Freestone · Mixed · Alps / Savoie (Haute Maurienne)

Arc

Arc venue image
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Major Savoyard alpine river in Haute Maurienne.

Good · Brown Trout
Small Perdigón · 16-20
Goodlive now
A proper day on the water
Low and clear — careful approach country. Stay small, stay accurate.
90% confidence
What moved it
  • LevelDry recentlyNo gauge reading
  • Water temp17.2°C
  • ClarityClear
Today’s fly
Small Perdigón
Small Perdigón16-20
Euro-nymph
Conditions on the water
Estimate
Level
Dry recently
No gauge reading
Water temp17.2°C
ClarityClear
Weather16°C
WindSE 4 km/h
Pressure1021 hPa
Rain · recent0.0 mm
Rain · ahead13.7 mm

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

Water temperature for brown trout
Warm — slow
17°C est.ideal 10–16°C
0°14°28°
How to fish it · for brown trout
When
Through the open trout season — late spring through autumn. The Arc is glacial-fed from Haute Maurienne; fishes once meltwater eases.
Where
Pool tails and pocket water through the Maurienne valley. Glacial Alpine freestone — clear cold water, intimate scale.
Method
Upstream dry to risers; dry-dropper through the riffles. The water reads clear — long leader, fine tippet. Move slowly, cast accurately.
Kit
9 ft #4 — French freestone default. Floating line, 12 ft leader to 4 to 5 lb fluoro. Studded boots.
Why this works
Good — water clarity is right today, though insect activity could be better.
Hatch timeline · todayQuiet day

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

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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
Trout seasonSeason
1
2
2
2
2
2
1
Grayling seasonSeason
1
2
2
2
1
GrannomHatch
2
2
Evening SedgeHatch
2
3
3
3
2
Alpine RhithrogenaHatch
1
2
2
1
Large Dark OliveHatch
1
2
2
1

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.
  • Savoie AAPPMA permits.
What's coming
Plan ahead
5-day outlook
Other water nearby · 5
Arc (Bessans reach)
< 1 km
Brown trout · Grayling
Plan d'Aval
16 km
Brown trout
Tarentaine
19 km
Brown trout · Grayling
Lac du Mont-Cenis
23 km
Brown trout · Char
Isère (Combe de Savoie)
45 km
8
Brown trout · Grayling
Gallery · 1
  1. Terrain map of the venue
    Terrain map
About this water

Major Savoyard alpine river in Haute Maurienne. 7 km no-kill fly-fishing course with barbless-hook requirement. Snowmelt-dominated — May–June best when melt provides volume and insect life emerges. Technical pocket-water fishing in high-alpine terrain on granite freestone. Wild trout in pristine conditions. Check Savoie AAPPMA for permits and regulations.

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

WFD classification · FRDR361A

The full read · show the working · for brown trout · confidence 90%
How the 72 is built — score × weight = contribution
Temperature72 × 28%20.2
Flow60 × 22%13.2
Clarity95 × 18%17.1
Feeding Time70 × 13%9.1
Pressure80 × 7%5.6
Insect activity58 × 12%7.0
Conditions total= 72
Can you trust it?
Water temperatureair-to-water estimateestimated
Level / flowon-river gaugeobserved
Prey activitysurvey-backed invertebrate datasurvey
Directions
Apple MapsGoogle Maps
Seasons & zones
  • Trout2nd Saturday of March → 3rd Sunday of September
  • Grayling3rd Saturday of May → 3rd Sunday of September

    France national rule: grayling opens 3rd Saturday of May in all waters. In 1st category (salmonid) rivers, grayling closes with the trout season on the 3rd Sunday of September. Departmental regulations may impose additional restrictions. Always check the relevant département's 2026 arrêté préfectoral.

Related guides
Grayling Playbookgrayling tacticsPyrenees PlaybookFrench riversEuro Nymphingsubsurface methods
Booking & contacts