Freestone · Granite · Savoie / Alps (Tarentaise valley)

Arc (Bessans reach)

The Arc descends from the high Vanoise through Bessans into a valley where snowmelt and granite are the dominant geology.

Good · Brown Trout
Small Perdigón · 16-20
Goodlive now
A proper day on the water
River steady at a fishable height. A proper day for it. Work the seams with an upstream nymph, switch to the dry when they show.
75% confidence
What moved it
  • Level0.48 mLast reading 1h ago
  • Water temp13.1°C
  • ClarityClear
Today’s fly
Small Perdigón
Small Perdigón16-20
Euro-nymph
Conditions on the water
Live gauge
Level
Steady
0.48 m
Last reading 1h ago
Water temp13.1°C
ClarityClear
Weather13°C
WindSW 1 km/h
Pressure1024 hPa
Rain · recent99.1 mm
Rain · ahead7.5 mm

Live readings — water temperature is an estimate where the gauge does not record it.

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
Good — water temperature is working for you, but insect activity is the limiting factor today.
Hatch timeline · todayQuiet day

Hatch predictions

Today's headline hatch shown — see all 11 active hatches hour by hour with Pro.

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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
Alpine RhithrogenaHatch
2
3
3
2
Sculpin / Baitfish (Rivers)Hatch
2
3
3
3
3
3
3
3
2
Large Dark OliveHatch
1
2
2
1
Blue Winged OliveHatch
1
2
2
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.
  • Alpine AAPPMA permits.
What's coming
Plan ahead
5-day outlook
Other water nearby · 5
Arc
< 1 km
80
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
35
Brown trout · Grayling
About this water

The Arc descends from the high Vanoise through Bessans into a valley where snowmelt and granite are the dominant geology. Short-season alpine water — May and June critical when melt provides volume and insect life emerges. Wild brown trout and grayling in cold, oxygenated freestone. Technical mountain fishing with small dries and nymphs. Check access to beats near Bessans.

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

WFD classification · FRDR10769

The full read · show the working · for brown trout · confidence 75%
How the 79 is built — score × weight = contribution
Temperature100 × 28%28.0
Flow80 × 22%17.6
Clarity95 × 18%17.1
Feeding Time45 × 13%5.9
Pressure80 × 7%5.6
Insect activity44 × 12%5.3
Conditions total= 80
Can you trust it?
Water temperatureair-to-water estimateestimated
Level / flowon-river gaugeobserved
Prey activitysurvey-backed invertebrate datasurvey
What would change the calculation
The dawn and dusk windows score higher than the midday lull.
Directions
Apple MapsGoogle Maps
Seasons & zones
  • Trout2nd Saturday of March → 3rd Sunday of September
  • Grayling3rd Saturday of May → 3rd Sunday of September
Related guides
Grayling Playbookgrayling tacticsPyrenees PlaybookFrench riversEuro Nymphingsubsurface methods
Booking & contacts