Freestone · Limestone · Alps / Savoie-Isère border

Guiers

Guiers terrain map
Terrain map

1st-category river on the Savoie-Isère border with ~1.

Prime · Brown Trout
Small Perdigón · 16-20
Primelive now
About as good as it gets
River dropping into shape after a lift. The kind of afternoon you remember — a weighted nymph through the clearing seams, the dry as it settles.
90% confidence
What moved it
  • Level0.74 mDropping after lift
  • Water temp16.0°C
  • ClarityClear
Today’s fly
Small Perdigón
Small Perdigón16-20
Euro-nymph
Conditions on the water
Live gauge
Level
Steady
0.74 m
Dropping after lift
Water temp16.0°C
ClarityClear
Weather20°C
WindS 3 km/h
Pressure1022 hPa
Rain · recent0.8 mm
Rain · ahead7.7 mm

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

Water temperature for brown trout
Ideal
16°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
Excellent — water temperature is right today, though time of day could be better.
Hatch timeline · todayQuiet day

Hatch predictions

Today's headline hatch shown — see all 10 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
March BrownHatch
2
3
2
Large StoneflyHatch
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
Other water nearby · 5
Gelon
11 km
75
Brown trout · Grayling
Isère (Combe de Savoie)
21 km
Brown trout · Grayling
Lac d'Aiguebelette
25 km
Brown trout · Char
Lac du Bourget
39 km
Brown trout · Char
Tarentaine
46 km
Brown trout · Grayling
About this water

1st-category river on the Savoie-Isère border with ~1.5 km no-kill course through limestone and alpine terrain where geology changes hands. Selective dry-fly water in pristine conditions. Spring through early autumn offers consistent fishing. Mountain character with responsive flow. Some sections may have specific regulations; verify with local AAPPMA.

  • Limestone
Water quality (WFD)
  • Ecology: Moderate
  • Chemical: Unknown
What this classification means

WFD ecological status Poor → Moderate corrected to EEA WISE 2022 (3rd RBMP) classification for waterbody FRDR515 (was a stale earlier-cycle value). Source: EEA WISE SWB_SurfaceWaterBody (discodata.eea.europa.eu), verified 2026-06-18.

WFD classification · FRDR515

The full read · show the working · for brown trout · confidence 90%
How the 83 is built — score × weight = contribution
Temperature100 × 28%28.0
Flow80 × 22%17.6
Clarity95 × 18%17.1
Feeding Time55 × 13%7.2
Pressure80 × 7%5.6
Insect activity64 × 12%7.7
Conditions total= 83
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