Chalk · Normandy / Seine-Maritime (Coastal chalk stream)

Durdent

A historic stone watermill with a large wooden waterwheel, with the Durdent River flowing past in the foreground.

Small Normandy chalk stream with quiet character and consistent flow.

Poor · Brown Trout
Spent Spinner · 16-20
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
  • Level0.26 mLast reading 1d ago
  • Water temp23.1°C
  • ClarityClear
Today's fly
Spent Spinner
Spent Spinner16-20
Upstream dry
Conditions on the water
Live gauge
Level
Steady
0.26 m
Last reading 1d ago
Water temp23.1°C
ClarityClear
Weather34°C
WindN 8 km/h
Pressure1021 hPa
Rain · recent0.0 mm
Rain · ahead0.4 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
23°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 23.1°C. This is the line where catch-and-release kills brown trout. Do not fish for them today.
Beyond the hatch · worth watchingambient prey

Hatch predictions

Top prey shown — see all 3 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
Grayling seasonSeason
1
2
2
2
2
2
2
1
Brown SedgeHatch
2
3
2
Freshwater ShrimpHatch
2
3
3
3
3
3
3
3
3
3
3
2
Blue Winged OliveHatch
2
3
3
3
3
2
Mayfly (Green Drake)Hatch
2
2

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

Ranked for today
Brown Trout fly box

Classic French chalkstream fishing. Gin-clear, weed-rich, slow to moderate flow. Dry fly and sight nymphing dominate. Stronger sedge hatches than English equivalents. French tradition favours flush-sitting dries (comparaduns, CDC patterns) and upstream presentation.

Permits & access
Permit required — see local rules.
  • AAPPMA permits.
What's coming
Plan ahead
5-day outlook
Water here around 23°C. Nothing cooler within range — carry a thermometer.
Gallery · 2
  1. A historic stone watermill with a large wooden waterwheel, with the Durdent River flowing past in the foreground.
    Vieux moulin/Old Mill, Normandy-France
  2. Terrain map of the venue
    Terrain map
About this water

Small Normandy chalk stream with quiet character and consistent flow. Wild brown trout and grayling respond to seasonal insect patterns. Clear water, stable temperature typical of chalk geology. Small flies required: olives and ephemeralids (16–18), sedges (14–16) in evening. Presentation matters more than fly choice. Some stretches private. Check access with local club.

Hatches & food

In chalk-spring and karst trout systems, generally stable temperatures broaden olive and other mayfly activity from early spring into autumn, with strong evening caddis, steady subsurface scuds and buzzers where clear groundwater and weedbeds develop, and terrestrials from meadow and woodland banks rounding out the food calendar, depending on how fast each river drops and clears after rain.

  • Chalk
Water quality (WFD)
  • EcologyGood
  • ChemicalUnknown

WFD classification · FRHR171

The full read · show the working · for Brown Trout · confidence 90%
How the 2 is built — score × weight = contribution
Temperature1 × 28%0.3
Flow80 × 22%17.6
Clarity95 × 18%17.1
Feeding Time60 × 13%7.8
Pressure80 × 7%5.6
Insect activity49 × 12%5.9
Limiting factor: Water temperature (23.1°C) is outside Brown Trout's preferred range (10–16°C)= 54
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
Seasons & zones
  • Trout 2nd Saturday of March3rd Sunday of September
  • Grayling 3rd Saturday of May31 December

    France national rule: grayling opens 3rd Saturday of May in all waters. In 2nd category waters, grayling remains open until 31 December. Departmental regulations may impose earlier closing dates. Always check the relevant département's 2026 arrêté préfectoral.

Related guides
Booking & contacts