Chalk · Pas-de-Calais / Boulogne-sur-Mer, FR

Liane

Liane boulogne62

The Liane runs about forty kilometres from its source near Quesques down through Samer to Boulogne-sur-Mer, a short coastal chalk stream that most fly anglers have never heard of.

Poor · Brown Trout
Parachute Adams · 14-16
New ruleReported 15 Aug 2026

Severe drought restrictions (alerte renforcée) — angling may be restricted

VigiEau lists this venue's surface-water zone (Bassins versants des fleuves côtiers du Boulonnais, dépt 62) at alerte renforcée, under an official préfectoral drought arrêté. The decree allows angling to be restricted in this zone; check the arrêté and local notices before fishing.

Arrêté préfectoral n°37723 ↗

Temporary notices from official orders and recent fishery reports — they clear automatically once out of date.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
  • LevelProxyvia Scie
  • Water temp17.7°C
  • ClarityClear
Today's fly
Parachute Adams
Parachute Adams14-16
Upstream dry
Conditions on the water
Proxy gauge
Level
Steady
Proxy
via Scie
Water temp17.7°C
ClarityClear
Weather23°C
WindSE 14 km/h
Pressure1015 hPa
Rain · recent5.7 mm
Rain · ahead10.3 mm

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

Water temperature for Brown Trout
Warm — slow
18°C est.ideal 10–16°C
0°14°28°
How to fish it · for Brown Trout
When
Through the open trout season. Olives April through May; sedges through summer evenings.
Where
Pool tails and pocket water through the Boulogne valley. The Liane is small intimate chalk water.
Method
Upstream dry to spotted rising fish; long fine leader. The water reads clear — careful approach matters more than fly choice. Move slowly upstream, cast accurately, accept the result.
Kit
9 ft #4 — French karst-stream default. Floating line, 14 ft leader to 4 lb fluoro. Polarising glasses non-negotiable.
Likely species
Hatch timeline · todayPeak at 11am

Hatch predictions

Today's headline hatch shown — see all 12 active hatches hour by hour as a supporter.

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Sub-surface · on the nymphunder the surface

Hatch predictions

Supporters see the full sub-surface read.

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Beyond the hatch · worth watchingambient prey(1)

Hatch predictions

Top prey shown — see all 4 as a supporter.

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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 · September highlighted
J
F
M
A
M
J
J
A
S
O
N
D
Trout seasonSeason
1
2
2
2
2
2
1
Freshwater ShrimpHatch
2
3
3
3
3
3
3
3
3
3
3
2
Brown SedgeHatch
2
3
3
3
2
Small SpurwingHatch
2
3
3
3
2
Small Dark OliveHatch
2
3
3
3
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 access
  • Sea trout fishing concentrated on lower meadows below Hesdin-l'Abbé — verify permit coverage of the tidal sections.
What's coming
Plan ahead
5-day outlook
Other water nearby · 5
Gallery · 2
  1. Liane boulogne62
  2. Terrain map of the venue
    Terrain map
About this water

The Liane runs about forty kilometres from its source near Quesques down through Samer to Boulogne-sur-Mer, a short coastal chalk stream that most fly anglers have never heard of. The upper half is proper brown trout water — clear, watercressed, rich with olives and sedges — and the lower half, below the tidal limit, gets a genuine sea trout run in late summer and autumn. It's not a famous river and it's not a large one, but it has the things that matter: stable water temperatures, proper fly life, wild fish. The AAPPMA beats around Hesdin-l'Abbé are good value for a day's fishing, and the sea trout fishing in the lower meadows in September, when the water drops and the fish come in on the bigger tides, is the kind of thing you remember.

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)
  • Ecology: Moderate
  • Chemical: Unknown

WFD classification · FRAR30

The full read · show the working · for Brown Trout · confidence 75%
How the 0 is built — score × weight = contribution
Temperature49 × 28%13.7
Flow80 × 22%17.6
Clarity95 × 18%17.1
Feeding Time60 × 13%7.8
Pressure80 × 7%5.6
Insect activity68 × 12%8.2
Conditions total= 70
Can you trust it?
Water temperatureair-to-water estimateestimated
Level / flowproxy via Scieproxy
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 March → 3rd Sunday of September

Sea trout: Variable seasonal (2026)

Related guides
Casting instructors near here
Booking & contacts