Freestone · Granite · Morvan / Nièvre

Yonne (Upper, Morvan Headwaters)

Yonne (Upper, Morvan Headwaters) — Le pont Boffrand-Hupeau - Joigny
Poor · Brown Trout
CDC Emerger · 16-18
New ruleReported 7 Aug 2026

Severe drought restrictions (crise) in force

The ARROUX MORVAN zone (Dept 71) is at crise — 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°37613 ↗

Temporary notices from official orders and recent fishery reports — they clear automatically once out of date.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

Poorlive now
Not the day for it
River temperature is the limiting factor today, not the flow. This is not the day to push it. Check the thermal advice above before you head out.
90% confidence
What moved it
  • LevelProxyvia Sioule
  • Water temp23.6°C
  • ClarityClear
Today's fly
CDC Emerger
CDC Emerger16-18
Dead-drift
Conditions on the water
Proxy gauge
Level
Steady
Proxy
via Sioule
Water temp23.6°C
ClarityClear
Weather35°C
WindSE 10 km/h
Pressure1020 hPa
Rain · recent0.0 mm
Rain · ahead0.0 mm

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

Water temperature for Brown Trout
Warm — slow
24°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
Water at 23.6°C. This is the line where catch-and-release kills brown trout. Do not fish for them today.
Sub-surface · on the nymphunder the surface

Hatch predictions

Top nymph shown — see all 3 guilds with Pro.

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Beyond the hatch · worth watchingambient prey

Hatch predictions

Top prey shown — see all 2 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 · August highlighted
J
F
M
A
M
J
J
A
S
O
N
D
Trout seasonSeason
1
2
2
2
2
2
1
Large Dark OliveHatch
1
2
2
1
Blue Winged OliveHatch
1
2
2
2
2
1
Autumn OliveHatch
1
2
1
GrannomHatch
1
1

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 Château-Chinon / Fédération de la Nièvre
  • 1ère catégorie standard.
What's coming
Plan ahead
5-day outlook
Water here around 24°C. Nothing cooler within range — carry a thermometer.
Gallery · 2
  1. Yonne (Upper, Morvan Headwaters) — Le pont Boffrand-Hupeau - Joigny
    Le pont Boffrand-Hupeau - Joigny
  2. Terrain map of the venue
    Terrain map
Water quality (WFD)
  • Ecology: High
  • Chemical: Failing to achieve good
What this classification means

WFD ecological status Good → High and chemical status Good → Failing to achieve good corrected to EEA WISE 2022 (3rd RBMP) classification for waterbody FRHR42A (was a stale earlier-cycle value). Source: EEA WISE SWB_SurfaceWaterBody (discodata.eea.europa.eu), verified 2026-06-18.

WFD classification · FRHR42A

The full read · show the working · for Brown Trout · confidence 90%
How the 0 is built — score × weight = contribution
Temperature0 × 28%0.0
Flow80 × 22%17.6
Clarity95 × 18%17.1
Feeding Time60 × 13%7.8
Pressure80 × 7%5.6
Insect activity46 × 12%5.5
Limiting factor: Water temperature (23.6°C) is outside Brown Trout's preferred range (10–16°C)= 54
Can you trust it?
Water temperatureair-to-water estimateestimated
Level / flowproxy via Siouleproxy
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
Related guides
Pyrenees PlaybookFrench riversEuro Nymphingsubsurface methods
Booking & contacts