Freestone · Mixed · Haute-Savoie

Nom

A rushing forest river, the Nom, flowing over rocks and fallen branches through golden autumn trees near Thones, Haute-Savoie, France.

The Nom is the river you fish when you want to remember why you started doing this in the first place.

Marginal · Brown Trout
Small Perdigón · 16-20
New ruleReported 1 Aug 2026

Severe drought restrictions (alerte renforcée) in force

The Arve aval zone (Dept 74) is at alerte renforcée — the second-highest French drought tier — under a préfectoral arrêté. Fishing itself is not named as prohibited, but water is severely restricted and flows are likely very low; fish with care and check locally.

Arrêté préfectoral n°37507

Temporary notices from official orders and recent fishery reports — they clear automatically once out of date.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

Marginallive now
Slow going — pick your moments
River temperature is the limiting factor today, not the flow. Fish dawn or dusk if you go at all, and handle everything with extra care.
80% confidence
What moved it
  • LevelProxyvia Borne
  • Water temp19.6°C
  • ClarityVery colouredColouring up
Today's fly
Small Perdigón
Small Perdigón16-20
Euro-nymph
Conditions on the water
Proxy gauge
Level
Rising
Proxy
via Borne
Water temp19.6°C
ClarityVery coloured
Weather22°C
WindSE 7 km/h
Pressure1019 hPa
Rain · recent0.0 mm
Rain · ahead5.3 mm

No gauge on this water — conditions are inferred from Borne. The trend transfers, the absolute level does not.

Water temperature for Brown Trout
Warm — slow
20°C est.ideal 1016°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
Water at 19.6°C — above the brown trout caution line (18°C). Fish dawn or dusk only. Land it fast, wet hands, no air shots.
Hatch timeline · todayPeak at 6pm

Hatch predictions

Today's headline hatch shown — see all 9 active hatches hour by hour with Pro.

Start free trial

14-day free trial. Cancel anytime.

Sub-surface · on the nymphunder the surface

Hatch predictions

See the full sub-surface read with Pro.

Start free trial

14-day free trial. Cancel anytime.

Beyond the hatch · worth watchingambient prey

Hatch predictions

Top prey shown — see all 2 with Pro.

Start free trial

14-day free trial. Cancel anytime.

Evidence
Survey-backed · regionalModerate 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
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

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

What's coming
Plan ahead
5-day outlook
Cooler water nearby · 1
Water here around 20°C — probably warm enough to stress Brown Trout . These are likely cooler.
Gallery · 2
  1. A rushing forest river, the Nom, flowing over rocks and fallen branches through golden autumn trees near Thones, Haute-Savoie, France.
    Le Nom @ Circuit Jean-Jacques Rousseau @ Thones
  2. Terrain map of the venue
    Terrain map
About this water

The Nom is the river you fish when you want to remember why you started doing this in the first place. It's small — small enough that the far bank is sometimes your own bank a few yards upstream — and it holds wild brown trout that have never seen a stocked fish and don't want to. You'll kneel more than you cast. You'll curse the overhanging branches. And somewhere around mid-morning, if the light is right and the olives are coming off, you'll drop a size 16 into the right seam and watch a six-inch trout materialise from a slick of water you'd have sworn was empty. Short rods, long leaders, light tippet — nothing else will fit. Spring snowmelt keeps it running cold into June, and by July the low-water trout become properly suspicious, which is, of course, the point.

  • Mixed
Water quality (WFD)
  • EcologyModerate
  • ChemicalUnknown
What this classification means

WFD ecological status Good → Moderate corrected to EEA WISE 2022 (3rd RBMP) classification for waterbody FRDR539B (was a stale earlier-cycle value). Source: EEA WISE SWB_SurfaceWaterBody (discodata.eea.europa.eu), verified 2026-06-18.

WFD classification · FRDR539B

The full read · show the working · for Brown Trout · confidence 80%
How the 30 is built — score × weight = contribution
Temperature30 × 28%8.4
Flow55 × 22%12.1
Clarity15 × 18%2.7
Feeding Time80 × 13%10.4
Pressure80 × 7%5.6
Insect activity51 × 12%6.1
Limiting factor: Water is very coloured — too coloured for Brown Trout= 45
Can you trust it?
Water temperatureair-to-water estimateestimated
Level / flowproxy via Borneproxy
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.
A drop and clear would lift the flow and clarity scores.
Directions
Seasons & zones
  • Trout 2nd Saturday of March3rd Sunday of September
Related guides
Booking & contacts
Clubs & associations