Spate · Mixed · Gipuzkoa, País Vasco

Bidasoa

A river weir in the foreground with a Basque village of white houses and a church tower on the far bank, backed by wooded hills

A transnational border river between Spain and France, draining the western Pyrenees with classic mixed-geology spate character.

Poor · Brown Trout
Klinkhammer · 14-18
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.
80% confidence
What moved it
  • Level0.83 m
  • Water temp21.6°C
  • ClarityClear
Today's fly
Klinkhammer
Klinkhammer14-18
High-confidence seasonal pick
Conditions on the water
Live gauge
Level
Steady
0.83 m
lowspate
Water temp21.6°C
ClarityClear
Weather29°C
WindS 23 km/h
Pressure1012 hPa
Rain · recent5.5 mm
Rain · ahead20.1 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
22°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 21.6°C — above the brown trout caution line (18°C). Fish dawn or dusk only. Land it fast, wet hands, no air shots.
Likely species
Gammarids
Hatch timeline · todayQuiet day

Hatch predictions

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Beyond the hatch · worth watchingambient prey(1)

Hatch predictions

Top prey shown — see all 2 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
Sea trout runRun
1
2
1
Trout seasonSeason
1
2
2
2
1
March BrownHatch
2
3
2
Late March BrownHatch
2
3
2
Large Brook DunHatch
2
3
2
Large StoneflyHatch
2
3
2

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.
  • Gipuzkoa fishing licence required
  • Bidasoa border-water rules, named beats, and any cross-border coordination matter more than old salmon-era assumptions, so check the exact section before travel.
What's coming
Plan ahead
5-day outlook
Water here around 22°C. Nothing cooler within range — carry a thermometer.
Gallery · 2
  1. A river weir in the foreground with a Basque village of white houses and a church tower on the far bank, backed by wooded hills
    The Bidasoa river flowing past the village of Sunbilla, Gipuzkoa, in the evening light
  2. Terrain map of the venue
    Terrain map
About this water

A transnational border river between Spain and France, draining the western Pyrenees with classic mixed-geology spate character. In modern practical fly-fishing terms, the Bidasoa should be treated as a trout-and-sea-trout river with strong heritage-salmon identity rather than as a realistic salmon-chasing destination. The 5-hour response time to rainfall still creates excellent post-spate windows, and the lower and middle sections around Bera remain the key structured water.

Hatches & food

In the steep, often pressured Atlantic rivers of the Basque Country, trout opportunities centre on spring olives and other up-wings when flows and colour briefly line up, with caddis and buzzers helping to sustain sport into early and mid-summer, and terrestrials from grassy, wooded margins adding surface food in quieter, recovering reaches.

  • Mixed
Water quality (WFD)
  • Ecology: Good
  • Chemical: Unknown

WFD classification · ES017MSPFES010MAR002420

The full read · show the working · for Brown Trout · confidence 80%
How the 6 is built — score × weight = contribution
Temperature3 × 28%0.8
Flow15 × 22%3.3
Clarity95 × 18%17.1
Feeding Time70 × 13%9.1
Pressure80 × 7%5.6
Insect activity31 × 12%3.7
Limiting factor: Water temperature (21.6°C) is outside Brown Trout's preferred range (10–16°C)= 40
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.
A drop and clear would lift the flow and clarity scores.
Directions
Apple MapsGoogle Maps
Seasons & zones
  • Sea trout 1 May → 31 July
  • Trout third Sunday of March → 31 July

Sea trout: Variable seasonal (2026)

Salmon: Heritage only (2026) — Heritage salmon river. In practical angling terms, salmon are not a target species — focus on trout and sea trout.

Related guides
Pyrenees PlaybookSpanish riversEuro Nymphingsubsurface methods
Booking & contacts