Freestone · Chalk · Île-de-France / Seine-et-Marne and Marne (above La Ferté-Gaucher), FR

Grand Morin (Upper)

Grand Morin Ferté Gaucher 1

The upper Grand Morin is the obvious 1ère catégorie candidate for a Paris-based fly angler — classified as first-category water upstream of the Moulin de Montblin at La Ferté-Gaucher.

Poor · Brown Trout
Pheasant Tail Nymph · 14-18
New ruleReported 27 Aug 2026

Severe drought restrictions (alerte renforcée) in force

VigiEau lists this venue's surface-water zone (Bassin du Grand Morin, dépt 77) at alerte renforcée, under an official préfectoral drought arrêté. Fishing is not itself banned by it, but water levels are low — go gently on stressed fish.

Arrêté préfectoral n°37885 ↗

Temporary notices from official orders and recent fishery reports — they clear automatically once out of date.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

Closed season
Out of season. Try elsewhere.
Closed — confidence not applicable today.
What moved it
  • LevelModerate rain recentlyNo gauge reading
  • Water temp13.2°C
  • ClarityClear
Today's fly
Pheasant Tail Nymph
Pheasant Tail Nymph14-18
Upstream
Conditions on the water
Estimate
Level
Moderate rain recently
No gauge reading
Water temp13.2°C
ClarityClear
Weather8°C
WindSW 17 km/h
Pressure1022 hPa
Rain · recent11.9 mm
Rain · ahead2.5 mm

No gauge on this water — readings are regional estimates from weather, not a live gauge.

Water temperature for Brown Trout
Ideal
13°C est.ideal 10–16°C
0°14°28°
How to fish it · for Brown Trout
When
From the 2nd Saturday of March opening into early September. Best window April–June with small olives and grannom; shoulder through summer.
Where
Upper reaches around La Ferté-Gaucher and upstream towards Esternay. Pool tails, faster glides, and the seams behind overhanging willow on the smaller upper beats.
Method
Upstream dry to risers; dry-dropper through the riffles. Walk-and-spot.
Kit
9 ft #4 (or 8 ft #3 on tighter beats), floating line, 12 ft leader to 3–4 lb fluoro.
Likely species
Gammarids
Hatch timeline · todayQuiet day

Hatch predictions

Today's headline hatch shown — see all 11 active hatches hour by hour as a supporter.

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Sub-surface · on the nymphunder the surface

Hatch predictions

Top nymph shown — see all 2 guilds as a supporter.

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Beyond the hatch · worth watchingambient prey(1)

Hatch predictions

Supporters see what else is on the menu.

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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 · October highlighted
J
F
M
A
M
J
J
A
S
O
N
D
Trout seasonSeason
1
2
2
2
2
2
1
Evening SedgeHatch
2
3
3
3
2
Large Dark OliveHatch
1
2
2
1
Iron BlueHatch
1
2
2
2
2
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

More balanced than the mountain-river pack. French nymphing still matters, but there is more room for dries, spiders and general searching flies.

Permits & access
Permit required — see local rules.
  • 1ère catégorie above Moulin de Montblin (La Ferté-Gaucher)
  • AAPPMA permit + carte de pêche required
  • Check the Seine-et-Marne federation's annual notice for category boundaries, catch limits and method restrictions.
What's coming
Plan ahead
5-day outlook
Other water nearby · 2
Étang BEP22 (Chessy)
41 km
Rainbow trout
Domaine de Coyolles
54 km
Rainbow trout · Brown trout
Gallery · 2
  1. Grand Morin Ferté Gaucher 1
  2. Terrain map of the venue
    Terrain map
About this water

The upper Grand Morin is the obvious 1ère catégorie candidate for a Paris-based fly angler — classified as first-category water upstream of the Moulin de Montblin at La Ferté-Gaucher. Above that boundary the river fishes as a small chalk-leaning stream through Esternay and the eastern Seine-et-Marne / Marne countryside; below it slides into the more mixed, coarse-fish water that defines most of the regional rivers. Modest stream trout in modest numbers under modest pressure. Travel with images of the Andelle or the Risle in your head and you will be disappointed; travel with low expectations and a willingness to enjoy small fish in a small river, and the upper Grand Morin is a sound way to spend a morning.

  • Chalk
The full read · show the working · for Brown Trout · confidence 90%
How the 0 is built — score × weight = contribution
Temperature100 × 28%28.0
Flow80 × 22%17.6
Clarity95 × 18%17.1
Feeding Time70 × 13%9.1
Pressure80 × 7%5.6
Insect activity61 × 12%7.3
Conditions total= 85
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
Related guides
Pyrenees PlaybookFrench riversEuro Nymphingsubsurface methods
Booking & contacts