Freestone · Limestone · Navarra, ES

Río Erro

Río Erro venue image

A pristine Arga tributary in the eastern Pyrenean sector of Navarra, flowing through a compact limestone catchment with high elevation and steep gradients.

Poor · Brown Trout
Klinkhammer · 14-18
Closed season
Out of season. Plenty of other water available now.
Closed — confidence not applicable today.
What moved it
  • LevelProxyvia Río Irati
  • Water temp17.2°C
  • ClarityVery colouredColouring up
Today's fly
Klinkhammer
Klinkhammer14-18
High-confidence seasonal pick
Conditions on the water
Proxy gauge
Level
Steady
Proxy
via Río Irati
Water temp17.2°C
ClarityVery coloured
Weather19°C
WindNE 5 km/h
Pressure1019 hPa
Rain · recent0.0 mm
Rain · ahead2.0 mm

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

Water temperature for Brown Trout
Warm — slow
17°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.
Hatch timeline · todayPeak at 6pm

Hatch predictions

Today's headline hatch shown — see all 11 active hatches hour by hour with Pro.

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Sub-surface · on the nymphunder the surface

Hatch predictions

Top nymph shown — see all 2 guilds with Pro.

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Beyond the hatch · worth watchingambient prey

Hatch predictions

Top prey shown — see all 2 with Pro.

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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 · August highlighted
J
F
M
A
M
J
J
A
S
O
N
D
Trout seasonSeason
1
1
GrannomHatch
2
2
Evening SedgeHatch
2
3
3
3
2
Large Dark OliveHatch
1
2
2
1
Iron BlueHatch
1
2
2
1

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.
  • Gobierno de Navarra fishing licence required
  • Check the exact tramo and any daily-permit or coto-pass requirement for the named stretch before travel.
What's coming
Plan ahead
5-day outlook
Other water nearby · 5
Río Urrobi
9.0 km
0
Brown trout
Río Ulzama
20 km
0
Brown trout
Bidasoa tributaries (Navarra side)
23 km
0
Brown trout · Sea trout
Río Irati
20 km
Brown trout
Río Areta
23 km
Brown trout
Gallery · 1
  1. Terrain map of the venue
    Terrain map
About this water

A pristine Arga tributary in the eastern Pyrenean sector of Navarra, flowing through a compact limestone catchment with high elevation and steep gradients. Clear, cold alpine freestone with pocket water and short pools holding small to medium wild browns. Technical nymphing and dry fly essential — delicate presentation and careful wading. Limestone geology means rapid snowmelt rise and a fast return to base flow.

  • Limestone
Water quality (WFD)
  • Ecology: Good
  • Chemical: Unknown
What this classification means

WFD ecological status High → Good corrected to EEA WISE 2022 (3rd RBMP) classification for waterbody ES091MSPF698 (was a stale earlier-cycle value). Source: EEA WISE SWB_SurfaceWaterBody (discodata.eea.europa.eu), verified 2026-06-18.

WFD classification · ES091MSPF698

The full read · show the working · for Brown Trout · confidence 55%
How the 0 is built — score × weight = contribution
Temperature72 × 28%20.2
Flow80 × 22%17.6
Clarity15 × 18%2.7
Feeding Time75 × 13%9.8
Pressure80 × 7%5.6
Insect activity49 × 12%5.9
Limiting factor: Water is very coloured — too coloured for Brown Trout= 62
Can you trust it?
Water temperatureair-to-water estimateestimated
Level / flowproxy via Río Iratiproxy
Prey activitysurvey-backed invertebrate datasurvey
What would change the calculation
A drop and clear would lift the flow and clarity scores.
Directions
Apple MapsGoogle Maps
Seasons & zones
  • Trout 1 May → 30 June

    RSS Irati–Erro basin (2,728 permits in 2026). All catch-and-release. Extendable to 15 Jul by resolution. Daily basin permit required.

Related guides
Fly Fishing Near Pamplonafeatured in this city guidePyrenees PlaybookSpanish riversEuro Nymphingsubsurface methods
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