Karst · Limestone · Franche-Comté / Doubs (St-Hippolyte)

Dessoubre

Dessoubre venue image
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The Dessoubre is what you end up talking about after a few glasses of wine at the gîte, because you've run out of polite things to say about the Loue.

Poor · Brown Trout
CDC Emerger · 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
  • LevelDry recentlyNo gauge reading
  • Water temp22.0°C
  • ClarityClear
Today’s fly
CDC Emerger
CDC Emerger16-20
Dead-drift
Conditions on the water
Estimate
Level
Dry recently
No gauge reading
Water temp22.0°C
ClarityClear
Weather21°C
WindS 10 km/h
Pressure1016 hPa
Rain · recent0.8 mm
Rain · ahead6.4 mm

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

Water temperature for brown trout
Warm — slow
22°C est.ideal 1016°C
0°14°28°
How to fish it · for brown trout
When
Through the open trout season. Spring olives and sedges; summer evening hatches; autumn small flies into the close.
Where
Limestone gorge water through the Doubs department. Pool tails and the cushion behind boulders; the Dessoubre is small-scale and intimate.
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.
Why this works
⛔ Water at 22°C. This is the line where catch-and-release kills brown trout. Do not fish for them today.
Hatch timeline · todayQuiet day

Hatch predictions

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Sub-surface · on the nymphunder the surface

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Beyond the hatch · worth watchingambient prey

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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 · July 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
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
Gammarus Scud (Olive)
Gammarus Scud (Olive)
12-16 · Gammarus Scud
Dead-drift, sub-surface
Permits & access
Permit required — see local rules.
  • AAPPMA du Dessoubre
  • Fly-only parcours on several stretches, barbless recommended
  • Check current rules — the river has active no-kill reserves.
What's coming
Plan ahead
5-day outlook
Cooler water nearby · 1
Probably above the brown trout safety line — these are likely cooler, but carry a thermometer.
Gallery · 1
  1. Terrain map of the venue
    Terrain map
About this water

The Dessoubre is what you end up talking about after a few glasses of wine at the gîte, because you've run out of polite things to say about the Loue. It rises cold and clean out of the Jura plateau, runs for forty-odd kilometres through a steep limestone valley, and joins the Doubs at St-Hippolyte having done almost everything right. The trout are wild, the grayling are properly big, and the hatches are dense enough to make you grateful you brought reading glasses for your fly box. It was hit hard in the early 2000s by the same mix of agricultural runoff and mysterious fish-kill events that savaged the Loue, and the river still has its difficult days. But when it's on — a cool May morning with BWOs coming off a flat glide — it's as good as continental Europe gets, and you leave promising yourself you'll tell no one about it.

  • Limestone
Water quality (WFD)
  • EcologyGood
  • ChemicalUnknown

WFD classification · FRDR634

The full read · show the working · for brown trout · confidence 90%
How the 12 is built — score × weight = contribution
Temperature6 × 28%1.7
Flow60 × 22%13.2
Clarity95 × 18%17.1
Feeding Time40 × 13%5.2
Pressure80 × 7%5.6
Insect activity48 × 12%5.8
Limiting factor: Water temperature (22°C) is outside Brown Trout's preferred range (10–16°C)= 49
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
  • Trout2nd Saturday of March → 3rd Sunday of September
  • Grayling3rd Saturday of May → 3rd Sunday of September

    France national rule: grayling opens 3rd Saturday of May in all waters. In 1st category (salmonid) rivers, grayling closes with the trout season on the 3rd Sunday of September. Departmental regulations may impose additional restrictions. Always check the relevant département's 2026 arrêté préfectoral.

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