Mountain Freestone · Mixed · US, US

South Fork Trinity River

South Fork Trinity River

The South Fork of the Trinity is the wild one — the longest free-flowing river left in California, running undammed out of the Yolla Bolly country through deep forested canyon to meet the main Trinity.

Tomorrow · About as good as it gets
Pheasant Tail 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
Pheasant Tail Nymph
Pheasant Tail Nymph
Conditions on the water · Tomorrow
Live gauge
Level
Steady
0.79 m
Water temp13.2°C
ClarityClear
Weather17°C
WindN 5 km/h
Pressure1016 hPa
Rain · recent0.0 mm
Rain · ahead0.4 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
13°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
Hatch timeline · tomorrowPeak at 12pm

12pm(now) — Mahogany Dun

Stage: On emergersApproach: Emerger or dryActivity: 53%
Peak emergence window4 food groups active

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

Sub-surface · on the nymphunder the surface

Hatch predictions

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Beyond the hatch · worth watchingambient prey(1)

Hatch predictions

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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
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
What's coming
Plan ahead
5-day outlook
Other water nearby · 5
Gallery · 2
  1. South Fork Trinity River
  2. Terrain map of the venue
    Terrain map
About this water

The South Fork of the Trinity is the wild one — the longest free-flowing river left in California, running undammed out of the Yolla Bolly country through deep forested canyon to meet the main Trinity. That wildness is its character and its catch: with no dam to steady the flows, it runs high and cold with the winter rains and snowmelt, then drops and warms hard through the rainless summer. It's a steelhead and salmon river first, with resident rainbows holding in the cooler reaches, and the steelhead fishing follows the wet-season flows that draw fish up from the Trinity. Summer can leave the lower river low and warm enough that the fish need refuge, not anglers. Fish it when the water is up and cool, walk into the canyon for the wild trout, and respect a river that still runs the way rivers are supposed to.

  • River
  • Mixed
The full read · show the working · for Brown Trout · confidence 75%
How the 82 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 activity68 × 12%8.2
Conditions total= 82
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.
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