Spate · Granite · Brittany / Finistère (Quimper)

Jet

The Jet river in spate flowing over a weir, Ergué-Gabéric, Finistère
Contributor photo

The Jet river at Ergué-Gabéric, near Quimper

GdTerrier

Small Quimper-area trout river with deep holes holding good trout.

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
  • LevelLight rain recentlyNo gauge reading
  • Water temp21.6°C
  • ClarityClear
Today’s fly
CDC Emerger
CDC Emerger16-18
Dead-drift
Conditions on the water
Estimate
Level
Light rain recently
No gauge reading
Water temp21.6°C
ClarityClear
Weather20°C
WindNE 10 km/h
Pressure1017 hPa
Rain · recent5.1 mm
Rain · ahead22.7 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
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
⚠️ Water at 21.6°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.
Hatch timeline · todayPeak at 6pm

Hatch predictions

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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.
  • Carte de pêche AAPPMA.
What's coming
Plan ahead
5-day outlook
Water here around 22°C. Nothing cooler within range — carry a thermometer.
Gallery · 2
  1. The Jet river in spate flowing over a weir, Ergué-Gabéric, Finistère
    The Jet river at Ergué-Gabéric, near Quimper
  2. Terrain map of the venue
    Terrain map
About this water

Small Quimper-area trout river with deep holes holding good trout. Some sea trout possibility in lower sections. Armorican granite geology. Fly-fishing opportunity. Intimate water, not high-volume, but worthwhile for those seeking quiet and wild fish. Spring through early summer best. Check local AAPPMA for access and regulations.

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

WFD classification · FRGR0083

The full read · show the working · for brown trout · confidence 80%
How the 17 is built — score × weight = contribution
Temperature9 × 28%2.5
Flow80 × 22%17.6
Clarity95 × 18%17.1
Feeding Time40 × 13%5.2
Pressure80 × 7%5.6
Insect activity44 × 12%5.3
Limiting factor: Water temperature (21.6°C) is outside Brown Trout's preferred range (10–16°C)= 53
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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