Tailwater · Mixed · Colorado, US

Big Thompson River (canyon, below Lake Estes)

The Big Thompson River flowing over cobblestones through pines and aspens, Colorado.
Today · Not the day for it
Pheasant Tail
Forecast · Today
Not the day for it
Not much stacked in your favour today. Worth an hour if you are nearby, not worth the special trip.
45% projected
Today's fly
Pheasant Tail
Pheasant Tail
Conditions on the water · Today
Live gauge
Level
Rising
0.28 m
Lifting fast
Water temp10.0°C
ClarityUnfishable
Weather8°C
WindN 14 km/h
Pressure1025 hPa
Rain · recent3.7 mm
Rain · ahead0.0 mm

The nearest gauge doesn't record temperatures, so we've estimated it — defer to the river keeper's advice.

Water temperature for Brown Trout
Ideal
10°C est.ideal 10–16°C
0°14°28°

A dam sets this river's temperature, not the weather, so it can shift several degrees within hours when the release changes. It also warms as it runs away from the dam.

How to fish it · for Brown Trout
When
Nymphing can work through most of the day.
Where
Cover mixed depths.
Method
Start with tight-line nymphs and adjust if fish rise or drift higher.
Kit
9 ft #4 rod, floating line, 12 ft tapered leader to 4–5 lb fluoro tippet.
Why this works
Excellent — conditions well-balanced, with water temperature particularly in your favour.
Likely species
Mayflies
Chironomids
Damselflies & dragonflies
Gammarids
Hatch timeline · todayPeak at 11 Uhr

12 Uhr(now) — Western Blue-Winged Olive

Stage: On emergersApproach: Emerger or dryActivity: 56%
Also:Black Midge30%
Peak emergence window4 food groups active

Peak activity at 11 Uhr — Western Blue-Winged Olive (Western Blue-Winged Olive, Peak emergence window)

Sub-surface · on the nymphunder the surface

Hatch predictions

Supporters see the full sub-surface read.

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Beyond the hatch · worth watchingambient prey(1)

Hatch predictions

Top prey shown — see all 3 as a supporter.

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Evidence
Records-basedModerate confidence

Based on species-occurrence records, not local invertebrate surveys.

Through the year
0–3 scale · October highlighted
J
F
M
A
M
J
J
A
S
O
N
D
Trout seasonSeason
1
2
2
2
2
2
2
2
2
2
2
1
Western Blue-Winged OliveHatch
2
3
3
3
3
3
3
3
2
Pale Morning DunHatch
2
3
3
2
TricoHatch
2
3
2
Black MidgeHatch
2
3
3
3
3
3
3
3
3
3
3
2

Numbers are intensity 0 (none) to 3 (peak) — a guide, not a guarantee.

Ranked for today
Fly box · Brown Trout
Permits & access
Permit required — see local rules.
  • Colorado licence
  • Wild Trout catch-and-release flies/lures section in the canyon — verify CPW rules
  • Roadside access throughout the canyon.
What's coming
Plan ahead
5-day outlook
Other water nearby · 3
St. Vrain Creek (Lyons)
22 km
78
Brown trout · Rainbow trout
Cache la Poudre River
28 km
75
Brown trout · Rainbow trout
Boulder Creek (Boulder Canyon)
46 km
75
Brown trout · Rainbow trout
Gallery · 3
  1. The Big Thompson River flowing over cobblestones through pines and aspens, Colorado.
    Listening While the River Runs - Big Thompson River
  2. Venue photo
  3. Terrain map of the venue
    Terrain map
Water quality · US Clean Water Act
  • Aquatic life: Impaired
What this classification means

EPA ATTAINS assessment unit 'Big Thompson River, mainstem' (COSPBT02_F), 2024 Integrated Report. Aquatic Life use: Not Supporting. Listed impairment causes: Metals Other Than Mercury. This is a Clean Water Act assessment-unit classification (the US analogue of WFD), not a live reading.

Status is for the Clean Water Act assessment unit covering this reach.

EPA ATTAINS (Clean Water Act) · COSPBT02_F

The full read · show the working · for Brown Trout · confidence 90%
How the 85 is built — score × weight = contribution
Temperature100 × 28%28.0
Flow80 × 22%17.6
Clarity95 × 18%17.1
Feeding Time70 × 13%9.1
Pressure80 × 7%5.6
Insect activity67 × 12%8.0
Conditions total= 85
Can you trust it?
Water temperatureair-to-water estimateestimated
Level / flowon-river gaugeobserved
Prey activitymodelled from regional profilemodelled
Directions
Apple MapsGoogle Maps
Seasons & zones
  • Trout 1 January → 31 December
Related guides
Euro Nymphingsubsurface methods
Booking & contacts