Big Thompson Fly Fishing Report – Winter Low Flows, Clear Water, and Midday Action Below Lake Estes

Updated: December 5, 2025 – Morning check

The Big Thompson below Lake Estes is in full winter tailwater mode at 24.3 cfs, running cold and clear with typical early December baseflows. Expect technical nymphing in softer seams and pockets, with trout tucked deep and not moving far for food. You’re fishing a low, skinny river where stealth, light tippet, and tiny bugs matter way more than fly box variety.

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Conditions Summary

• Flow: 24.3 cfs, low and stable, classic winter tailwater flows; expect spooky fish and consolidated holding water in deeper slots and slow inside bends.
• Water Temperature: No live temp data, but assume mid-30s to low-40s in the prime window; fish will feed, but only in short bursts when light and temps line up.
• Air Temperature: 25.2°F at report time; it will feel colder in the canyon with shade and wind, so dress for full winter conditions.
• Clarity: Clear; great for sighting fish but unforgiving on sloppy wading, casting shadows, or heavy tippet.
• Crowds: Medium for winter; close to Estes and an easy day trip, so you’ll see some anglers but plenty of open water between popular pullouts.
• Best Window: Late morning through mid-afternoon, once the sun hits the canyon and air temps come up a bit; first and last light are more about survival than productivity right now.
• Fishing Type Focus: Nymphing tight to structure and depth transitions with small midges and winter stones, plus the occasional micro-dry or dry-dropper for risers in soft edge water during the warmest hour.

Weather

Cold, winter pattern with highs just above freezing and overnight lows in the teens. Expect mixed clouds and occasional snow showers, icy pullouts, and frozen guides until late morning. This is a layers, hand-warmers, and thermos kind of day.

Top Flies in Your Box This Week

You don’t need twenty patterns; you need the right half-dozen in the right sizes.

1. Parachute Midge – #20–22
2. Griffith’s Gnat – #20–22
3. Zebra Midge (Black/Silver) – #20–22
4. WD-40 (Brown/Gray) – #20–22
5. Top Secret Midge – #20–22
6. JuJu Midge – #20–22
7. Two Bit Hooker (Black or Red) – #18–20
8. RS2 (Gray/Olive) – #20–22
9. Mini Leech (Black or Olive) – #10–12
10. Egg Pattern (Cream/Peach) – #14–16

Pro Rig of the Week – “Skinny Canyon Winter Nymph Rig”

• Top Fly (Attractor / Upper Nymph):
  Two Bit Hooker #18 or small Stonefly nymph #16 on 4X–5X.
• Dropper (Primary Food / Midge):
  WD-40, JuJu Midge, or Top Secret Midge #20–22 on 5X–6X, 14–18 inches below.
• Indicator:
  Small yarn or air-lock style, sized to just float your split shot; keep it compact and subtle.
• Weight:
  1–2 small split shot; just enough to tick bottom in the deeper buckets without hanging up every cast.
• Target Water:
  Slow inside bends, softer seams below structure, and deeper winter pools where the current rolls over a shelf and softens. Think “walking speed or slower” and at least knee-deep.

Big Thompson Hatch for December

Early winter on the Big Thompson is all about midges and a few winter stones. Here’s how to stack your box for the month:

Download the Big Thompson Hatch Chart

Access Points

All below Lake Estes along US-34. Check road conditions and any temporary closures before you go.

Tailwater Below Lake Estes (Olympus Dam) – Directly below the dam in Estes Park. Short walks, easy access, and classic technical tailwater pocket water.
Rating: ⭐⭐⭐⭐☆

Aspen Glen / Canyon Pullouts – Series of pullouts as you drop into the canyon. Short scrambles to the river, mix of pocket water and short runs; great on low-flow winter days.
Rating: ⭐⭐⭐⭐☆

Sleepy Hollow to Viestenz-Smith Reach – Rebuilt public stretches with improved access, deeper pools, and nice holding water at lower winter flows.
Rating: ⭐⭐⭐⭐☆

Drake Area Pullouts – Around the town of Drake where the North Fork meets the main stem. More gradient and pocket water, but good slots if you work for them.
Rating: ⭐⭐⭐☆☆

Lower Canyon Pullouts (toward Loveland) – Numerous roadside pull-ins with longer glides and runs; great for covering water but more exposed to wind on colder days.
Rating: ⭐⭐⭐☆☆

Stop Here After the River

Finish the day at Rock Cut Brewing Company in Estes Park. It’s a locals’ spot with big windows and mountain views. Order the Trail Ridge IPA and a soft pretzel — the perfect end to a cold-clear canyon session.

Local Regulations and Notes

• Special Regulations: Check the CPW Big Thompson regulations for seasonal closures and specific tackle restrictions in certain canyon stretches.
• Private Property: Much of the river runs along private land; respect posted signs, fences, and driveways, and only use obvious public pullouts and trails.
• Winter Safety: Expect ice shelves, icy rocks, and slick banks. A wading staff and studs are smart, even at low flows.
• Road Conditions: US-34 can be icy and shaded in the canyon; watch for black ice in the morning and evening.

Big Thompson River FAQ

Is the Big Thompson below Lake Estes worth fishing in winter?
Yes, if you lean into the tailwater game: low flows, tiny bugs, and short mid-day bite windows. It’s a solid technical option when freestones are locked up.

What gear should I bring for December?
A 4–5 weight rod, 5X–6X fluoro, split shot, tiny indicators, and a box of midges, stones, and a few eggs. Waders with good insulation and traction are mandatory.

When is the best time of day to fish right now?
Late morning to mid-afternoon, when temps bump a few degrees and fish slide out of the absolute deepest water to feed.

Can I fish dry flies on the Big Thompson in this cold?
Occasionally. Watch soft edges and foam lines from noon to 2 PM for midge clusters and the odd riser. A Griffith’s Gnat or Parachute Midge will pick off the few heads you see.

How crowded should I expect it to be?
Moderate. It’s close to town and still fishable in winter, but the cold and snow thin things out. You’ll usually find open water by leapfrogging a couple of pullouts.

Is this a good option for beginners right now?
It’s fishable, but technical. New anglers will do better with a guide or more forgiving water in spring. Winter here rewards patience, good drifts, and precise rigging.

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Companion Article

Colorado Winter Trout Fishing Strategy and Behavior Guide

If you’re planning to work the Big Thompson (or any Colorado tailwater) through winter, read this next. It breaks down how trout behave in cold water, how to time your outings around temps and flows, and how to build winter rigs that keep you in the strike zone instead of just surviving the cold.