sunshine. Thursday brings clouds and showers, followed by much colder, wetter conditions Friday. This could be an excellent setup for the Clark Fork's fall mayfly hatches.

Look for trout feeding along foam lines, slower riffle edges, inside bends, soft banks, tailouts, and deeper green lanes. The Clark Fork can be particularly technical when fish are feeding on the surface. Spend time observing before casting, and use a long leader with a careful presentation when targeting rising trout.

Fall Hatches

BWOs are becoming the most important mayflies to watch on the Clark Fork. The approaching cloudy weather should create favorable conditions for these small insects, particularly during the afternoon. Watch for rising fish in slow current seams and softer water adjacent to riffles.

Mahogany Duns can still produce worthwhile activity, and Hecubas remain an option as the fall hatch cycle winds down. Anglers are already seeing October Caddis, so keep larger adult imitations and pupa patterns ready.

The terrestrial program is fading, but there is still a chance to find fish on beetles, ants, and an occasional hopper during warmer afternoons. Concentrate these patterns around grassy banks and islands rather than treating them as an all-day searching option.

Nymphing is a dependable backup when fish aren't rising. Try Frenchies, Pheasant Tails, Perdigons, BWO nymphs, and October Caddis pupa through deeper seams. Fish the slower edges of current whenever water temperatures are particularly cold.

Streamer fishing is another excellent option as October progresses. Cooler water and cloudy skies can get larger brown trout moving. Fish Sparkle Minnows, Kreelexes, Peanut Envies, and smaller articulated streamers along banks, drop-offs, shelves, and deeper structure.

Outlook for the Weekend

Thursday and Friday's approaching weather system could produce excellent BWO and streamer conditions. If rainfall raises flows slightly without heavily muddying the river, fishing may improve. Saturday should bring colder temperatures and a more settled pattern.

What's Working

Dry Flies

• BWO Comparaduns #18–22

• BWO Emergers #18–22

• Mahogany Duns #14–16

• Hecubas #10–12

• October Caddis Adults #8–12

• Parachute Adams #16–20

• Purple Haze #16–20

• Griffith's Gnats #18–22

• Beetles #12–16

• Ants #14–18

Nymphs

• Pheasant Tails #16–20

• Frenchies #14–18

• Perdigons #16–20

• BWO Nymphs #18–22

• October Caddis Pupa #8–12

• Caddis Pupa #14–18

• Zebra Midges #18–22

• Prince Nymphs #12–16

• Worm Patterns

Streamers

• Sparkle Minnows

• Peanut Envy

• Kreelex

• Mini Dungeons

• Thin Mints

• Sculpzilla

• Woolly Buggers

• Small Sculpin Patterns