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.
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 21:00

12:00(now) — Western Blue-Winged Olive

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

Peak activity at 21:00 — 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
Fly box · Brown Trout
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
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