Freestone · Limestone · Navarra

Río Erro

Río Erro venue image
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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 temp12.8°C
  • ClarityClear
Today’s fly
Klinkhammer
Klinkhammer14-18
High-confidence seasonal pick
Conditions on the water
Proxy gauge
Level
Steady
Proxy
via Río Irati
Water temp12.8°C
ClarityClear
Weather13°C
WindN 21 km/h
Pressure1027 hPa
Rain · recent0.2 mm
Rain · ahead4.4 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
Ideal
13°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 · todayQuiet day

Hatch predictions

Today's headline hatch shown — see all 10 active hatches hour by hour with Pro.

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Evidence
Records-basedModerate confidence

Based on species-occurrence records, not local invertebrate surveys.

Through the year
0–3 scale · July 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 Ulzama
20 km
0
Brown trout
Bidasoa tributaries (Navarra side)
23 km
0
Brown trout · Sea trout
Río Urrobi
9.0 km
Brown 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 75%
How the 0 is built — score × weight = contribution
Temperature100 × 28%28.0
Flow80 × 22%17.6
Clarity95 × 18%17.1
Feeding Time40 × 13%5.2
Pressure80 × 7%5.6
Insect activity53 × 12%6.4
Conditions total= 80
Can you trust it?
Water temperatureair-to-water estimateestimated
Level / flowproxy via Río Iratiproxy
Prey activitymodelled from regional profilemodelled
What would change the calculation
The dawn and dusk windows score higher than the midday lull.
Directions
Apple MapsGoogle Maps
Seasons & zones
  • Trout1 May → 30 June
Related guides
Pyrenees PlaybookSpanish riversEuro Nymphingsubsurface methods
Booking & contacts