Freestone · Mixed · Colorado, US

Colorado River — Upper (Kremmling / Pumphouse / Gore Canyon)

A wide valley view of the Colorado River meandering below golden autumn hillsides near Kremmling, Colorado.

The upper Colorado around Kremmling — Pumphouse, the State Bridge water, the brink of Gore Canyon — is big, floatable trout water and a cornerstone of the state's identity, holding browns, rainbows and whitefish.

Tomorrow · About as good as it gets
Orange Stimulator
Forecast · Tomorrow
About as good as it gets
On the feed top to bottom — start on the rises with a dry, drop a nymph if they stay down.
75% projected
Today's fly
Orange Stimulator
Orange Stimulator
Conditions on the water · Tomorrow
Live gauge
Level
Steady
1.37 m
Water temp12.1°C
ClarityClear
Weather17°C
WindN 8 km/h
Pressure1018 hPa
Rain · recent0.0 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 Rainbow Trout
Ideal
12°C est.ideal 10–18°C
0°14°28°
How to fish it · for Rainbow 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
Water at 19.9°C — above the brown trout caution line (18°C). Fish dawn or dusk only. Land it fast, wet hands, no air shots.
Likely species
Mayflies
Caddisflies
Hatch timeline · tomorrowPeak at 12pm

12pm(now) — Mahogany Dun

Stage: On emergersApproach: Emerger or dryActivity: 95%
Also:Reed Smut47%Flying Ants33%
Peak emergence window8 food groups active

Peak activity at 12pm — Mahogany Dun (Mahogany Dun, Peak emergence window)

Sub-surface · on the nymphunder the surface

Hatch predictions

See the full sub-surface read with Pro.

Start free trial

14-day free trial. Cancel anytime.

Beyond the hatch · worth watchingambient prey(1)

Hatch predictions

See what else is on the menu with Pro.

Start free trial

14-day free trial. Cancel anytime.

Evidence
Records-basedModerate confidence

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

Through the year
0–3 scale · September 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
Brown DunHatch
2
3
3
3
3
3
3
2
Western Green DrakeHatch
2
2
Flav (Small Western Green Drake)Hatch
2
3
2
Mahogany DunHatch
2
2

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

Ranked for today
Rainbow Trout fly box
SD
Sex Dungeon
2-6 · Pattern
Proven pattern for this period
Permits & access
Permit required — see local rules.
  • Colorado licence
  • CPW Quality Water; verify reach rules and watch for voluntary low-flow/temperature closures.
What's coming
Plan ahead
5-day outlook
Cooler water nearby · 2
Water here at 19.9°C — the fishing's alive, but these are cooler if you'd rather rest the warm water.
Blue River (below Dillon)
55 km
~8°C
Rainbow trout · Brown trout
Eagle River (Vail to Gypsum)
52 km
~13°C
Brown trout · Rainbow trout
Gallery · 2
  1. A wide valley view of the Colorado River meandering below golden autumn hillsides near Kremmling, Colorado.
    The Colorado River - Grand County Colorado
  2. Terrain map of the venue
    Terrain map
About this water

The upper Colorado around Kremmling — Pumphouse, the State Bridge water, the brink of Gore Canyon — is big, floatable trout water and a cornerstone of the state's identity, holding browns, rainbows and whitefish. It's also the river most visibly squeezed by the way Colorado moves its water: diversions over the divide drop the flow, summer warms it, and recreation crowds the rest. After the June runoff it's wonderful float fishing with hoppers and attractors. In the low warm afternoons of high summer it's a river to leave alone, and a responsible app says so out loud.

  • Mixed
Conservation note

Mountain whitefish present. Sculpin/streamer ecology. Native cutthroat in upper tributaries (conservation-sensitive, prose only).

Water quality · US Clean Water Act
  • Aquatic life: Supporting
What this classification means

EPA ATTAINS assessment unit 'Colorado River, all tributaries' (COUCUC07a_D), 2024 Integrated Report. Aquatic Life use: Fully Supporting. 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) · COUCUC07a_D

The full read · show the working · for Rainbow Trout · confidence 80%
How the 28 is built — score × weight = contribution
Temperature32 × 28%9.0
Flow80 × 22%17.6
Clarity85 × 18%15.3
Feeding Time50 × 13%6.5
Pressure75 × 7%5.3
Insect activity51 × 12%6.1
Conditions total= 60
Can you trust it?
Water temperaturelive gauge readinggauge
Level / flowon-river gaugeobserved
Prey activitymodelled from regional profilemodelled
What would change the calculation
Cooler water — back toward the 10–18 °C ideal band — would lift the score and ease welfare.
The dawn and dusk windows score higher than the midday lull.
Directions
Apple MapsGoogle Maps
Seasons & zones
  • Trout 1 January → 31 December
Related guides
Euro Nymphingsubsurface methods
Booking & contacts