Freestone · Mixed · Colorado, US

Boulder Creek (Boulder Canyon)

Boulder Creek flowing swiftly through a rocky canyon lined with pine trees and granite boulders in Boulder Canyon, Colorado.

Boulder Creek up in Boulder Canyon is the quintessential Front Range small-water quick-hit — a tumbling little freestone right beside CO-119 that holds eager browns and rainbows and asks nothing more than a short cast and a willingness to scramble.

Today · About as good as it gets
Sculpin Streamer
Forecast · Today
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.
90% projected
Today's fly
Sculpin Streamer
Sculpin Streamer
Conditions on the water · Today
Live gauge
Level
Falling
1.39 m
Dropping after lift
Water temp9.6°C
ClarityClearing
Weather10°C
WindN 15 km/h
Pressure1025 hPa
Rain · recent1.9 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
Cool — slow
10°C est.ideal 10–16°C
0°14°28°
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
Good — water clarity is right today, though time of day could be better.
Likely species
Chironomids
Gammarids
Hatch timeline · todayPeak at 9pm

12pm(now) — Western Blue-Winged Olive

Stage: On emergersApproach: Emerger or dryActivity: 55%
Also:Black Midge37%
Peak emergence window5 food groups active

Peak activity at 9pm — Brown Dun (Brown Dun, 4 food groups active)

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 2 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
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
Brown Trout fly box
SD
Sex Dungeon
2-6 · Pattern
Proven pattern for this period
Permits & access
Permit required — see local rules.
  • Colorado licence
  • Wild Trout special-regulation section in Boulder Canyon — verify CPW rules.
What's coming
Plan ahead
5-day outlook
Other water nearby · 3
St. Vrain Creek (Lyons)
25 km
78
Brown trout · Rainbow trout
Clear Creek (Golden)
29 km
76
Brown trout · Rainbow trout
Big Thompson River (canyon, below Lake Estes)
46 km
85
Brown trout · Rainbow trout
Gallery · 2
  1. Boulder Creek flowing swiftly through a rocky canyon lined with pine trees and granite boulders in Boulder Canyon, Colorado.
    Boulder Creek, Boulder Canyon
  2. Terrain map of the venue
    Terrain map
About this water

Boulder Creek up in Boulder Canyon is the quintessential Front Range small-water quick-hit — a tumbling little freestone right beside CO-119 that holds eager browns and rainbows and asks nothing more than a short cast and a willingness to scramble. It's small enough to wade in tennis shoes and flashy enough to muddy up after a storm, with a Wild Trout section in the canyon for those who want to keep it honest. Nobody's driving across the state for it, but for an after-work hour out of Boulder it's hard to beat, and the upper canyon thins the crowd nicely.

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

EPA ATTAINS assessment unit 'Boulder Creek, mainstem and tributaries.' (COSPBO02b_G), 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) · COSPBO02b_G

The full read · show the working · for Brown Trout · confidence 90%
How the 75 is built — score × weight = contribution
Temperature72 × 28%20.2
Flow80 × 22%17.6
Clarity95 × 18%17.1
Feeding Time55 × 13%7.2
Pressure80 × 7%5.6
Insect activity62 × 12%7.4
Conditions total= 75
Can you trust it?
Water temperatureair-to-water estimateestimated
Level / flowon-river gaugeobserved
Prey activitymodelled from regional profilemodelled
What would change the calculation
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