Freestone · Mixed · Alps / Savoie (Cœur de Savoie), FR

Gelon

Le Gelon à Chamousset (été 2019)

AAPPMA-managed tributary of the Isère at Valgelon–La Rochette.

Tomorrow · Closed season
Czech Nymph
Forecast · Tomorrow
Closed season
Out of season. Try elsewhere.
45% projected
Today's fly
Czech Nymph
Czech Nymph
Conditions on the water · Tomorrow
Live gauge
Level
Rising
0.18 m
Lifting fast
Water temp9.4°C
ClarityUnfishable
Weather8°C
WindN 4 km/h
Pressure1015 hPa
Rain · recent27.9 mm
Rain · ahead7.2 mm

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

Water temperature for Grayling
Ideal
9°C est.ideal 4–14°C
0°14°28°
How to fish it · for Grayling
When
Midday window — grayling feed best from late morning into early afternoon.
Where
Work runs and glides — grayling shoal in the bottom third of the water column.
Method
Tight-line nymph the bottom third with weighted patterns.
Kit
10 ft #3 rod, floating line, long leader to 4 lb fluoro for nymphs.
Likely species
Stoneflies
Hatch timeline · tomorrowPeak at 12pm

12pm(now) — Autumn Olive

Stage: On emergersApproach: Emerger or dryActivity: 24%
Also:Autumn Needle Fly21%

Peak activity at 12pm — Autumn Olive

Sub-surface · on the nymphunder the surface

Hatch predictions

Top nymph shown — see all 3 guilds as a supporter.

Start free trial

14-day free trial. Cancel anytime.

Beyond the hatch · worth watchingambient prey(1)

Hatch predictions

Supporters see what else is on the menu.

Start free trial

14-day free trial. Cancel anytime.

Evidence
Survey-backed · regionalHigh confidence

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

Through the year
0–3 scale · November 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
Evening SedgeHatch
2
3
3
3
2
Alpine RhithrogenaHatch
1
2
2
1
Large Dark OliveHatch
1
2
2
1
Iron BlueHatch
1
2
2
2
2
2
2
1

Numbers are intensity 0 (none) to 3 (peak) — a guide, not a guarantee.

Ranked for today
Grayling fly box

French nymph-first water. Fast current, technical presentation, weighted nymphs and emergers, with dry flies when fish rise.

Small Perdigón
Small Perdigón
Hook 14–18 · Fly
in season
Permits & access
Permit required — see local rules.
  • AAPPMA permits.
What's coming
Plan ahead
5-day outlook
Other water nearby · 5
Isère (Combe de Savoie)
11 km
0
Brown trout · Grayling
Guiers
30 km
0
Brown trout · Grayling
Lac d'Aiguebelette
27 km
Brown trout · Char
Lac du Bourget
36 km
Brown trout · Char
Lac d'Annecy
44 km
Brown trout · Char
Gallery · 2
  1. Le Gelon à Chamousset (été 2019)
  2. Terrain map of the venue
    Terrain map
About this water

Trout upstream, grayling in lower reaches. Alpine freestone on granite terrain. Spring through early autumn fishing. Mountain water with responsive character. Check local regulations for any restrictions or parcours requirements.

Hatches & food

In true Alpine headwaters, trout feeding is squeezed into a short high-summer slot, with mountain olives and other mayflies following snowmelt, daytime stoneflies over rough, bouldery water, evening caddis on the warmest settled nights, and small buzzers keeping fish interested before, between and after the main up-wing and caddis hatches.

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

WFD ecological status Good → Moderate corrected to EEA WISE 2022 (3rd RBMP) classification for waterbody FRDR10107 (was a stale earlier-cycle value). Source: EEA WISE SWB_SurfaceWaterBody (discodata.eea.europa.eu), verified 2026-06-18.

WFD classification · FRDR10107

The full read · show the working · for Grayling · confidence 90%
How the 0 is built — score × weight = contribution
Temperature100 × 28%28.0
Flow95 × 22%20.9
Clarity90 × 18%16.2
Feeding Time80 × 13%10.4
Pressure80 × 7%5.6
Insect activity63 × 12%7.6
Conditions total= 89
Can you trust it?
Water temperatureair-to-water estimateestimated
Level / flowon-river gaugeobserved
Prey activitysurvey-backed invertebrate datasurvey
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
At a glance

Gelon is a freestone river in Alps / Savoie (Cœur de Savoie), France. It sits at about 344 m above sea level. The river is described as roughly 30 km long. Species listed for this water: brown trout and grayling. The trout season is recorded as running from 2nd Saturday of March to 3rd Sunday of September. The grayling season is recorded as running from 3rd Saturday of May to 3rd Sunday of September. Best window recorded for anglers: June–September. Core methods listed: Nymphing; dry fly. Level and flow data for this water is linked from 1 gauge. Its recorded parent river is the Isere Savoie. Its Water Framework Directive ecological status is recorded as moderate. Access is recorded as day tickets through the local AAPPMA (angling association). Nearby waters in our listings include Isère (Combe de Savoie) at 11 km, Lac d'Aiguebelette at 27 km and Guiers at 30 km.