Freestone · Limestone · Navarra

Río Erro

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

Closed season

Out of season. Plenty of other water available now.

Closed — confidence not applicable today.

Notify when prime

What moved it

LevelProxyvia Río Irati
Water temp22.8°C
ClarityVery colouredColouring up

Today's fly

Klinkhammer14-18

High-confidence seasonal pick

Live now

Conditions on the water

Proxy gauge

Trends shown where the gauge supports them

Level

Steady

Proxy

via Río Irati

Water temp

22.8°C

coldwarm

Clarity

Very coloured

Colouring up

Weather

33°C

Clear

Wind

S 12 km/h

calmblown out

Pressure

1021 hPa

lowhigh

Rain · recent

0.0 mm

dryspate risk

Rain · ahead

7.1 mm

dryspate risk

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

23°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 22.8°C. This is the line where catch-and-release kills brown trout. Do not fish for them today.

Hatch timeline · todayPeak at 6pm

Hatch predictions

Today's headline hatch shown — see all 5 active hatches hour by hour with Pro.

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14-day free trial. Cancel anytime.

Sub-surface · on the nymphunder the surface

Hatch predictions

See the full sub-surface read with Pro.

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14-day free trial. Cancel anytime.

Beyond the hatch · worth watchingambient prey

Hatch predictions

See what else is on the menu 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

Trout season

Grannom

Evening Sedge

Large Dark Olive

Iron Blue

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

Water here around 23°C. Nothing cooler within range — carry a thermometer.

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 90%

How the 0 is built — score × weight = contribution

Temperature2 × 28%0.6

Flow80 × 22%17.6

Clarity15 × 18%2.7

Feeding Time60 × 13%7.8

Pressure80 × 7%5.6

Insect activity41 × 12%4.9

Limiting factor: Water temperature (22.8°C) is outside Brown Trout's preferred range (10–16°C)= 39

Can you trust it?

Water temperatureair-to-water estimateestimated

Level / flowproxy via Río Iratiproxy

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.

The dawn and dusk windows score higher than the midday lull.

Directions

Apple Maps Google 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

Booking & contacts

Freestone · Limestone · Navarra

Río Erro

Terrain map

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.

Notify when prime

What moved it

LevelProxyvia Río Irati
Water temp22.8°C
ClarityVery colouredColouring up

Today's fly

Klinkhammer14-18

High-confidence seasonal pick

Conditions on the water

Proxy gauge

Level

Steady

Proxy

via Río Irati

Water temp22.8°C

ClarityVery coloured

Weather33°C

WindS 12 km/h

Pressure1021 hPa

Rain · recent0.0 mm

Rain · ahead7.1 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

23°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 22.8°C. This is the line where catch-and-release kills brown trout. Do not fish for them today.

Hatch timeline · todayPeak at 6pm

Hatch predictions

Today's headline hatch shown — see all 5 active hatches hour by hour with Pro.

Start free trial

14-day free trial. Cancel anytime.

Sub-surface · on the nymphunder the surface

Hatch predictions

See the full sub-surface read with Pro.

Start free trial

14-day free trial. Cancel anytime.

Beyond the hatch · worth watchingambient prey

Hatch predictions

See what else is on the menu with Pro.

Start free trial

14-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 · August highlighted

Trout season

Grannom

Evening Sedge

Large Dark Olive

Iron Blue

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

Water here around 23°C. Nothing cooler within range — carry a thermometer.

About this water

Limestone

Water quality (WFD)

Ecology: Good
Chemical: Unknown

What this classification means

WFD classification · ES091MSPF698

The full read · show the working · for Brown Trout · confidence 90%

How the 0 is built — score × weight = contribution

Temperature2 × 28%0.6

Flow80 × 22%17.6

Clarity15 × 18%2.7

Feeding Time60 × 13%7.8

Pressure80 × 7%5.6

Insect activity41 × 12%4.9

Limiting factor: Water temperature (22.8°C) is outside Brown Trout's preferred range (10–16°C)= 39

Can you trust it?

Water temperatureair-to-water estimateestimated

Level / flowproxy via Río Iratiproxy

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.

The dawn and dusk windows score higher than the midday lull.

Directions

Apple Maps Google 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.

Booking & contacts