Montana ·
Missouri River Fly Fishing Report - August 8/23/2025
MISSOURI RIVER FLY FISHING REPORT
Montana's Classic Tailwater — Holter Dam to Cascade
Report Date: August 23, 2025 | Next Update: August 30, 2025
Current River Conditions
Late‑August rhythm: reliable tailwater flows with solid nymphing and surface opportunities in the cooler windows. Expect morning trico activity and consistent afternoon terrestrial action — a great time for mixed tactics.
Flows & Clarity
Typical tailwater releases below Holter Dam
Flow Rate: ~3,600–3,800 CFS (stable, check before you launch)
Water Clarity: Clear to lightly stained in back eddies — good visibility for both dries and indicator work.
Typical tailwater releases below Holter Dam
Flow Rate: ~3,600–3,800 CFS (stable, check before you launch)
Water Clarity: Clear to lightly stained in back eddies — good visibility for both dries and indicator work.
Water Temperature
Current: mid‑60s °F (around 62–65°F typical this time of year)
Trend: warm afternoons, cooler mornings — prime windows for surface feeding.
Current: mid‑60s °F (around 62–65°F typical this time of year)
Trend: warm afternoons, cooler mornings — prime windows for surface feeding.
Weather & Wind
Pattern: warm afternoons, mornings cool; breezy in open stretches.
Strategy: fish low, calm-water pockets early; use banks and eddies for protection from wind.
Pattern: warm afternoons, mornings cool; breezy in open stretches.
Strategy: fish low, calm-water pockets early; use banks and eddies for protection from wind.
Access & Logistics
Main access: Holter Dam downstream through Cascade area — boat ramps open.
Crowds: moderate on weekends; weekdays and early morning/late evening offer quieter water.
Main access: Holter Dam downstream through Cascade area — boat ramps open.
Crowds: moderate on weekends; weekdays and early morning/late evening offer quieter water.
Hatch Chart & Insect Activity
| Insect | Size | Activity Level | Prime Time |
|---|---|---|---|
| Tricos (spinner fall) | #18–22 | High (notable morning surface sipping) | First light to mid‑morning — tight drifts in seams and along foam lines |
| PMDs & Small Mayflies | #14–18 | Moderate | Late morning when water is calm |
| Caddis | #14–18 | Light to moderate | Evening edges and near structure |
| Terrestrials (hoppers, ants) | Size 6–12 (hopper silhouettes) | High in afternoons | Warm afternoons on flats and bank margins |
| Midges & Midges Pupa | #18–22 | Consistent (subsurface) | All day — great for euro/nymph rigs in slack water |
Recommended Flies (matched to available patterns)
Below are practical fly selections for right now. Each pattern links to a ready tie/purchase from the fly sheet so you can stock up quickly.
| Purpose | Pattern (click to view) | Suggested Sizes |
|---|---|---|
| Trico & Tiny Dry | Top Secret Baetis / Stealth Link BWO | #18–22 |
| PMD Dry & Emerger | Stealth Link Mercer - PMD / Tungsten Split Case Nymph - PMD | #14–18 (dry), #14–16 (nymph) |
| Small Midges / Indicator Nymphing | Black Zebra Midge (TBH) | #18–22 |
| Stonefly / Big Nymph (for pockets & riffles) | Jiggy Pat's (Stonefly/Pat's Rubber Legs style) / Tungsten Pat's Rubber Legs | #6–10 |
| Hoppers & Terrestrials | Fancy Pants Hopper - Tan / Bionic Hopper - Tan | #8–12 |
| Streamers / Sculpin Imitations | Coffey's Articulated Sparkle Minnow - Sculpin #4 / Sculpzilla - Natural | #4–6 (streamer sizes) |
| Eggs & Attractors for late summer | Sunny Side Up - Apricot | #12–16 (egg sizes) |
| Soft Hackle / Subsurface | Soft Hackle Pheasant Tail Jig - Barbless / Pheasant Tail Tungsten | #14–18 (jig/soft hackle), #12–16 (pheasant tail) |
| Salmonfly / Big Dry (where present) | Libby's Salmonfly | #4–8 |
Tactics & Quick Tips
Morning: fish the seams and grass flats with short indicator rigs or euro nymphs — trico spinner activity can produce picky surface takes; use tiny parachute or emerger imitations and long, drag‑free drifts.
Midday: PMD and midge activity favors tight, accurate casts to foam lines and inside seams. If the surface is quiet, go subsurface with tungsten nymphs and small midges.
Afternoon: hoppers and terrestrials come into play — switch to hopper/dropper or a dry hopper with a heavy nymph beneath for fish holding in skinny water.
Streamer Game: target structure, tailouts and deeper seams with sculpin/baitfish streamers on an intermediate line or sink-tip; short strips with pauses trigger reaction strikes from bigger browns.
Crowd & Safety Note: on weekends expect more boats and drift-anglers. Launch early, wear a life jacket in a boat, and be courteous when working popular stretches.
Midday: PMD and midge activity favors tight, accurate casts to foam lines and inside seams. If the surface is quiet, go subsurface with tungsten nymphs and small midges.
Afternoon: hoppers and terrestrials come into play — switch to hopper/dropper or a dry hopper with a heavy nymph beneath for fish holding in skinny water.
Streamer Game: target structure, tailouts and deeper seams with sculpin/baitfish streamers on an intermediate line or sink-tip; short strips with pauses trigger reaction strikes from bigger browns.
Crowd & Safety Note: on weekends expect more boats and drift-anglers. Launch early, wear a life jacket in a boat, and be courteous when working popular stretches.
Where to Focus
- Grass flats and shallow riffles below Holter Dam for numbers and aggressive rainbows.
- Bank seams and foam lines during spinner falls — long drifts win more often than flashy presentations.
- Deeper runs and structure for streamer work; target edges of current and undercut banks.
- Slack water pockets and near bank back eddies for euro nymphing and midge pupa patterns.
Regulations & Conservation
Follow current Montana FWP rules for the Missouri River stretch you are fishing. Practice barbless hooks where required or preferred, handle fish quickly, and wet hands before release. Check for seasonal closures or special regulations near dams and spawning tributaries before you go.
