Gammarids
- Ecology: Good
- Chemical: Unknown
WFD classification · ES017MSPFES010MAR002420
Rules at a glance
- Public water
- Licence required
Water temperature for Brown Trout
Ideal14°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
Good — water temperature is working for you, but river flow is the limiting factor today.
Likely species
Hatch timeline · todayQuiet day
Hatch predictions
Today's headline hatch shown — see all 9 active hatches hour by hour as a supporter.
Start free trial14-day free trial. Cancel anytime.
Sub-surface · on the nymphunder the surface
Hatch predictions
Supporters see the full sub-surface read.
Start free trial14-day free trial. Cancel anytime.
Evidence
Survey-backed · regionalHigh confidence
Backed by regional invertebrate surveys; no sampling on this exact reach yet.
Through the year
0–3 scale · October 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
Fly box · Brown Trout
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
Other water nearby · 5
Gallery · 2
The Bidasoa river flowing past the village of Sunbilla, Gipuzkoa, in the evening light Terrain map
Water quality (WFD)
The full read · show the working · for Brown Trout · confidence 75%
How the 72 is built — score × weight = contribution
Temperature100 × 28%28.0
Flow40 × 22%8.8
Clarity95 × 18%17.1
Feeding Time55 × 13%7.2
Pressure80 × 7%5.6
Insect activity46 × 12%5.5
Conditions total= 72
Can you trust it?
Water temperatureair-to-water estimateestimated
Level / flowon-river gaugeobserved
Prey activitysurvey-backed invertebrate datasurvey
What would change the calculation
The dawn and dusk windows score higher than the midday lull.
Directions
Seasons & zones
- Sea trout 1 May → 31 July
- Trout dritter Sunday im 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
Booking & contacts
Bidasoa
Water temperature for Brown Trout
Ideal14°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
Good — water temperature is working for you, but river flow is the limiting factor today.
Likely species
Hatch timeline · todayQuiet day
Hatch predictions
Today's headline hatch shown — see all 9 active hatches hour by hour as a supporter.
Start free trial14-day free trial. Cancel anytime.
Sub-surface · on the nymphunder the surface
Hatch predictions
Supporters see the full sub-surface read.
Start free trial14-day free trial. Cancel anytime.
Evidence
Survey-backed · regionalHigh confidence
Backed by regional invertebrate surveys; no sampling on this exact reach yet.
Through the year
0–3 scale · October 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
Fly box · Brown Trout
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
Other water nearby · 5
Gallery · 2
The Bidasoa river flowing past the village of Sunbilla, Gipuzkoa, in the evening light Terrain map
Water quality (WFD)
- Ecology: Good
- Chemical: Unknown
WFD classification · ES017MSPFES010MAR002420
The full read · show the working · for Brown Trout · confidence 75%
How the 72 is built — score × weight = contribution
Temperature100 × 28%28.0
Flow40 × 22%8.8
Clarity95 × 18%17.1
Feeding Time55 × 13%7.2
Pressure80 × 7%5.6
Insect activity46 × 12%5.5
Conditions total= 72
Can you trust it?
Water temperatureair-to-water estimateestimated
Level / flowon-river gaugeobserved
Prey activitysurvey-backed invertebrate datasurvey
What would change the calculation
The dawn and dusk windows score higher than the midday lull.
Directions
Seasons & zones
- Sea trout 1 May → 31 July
- Trout dritter Sunday im 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
Booking & contacts