Blue River Fly Fishing Report: October Insights & Top Fly Patterns

The Blue River near Silverthorne is a catch-and-release fishery, and anglers are encouraged to use barbless hooks. Respect the private property boundaries along certain sections and use designated public access points. Always carry a valid Colorado fishing license and practice responsible fishing to protect this unique tailwater environment.

Updated: October 30, 2025

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The Blue below Dillon is glassy, cold, and technical—exactly what you’d expect this time of year. The trout are visible, picky, and painfully smart. Every cast is a job interview, and most get rejected. Still, those who play the stealth game right are finding pods of rainbows sipping midges and mysis-fed browns hugging the seams below the dam outflow.

Flows are stable but low, clarity is perfect, and fish are feeding light. Small midges and shrimp imitations dominate; streamers move the occasional bruiser early and late.

Conditions Summary

Flow: 95 CFS →
Water Temp: 36°F ↓
Air Temp (5-day): 24–47°F ↓
Clarity: Ultra Clear
Pressure: High
Best Times: 10:00 AM–2:30 PM
Dry Fly Score: ⭐⭐
Nymph Score: ⭐⭐⭐⭐
Streamer Score: ⭐⭐

The water is clear and cold with light midge activity. Sight fishing is productive mid-day when the sun hits the seams, but long leaders and quiet wading are essential.

Top Flies for Late October

Dry Flies

• Griffith’s Gnat #22–24; single on 7X; fish to slow-rising pods mid-day.
• Parachute Adams #22; dry-dropper with RS2 or black beauty; great for picky sippers.
• CDC Midge Adult #24; perfect in slick tailouts when noses start showing.

Nymphs

• Mysis Shrimp #18–20; near-dam must-have; fish deep under light indicator.
• Mercury Black Beauty #22–24; trail behind shrimp; deadly for rainbows.
• WD-40 Gray #22; dropper 10–12 inches off PT; subtle mid-column drift.

Streamers

• Mini Sculpzilla Olive #12; fish low light edges, short strips across current.
• Black Leech #10; swing near seams when flows pulse midday.
• Slumpbuster Natural #10; slow retrieve near deep pockets below town.
• How to Fish It: Two-fly nymph rig with 6X fluorocarbon. Drift through tailouts, not riffles. Drop shot lightly to keep flies ticking bottom without hanging up. When the midges lift, swap to a single dry or emerger.

October Hatch List 

• Midges (#22–26) | Size ★★★☆☆ | When: 10 AM–3 PM | How: double-midge nymph or emerger; lift slowly to trigger takes
• Blue-Winged Olive (#20–22) | Size ★★☆☆☆ | When: noon–2 PM on clouds | How: small sparkle dun or soft-hackle swing
• Mysis Drift (Dam Release) | Size ★★★★★ | When: all day below outlet | How: dead-drift shrimp pattern with trailing emerger

Tips for This Stretch

Stay low and move slow—these fish know the drill. Watch the outlet seam for mysis pulses; they come in waves. Focus on presentation, not pattern. If you’re getting refusals, shorten your dropper and lighten your indicator.

Access Points

Below the Dam Parking Lot; most consistent flows, but extreme pressure—work seams others ignore.
Blue River Trail Through Silverthorne; easy access behind the outlets and bridges, sight fish to visible rainbows.
Blue River Parkway Bridge; softer seams and shade; good midge action mid-day.

Local Regulations and Notes

Catch-and-release only. Flies and lures permitted. Avoid fishing directly below redds; some late spawners remain. Early mornings bring thin ice along the banks—move carefully.

FAQ on This Spot

Q: Are Mysis Shrimp still working?
A: Absolutely, but smaller sizes (#20) are key.

Q: When’s the best window?
A: 10:30 AM–2:00 PM on overcast days.

Q: Worth throwing streamers?
A: Only early or late—use small natural patterns.

Q: Indicator or Euro?
A: Yarn or tight-line; plastic bubbles spook fish here.

Q: Can I sight fish?
A: Yes—clarity is perfect. Approach slowly.

Q: What’s the best dropper combo?
A: Mysis Shrimp followed by Mercury Black Beauty.

Q: Are flows stable?
A: Yes—steady around 90–100 CFS this week.

Q: Parking tips?
A: Use the outlet mall lots early; it fills fast on weekends.