Spate · Granite · Brittany / Côtes-d'Armor

Trieux

A wide panoramic view of the wooded Trieux river valley with the tidal river visible below.
Contributor photo

View over Trieux River from La Roche-Jagu Chateau

Adam Jones - CC BY 2.0

Small Brittany stream with wild trout on Armorican granite.

Poor · Brown Trout
CDC Emerger · 16-18
Poorlive now
Not the day for it
River temperature is the limiting factor today, not the flow. This is not the day to push it. Check the thermal advice above before you head out.
80% confidence
What moved it
  • LevelDry recentlyNo gauge reading
  • Water temp21.7°C
  • ClarityClear
Today’s fly
CDC Emerger
CDC Emerger16-18
Dead-drift
Conditions on the water
Estimate
Level
Dry recently
No gauge reading
Water temp21.7°C
ClarityClear
Weather24°C
WindE 19 km/h
Pressure1018 hPa
Rain · recent0.0 mm
Rain · ahead18.5 mm

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

Water temperature for brown trout
Warm — slow
22°C est.ideal 10–16°C
0°14°28°
How to fish it · for brown trout
When
Through the open trout season. Spring olives and grannom; sedges through summer evenings; small dark flies into autumn close.
Where
Pool tails and the seams behind boulders through the Côtes-d'Armor stretches. Breton spate freestone — fish 12 to 24 hours after rain. The Trieux is a typical Côtes-d'Armor spate — short, sharp, wadeable.
Method
Upstream dry to risers; dry-dropper through the riffles. Breton spate freestone — fish 12 to 24 hours after rain on the drop. Long leader, fine tippet.
Kit
9 ft #4 — Breton spate freestone. Floating line, 12 ft leader to 4 lb fluoro. Studded boots.
Why this works
⚠️ Water at 21.7°C — above the brown trout caution line (18°C). Fish dawn or dusk only. Land it fast, wet hands, no air shots. Otherwise very poor — water clarity is in the right range.
Sub-surface · on the nymphunder the surface

Hatch predictions

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Beyond the hatch · worth watchingambient prey

Hatch predictions

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Evidence
Survey-backed · regionalModerate confidence

Backed by regional invertebrate surveys; no sampling on this exact reach yet.

Through the year
0–3 scale · July highlighted
J
F
M
A
M
J
J
A
S
O
N
D
Salmon runRun
1
2
2
2
2
2
1
Trout seasonSeason
1
2
2
2
2
2
1
March BrownHatch
2
3
2
GrannomHatch
2
2
Large StoneflyHatch
2
3
2
Yellow SallyHatch
2
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.
  • AAPPMA permits.
What's coming
Plan ahead
5-day outlook
Water here around 22°C. Nothing cooler within range — carry a thermometer.
Gallery · 2
  1. A wide panoramic view of the wooded Trieux river valley with the tidal river visible below.
    View over Trieux River from La Roche-Jagu Chateau
  2. Terrain map of the venue
    Terrain map
About this water

Small Brittany stream with wild trout on Armorican granite. Fly-fishing potential for those willing to seek out intimate water. Spring through early autumn. Not crowded — solitude and wild trout are part of the appeal. Check local AAPPMA for access details and any seasonal restrictions.

  • Granite
Water quality (WFD)
  • Ecology: Moderate
  • Chemical: Unknown

WFD classification · FRGR0030B

The full read · show the working · for brown trout · confidence 80%
How the 16 is built — score × weight = contribution
Temperature8 × 28%2.2
Flow60 × 22%13.2
Clarity95 × 18%17.1
Feeding Time55 × 13%7.2
Pressure80 × 7%5.6
Insect activity45 × 12%5.4
Limiting factor: Water temperature (21.7°C) is outside Brown Trout's preferred range (10–16°C)= 51
Can you trust it?
Water temperatureair-to-water estimateestimated
Level / flowon-river gaugeobserved
Prey activitysurvey-backed invertebrate datasurvey
What would change the calculation
Cooler water — back toward the 10–16 °C ideal band — would lift the score and ease welfare.
The dawn and dusk windows score higher than the midday lull.
Directions
Apple MapsGoogle Maps
Seasons & zones
  • Salmon1 March → 15 September
  • Trout2nd Saturday of March → 3rd Sunday of September

Salmon: Banned (2026) — Brittany 2026 order bans Atlantic salmon and sea trout on all Breton rivers.

Sea trout: Banned (2026) — Brittany 2026 order bans Atlantic salmon and sea trout on all Breton rivers.

Related guides
Pyrenees PlaybookFrench riversEuro Nymphingsubsurface methods
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