Freestone · Granite · Southern California, US

West Fork San Gabriel River (catch-and-release reach)

The West Fork of the San Gabriel is the trout stream on Los Angeles' doorstep, forty minutes from downtown up Highway 39 and then a walk or bike ride along the closed, paved West Fork Road.

Prime · Rainbow Trout
Parachute Adams · 16–20
Primelive now
About as good as it gets
Low and clear — careful approach country. Take your time — read the water before you cast.
90% confidence
What moved it
  • LevelDry recentlyNo gauge reading
  • Water temp12.8°C
  • ClarityClear
Today's fly
Parachute Adams
Parachute Adams16–20
Proven pattern for this period
Conditions on the water
Estimate
Level
Dry recently
No gauge reading
Water temp12.8°C
ClarityClear
Weather19°C
WindS 9 km/h
Pressure1014 hPa
Rain · recent0.0 mm
Rain · ahead1.8 mm

No gauge on this water — readings are regional estimates from weather, not a live gauge.

Water temperature for Rainbow Trout
Ideal
13°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
Excellent — water temperature is right today, though time of day could be better.
Likely species
Mayflies
Caddisflies
Blackflies
  • Blackfly larvae/pupaeMost likelyLower confidence
    #16–18–20 · Pupa
    Small dark soft-hackle drifted through riffle seams.
Chironomids
Aquatic beetles
Oligochaetes
  • Aquatic wormsMost likelyLower confidence
    #12–14–16 · Adult
    Dead-drift a worm pattern deep - a year-round staple.
Hatch timeline · todayPeak at 9pm

Hatch predictions

Today's headline hatch shown — see all 6 active hatches hour by hour as a supporter.

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Sub-surface · on the nymphunder the surface

Hatch predictions

Top nymph shown — see all 4 guilds as a supporter.

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Beyond the hatch · worth watchingambient prey(1)

Hatch predictions

Supporters see what else is on the menu.

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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
Sculpin (North America)Hatch
2
3
2
Brown DunHatch
2
3
3
3
3
3
3
2
SalmonflyHatch
2
3
2
Golden StoneHatch
2
3
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.
  • All year, barbless artificial lures, 0 trout, Cogswell Dam to the second bridge above Highway 39
  • California licence.
What's coming
Plan ahead
5-day outlook
About this water

The West Fork of the San Gabriel is the trout stream on Los Angeles' doorstep, forty minutes from downtown up Highway 39 and then a walk or bike ride along the closed, paved West Fork Road. From Cogswell Dam down to the second bridge above the highway it's barbless artificials only and catch-and-release all year, a granite-bottomed canyon creek of riffles and small pools. It is not a cold tailwater: the county dam releases in pulses, and late summer runs low and warm. The 2020 Bobcat Fire burned this canyon, and storms still bring sediment down, so a clear week after rain is the time to go.

  • Granite
Conservation note

Rainbow trout; whether they are wild or hatchery-derived is not established by CDFW. The West Fork is not on CDFW's designated Wild or Heritage Trout list — its catch-and-release status comes from the special regulations only.

The full read · show the working · for Rainbow Trout · confidence 90%
How the 82 is built — score × weight = contribution
Temperature100 × 28%28.0
Flow80 × 22%17.6
Clarity85 × 18%15.3
Feeding Time60 × 13%7.8
Pressure75 × 7%5.3
Insect activity63 × 12%7.6
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.
Directions
Apple MapsGoogle Maps
Seasons & zones
  • Trout 1 January → 31 December
Related guides
Euro Nymphingsubsurface methods
Booking & contacts