Blue River Fly Fishing Report at Dillon Dam –12/4/25

One of Colorado’s most technical winter tailwaters, running cold and clear right now.

Updated: 12/4/2025

Flows below Dillon Dam remain low and steady, with nearly no week-over-week change. The water is exceptionally clear, forcing trout into deeper, slower lanes and making presentation everything. Feeding windows are narrow but predictable, driven mostly by mid-day midge activity. Crowds have thinned out with colder weather, but the fish remain selective and spooky. Anglers who adjust depth, downsize tippet, and present micro patterns naturally are seeing the best results.

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Conditions Summary

Flow: Low and stable; no meaningful change this week
Water Temperature: High 30s to low 40s; trending slightly downward
Air Temperature: 20s early, upper 30s mid-day
Clarity: Extremely clear; trout are spooky and selective
Crowds: Low to moderate; winter thins out foot traffic in town
Best Window: 11 am to 3 pm when sunlight hits the canyon and midges pop
Fishing Type Focus: Nymphing with micro patterns, because ultra-clear water forces trout into slow lanes where small midges drift naturally

Weather

Expect frosty mornings, brief mid-day warmth, and canyon shade that keeps water temps low. Cloud cover improves midge emergence and reduces fish spookiness.

Top Flies in Your Box This Week

• Mercury Midge 20–22
• Black Beauty 20–24
• Top Secret Midge 22–24
• RS2 Gray 20–22
• Chocolate Thunder 20–22
• JuJu Midge Purple 20–22
• WD40 Brown 20–22
• Rainbow Warrior 20–22
• Bling Midge 20–22
• Mini Leech Black 14

Pro Rig of the Week – The Silverthorne Micro Tailwater Rig

Leader: 9–10 ft tapered to 6x fluorocarbon
Top Fly: RS2 Gray 22
Dropper: Top Secret Midge 24
Indicator: Small yarn or tiny AirLock set extremely light
Weight: Micro split-shot only, adjusted for depth constantly
Target Water: Slow seams, deep troughs, and edges of structure where trout stack tightly in winter clarity

Hatch Chart for December

Access Points

Blue River Trail Access (Town Section)
Easy access, clear water, spooky trout, highly technical fishing.
Rating: ⭐⭐⭐

Below the Dillon Dam Outlet
Coldest section but consistent midge drift; the most predictable winter holding water.
Rating: ⭐⭐⭐⭐

Silverthorne Factory Outlet Area
Narrow lanes, deep slots, and sight-fishing opportunities in clear water.
Rating: ⭐⭐⭐

Bike Path Pull-Offs (South)
Soft water and deeper holding zones less pressured in winter.
Rating: ⭐⭐⭐⭐

North Pond Area Transition Water
Wider runs with moderate depth; less foot traffic.
Rating: ⭐⭐⭐

Stop Here After the River

Angry James Brewing Co. (Silverthorne)
A relaxed post-river hangout with warm food-truck meals, mountain-town energy, and reliably good beer.
What to order: The Resolute IPA with a rotating hot entrée from the food truck lineup.

Local Regulations & Notes

• Tailwater flows can shift with dam operations
• Expect icy banks in shaded areas
• Barbless hooks encouraged for winter handling
• Trout are exceptionally selective in clear water; natural drifts matter

FAQ

Q: Is this stretch tougher in winter?
A: Yes, due to low flows and extreme clarity.

Q: Do I need 6x tippet?
A: Almost always in this section.

Q: Can I sight-fish here?
A: Yes, especially during low sun with polarized light.

Q: Are streamers productive?
A: Only small leeches fished slow.

Q: When does the best midge hatch occur?
A: Mid-day during cloud cover.

Q: Do flows change much week to week?
A: Rarely; winter releases remain stable.

Companion Article

Colorado Winter Trout Feeding Behavior in Clear Tailwaters