Freestone · Limestone · Alps / Savoie-Isère border, FR

Guiers

A clear mountain stream flowing through the village of Saint-Pierre-dEntremont with alpine peaks behind, on the Guiers river system
Good · Brown Trout
Small Perdigón · 16-20
New ruleReported 20 Aug 2026

Severe drought restrictions (alerte renforcée) in force

A préfectoral drought order places this catchment's surface water at alerte renforcée, the second-highest of France's four restriction tiers. Fishing itself is not named in the order, but flows are low and water-use restrictions are in force. Zone: Belledonne (dépt 38).

Arrêté préfectoral n°37806 ↗

Temporary notices from official orders and recent fishery reports — they clear automatically once out of date. Always confirm locally before travelling.

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.
90% confidence
What moved it
  • Level0.63 mLast reading 19h ago
  • Water temp17.4°C
  • ClarityClear
Today's fly
Small Perdigón
Small Perdigón16-20
Euro-nymph
Conditions on the water
Live gauge
Level
Steady
0.63 m
Last reading 19h ago
Water temp17.4°C
ClarityClear
Weather19°C
WindNW 6 km/h
Pressure1017 hPa
Rain · recent12.0 mm
Rain · ahead3.7 mm

The nearest gauge doesn't record temperatures, so we've estimated it — defer to the river keeper's advice.

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
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 clarity is right today, though water temperature could be better.
Hatch timeline · todayQuiet day

Hatch predictions

Today's headline hatch shown — see all 6 active hatches hour by hour with Pro.

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Sub-surface · on the nymphunder the surface

Hatch predictions

Top nymph shown — see all 4 guilds with Pro.

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Beyond the hatch · worth watchingambient prey(1)

Hatch predictions

Top prey shown — see all 3 with Pro.

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Evidence
Survey-backed · regionalHigh confidence

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

Through the year
0–3 scale · August 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
Late March BrownHatch
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
Other water nearby · 5
Gelon
11 km
24
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
Pisciculture de Burcin - La pêche pour tous
45 km
Rainbow trout
Gallery · 2
  1. A clear mountain stream flowing through the village of Saint-Pierre-dEntremont with alpine peaks behind, on the Guiers river system
    The Guiers Vif at Saint-Pierre-d'Entremont, on the Savoie–Isère border
  2. Terrain map of the venue
    Terrain map
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 71 is built — score × weight = contribution
Temperature56 × 28%15.7
Flow80 × 22%17.6
Clarity95 × 18%17.1
Feeding Time60 × 13%7.8
Pressure80 × 7%5.6
Insect activity63 × 12%7.6
Conditions total= 71
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
  • Trout 2nd Saturday of March → 3rd Sunday of September
  • Grayling 3rd 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