Tailwater · Mixed · Montana, US

Sun River

Sun River venue image

The Sun comes off the Rocky Mountain Front below Gibson Dam and runs down toward Great Falls, and it's a river ruled by the irrigation calendar.

Tomorrow · About as good as it gets
Czech Nymph
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.
90% projected
Today's fly
Czech Nymph
Czech Nymph
Conditions on the water · Tomorrow
Live gauge
Level
Steady
0.76 m
Water temp11.5°C
ClarityClear
Weather16°C
WindN 9 km/h
Pressure1007 hPa
Rain · recent0.0 mm
Rain · ahead0.6 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
12°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
Excellent — water temperature is working for you, but time of day is the limiting factor today.
Likely species
Mayflies
Caddisflies
terrestrials
Hatch timeline · tomorrowPeak at 11am

12pm(now) — Western Blue-Winged Olive

Stage: On emergersApproach: Emerger or dryActivity: 90%
Also:Black Midge54%
Peak emergence windowWeather boost8 food groups active

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

Sub-surface · on the nymphunder the surface

Hatch predictions

Top nymph shown — see all 4 guilds with Pro.

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Beyond the hatch · worth watchingambient prey(1)

Hatch predictions

Top prey shown — see all 4 with Pro.

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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
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
Brown Trout fly box
Permits & access
Permit required — see local rules.
  • Montana licence
  • Flow is irrigation-release controlled; the lower river draws down badly in summer.
What's coming
Plan ahead
5-day outlook
Other water nearby · 2
Dearborn River
47 km
82
Rainbow trout · Brown trout · Cutthroat trout
Missouri River
56 km
73
Rainbow trout · Brown trout
Gallery · 1
  1. Terrain map of the venue
    Terrain map
About this water

The Sun comes off the Rocky Mountain Front below Gibson Dam and runs down toward Great Falls, and it's a river ruled by the irrigation calendar. The upper reaches below the dam hold good browns and rainbows in cold, clear water; the lower river gets sucked down for the farms come summer and isn't worth your time when it's low and warm. What the dam lets out is the hand you play. Fish the upper water in the cool months and watch the release before you make the drive.

  • Mixed
The full read · show the working · for Brown Trout · confidence 75%
How the 81 is built — score × weight = contribution
Temperature100 × 28%28.0
Flow80 × 22%17.6
Clarity95 × 18%17.1
Feeding Time40 × 13%5.2
Pressure80 × 7%5.6
Insect activity64 × 12%7.7
Conditions total= 81
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