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The tailwater is running cold, clear, and brutally honest, with trout holding deep in slow winter seams and floodwall lanes. Feeding windows are short but consistent when sunlight reaches the water, and every drift gets evaluated like a résumé. This is classic Blue River winter fly fishing: technical, precise, and deeply rewarding if you do everything right.
Updated: December 15, 2025
The Blue River below Dillon Dam is fully locked into its winter tailwater pattern. Bottom-release flows keep water temperatures stable, clarity exceptional, and trout behavior consistent day to day. Fish are holding tight to deeper troughs, inside seams, and floodwall edges where current softens just enough to allow efficient feeding.
This week’s update for Blue River Dillon Dam fly fishing centers on discipline. Midges dominate the menu, baetis nymphs appear briefly during mild afternoons, and weight control matters more here than almost anywhere else in Colorado. If your flies are not occasionally ticking the bottom, you are not in the game.
Listen to the Audio Overview
Conditions Summary
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Flow: Stable winter tailwater release
Water Temperature: Low to mid 30s and consistent
Air Temperature: High 20s to mid 30s during the day, colder mornings
Clarity: Ultra clear
Crowds: Moderate due to accessibility
Best Window: 11 a.m. to 3 p.m.
Fishing Type Focus: Technical tailwater nymphing with tiny midges and perfect drifts
Weather
Cold mornings dominate the valley, with brief midday warming on sunny days. Calm conditions offer the best fishing. Wind through the corridor can shut things down quickly by making already technical drifts even harder to control.
Top Flies in Your Box This Week
- Black Beauty 20 to 24
- Zebra Midge (black or red) 20 to 22
- Mercury Midge 20 to 22
- Top Secret Midge 22 to 24
- RS2 (black or gray) 20 to 22
- WD-40 20 to 22
- Small Pheasant Tail 18 to 20
- Juju Baetis 20 to 22
Pro Rig of the Week: Dillon Dam Tiny Water Column Rig
- Indicator: Very small yarn or low-profile air-lock
- Lead Fly: Small Pheasant Tail 18 to 20 or RS2 20
- Dropper: Black Beauty or Top Secret Midge 22 to 24
- Weight: One micro to small split shot adjusted carefully
- Target Water: Floodwall seams, deep winter troughs, and slow inside edges
Hatch Chart for December
| Bug Type | Size | Notes |
|---|---|---|
| Midges | 20 to 26 | Dominant winter food source; trout feed almost entirely subsurface |
| Baetis nymphs | 20 to 22 | Active on warmer cloudy afternoons |
| Scuds | 16 to 18 | Less common than other tailwaters but still relevant |
| Winter stoneflies | 18 | Rare bonus movement |
Download the Blue River Hatch Chart
Access Points
Silverthorne Town Stretch ⭐⭐⭐⭐⭐
Classic floodwall water with consistent winter trout holding lanes.
Rating: Five gold stars
Blue River Trail Pullouts ⭐⭐⭐⭐☆
Long glides and deep seams with slightly less pressure.
Rating: Four gold stars
Lower Corridor Access ⭐⭐⭐⭐☆
Broader winter lanes and productive seams when flows are steady.
Rating: Four gold stars
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 and Notes
- Tailwater flows change; always check the release before fishing
- Extremely clear water requires long leaders and 6X tippet
- Sight-fishing is possible but demands quiet wading
- Respect town pathways and private property along the corridor
FAQ
Q: Is the Blue River below Dillon Dam good in winter?
A: Yes. Cold but consistent flows make it one of Colorado’s most predictable winter tailwaters.
Q: What weight rod should I bring?
A: A 4 or 5 weight with a long leader setup is ideal for this technical water.
Q: Are dries an option?
A: Rarely, but on the warmest calm afternoons you might find isolated midge clusters.
Q: What is the biggest mistake anglers make here?
A: Heavy footsteps and heavy rigs. Everything here requires subtlety.
Q: Does the flow matter more on a tailwater?
A: Yes. Even small changes from the dam can shift where trout stack.
Q: When is the best time of day?
A: Midday, when water temps rise the most.
Q: Is the Blue River good in winter?
A: Yes. It is one of the most consistent winter tailwaters in Colorado, but it is very technical.
Q: What is the biggest mistake anglers make here?
A: Fishing too heavy or too fast. Subtle depth control matters more than fly changes.
Q: Are dry flies an option right now?
A: Rarely. Subsurface midge patterns dominate winter success.
Q: What leader and tippet setup works best?
A: Long leaders with 5X to the lead fly and 6X to the midge dropper.
Q: Does wind ruin the fishing?
A: It can. Wind makes precise drifts extremely difficult on this stretch.
Q: When does the bite shut down?
A: Typically mid-afternoon once shadows and colder air settle into the corridor.
Companion Article