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The tailwater is running low and stable, clarity is exceptional, and trout are holding deep in slow technical slots. Expect short but meaningful midday feeding windows, especially when sunlight finally hits the canyon edges. This is pure Blue River winter tailwater fishing: precise, rewarding, challenging.
Updated: December 10, 2025
The Blue River below Dillon Dam is holding steady in its classic winter tailwater pattern. Cold ultra-clear water, steady bottom-release flows, and trout that behave like they’re interviewing you for a job. If you bring small bugs, quiet feet, and realistic expectations, this stretch will reward you. If you bring loud presentations or heavy steps, it will not.
This week’s update centers on the Blue River Dillon Dam tailwater, one of Colorado’s most technical winter fisheries. Fish are feeding, but they’re feeding with manners: small midges, tiny baetis, slow drifts, and subtle takes. Approach with care, think small, and remember that perfect drifts matter more here than anywhere else in Summit County.
Listen to the Audio Overview
Conditions Summary
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Flow: ~100 CFS below Dillon Dam, a stable winter release
Water Temperature: Low 40s near the dam outlet; colder downstream
Air Temperature: High 20s to mid 30s; nights in the teens
Clarity: Ultra clear
Crowds: Moderate around town access; light upstream
Best Window: 11 a.m. to 3 p.m.
Fishing Type Focus: Tailwater nymphing with small midges and baetis
Weather
Silverthorne Colorado Weather
Expect a cold dry pattern this week with sunny mornings, light afternoon breezes, and quick cooling once shadows lengthen along the bike path. Highs reach the upper 20s to mid 30s with lows in the teens. Midday provides the narrow but reliable window when trout feed most actively.
Top Flies in Your Box This Week
- Black Beauty 20 to 24
- Top Secret Midge 22 to 24
- Mercury Midge 20 to 22
- Zebra Midge (black or red) 20 to 22
- RS2 (black or gray) 20 to 22
- Juju Baetis 20 to 22
- Small Pheasant Tail 18 to 20
- Mole Fly 20 to 22
- Mini Leech (black) 12 to 14
Pro Rig of the Week: Dillon Dam Tiny Water Column Rig
- Indicator: Small yarn or white air-lock
- Lead Fly: Small Pheasant Tail 18 to 20
- Dropper: Black Beauty or Top Secret Midge 22 to 24
- Weight: Micro split shot, adjusted so it barely ticks bottom
- Target Water: Slower seams, deep slots along the floodwall, and gentle inside bends
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
Dillon Dam Outlet ★★★★★
Ultra-consistent tailwater structure with deep seams and high oxygenation. Best chance at selective but high-quality trout.
Rating: Five gold stars
Silverthorne Town Stretch ★★★★☆
Clear, technical, heavily pressured water with accessible paths and visible trout. Ideal for anglers who enjoy a challenge with sight-nymphing opportunities.
Rating: Four gold stars
Blue River Trail Upstream Access ★★★★☆
Quieter pocket water and soft seams away from the crowds. Great winter refuge water when town is busy.
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.
Companion Article
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