- Ecology: Moderate
- Chemical: Unknown
WFD classification · ES091MSPF546
Water temperature for Brown Trout
Warm — slow24°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 23.6°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 3 active hatches hour by hour with Pro.
Start free trial14-day free trial. Cancel anytime.
Beyond the hatch · worth watchingambient prey
Hatch predictions
See what else is on the menu with Pro.
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 · 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
- Use the exact tramo and daily-permit structure for the section you plan to fish rather than assuming one simple Arga rule.
What's coming
Plan ahead
5-day outlook
Water here around 24°C. Nothing cooler within range — carry a thermometer.
Gallery · 2
Puente la Reina Terrain map
Water quality (WFD)
The full read · show the working · for Brown Trout · confidence 90%
How the 0 is built — score × weight = contribution
Temperature0 × 28%0.0
Flow80 × 22%17.6
Clarity15 × 18%2.7
Feeding Time60 × 13%7.8
Pressure80 × 7%5.6
Insect activity30 × 12%3.6
Limiting factor: Water temperature (23.6°C) is outside Brown Trout's preferred range (10–16°C)= 37
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.
The dawn and dusk windows score higher than the midday lull.
Directions
Seasons & zones
- Trout 1 May → 30 June
RSS Arga–Ultzama basin (922 permits in 2026). All catch-and-release. Extendable to 15 Jul by resolution. Daily basin permit required. Tramo-specific rules apply — check the official web app for stretch-level status.
Related guides
Booking & contacts
Río Arga
Water temperature for Brown Trout
Warm — slow24°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 23.6°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 3 active hatches hour by hour with Pro.
Start free trial14-day free trial. Cancel anytime.
Beyond the hatch · worth watchingambient prey
Hatch predictions
See what else is on the menu with Pro.
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 · 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
- Use the exact tramo and daily-permit structure for the section you plan to fish rather than assuming one simple Arga rule.
What's coming
Plan ahead
5-day outlook
Water here around 24°C. Nothing cooler within range — carry a thermometer.
Gallery · 2
Puente la Reina Terrain map
Water quality (WFD)
- Ecology: Moderate
- Chemical: Unknown
WFD classification · ES091MSPF546
The full read · show the working · for Brown Trout · confidence 90%
How the 0 is built — score × weight = contribution
Temperature0 × 28%0.0
Flow80 × 22%17.6
Clarity15 × 18%2.7
Feeding Time60 × 13%7.8
Pressure80 × 7%5.6
Insect activity30 × 12%3.6
Limiting factor: Water temperature (23.6°C) is outside Brown Trout's preferred range (10–16°C)= 37
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.
The dawn and dusk windows score higher than the midday lull.
Directions
Seasons & zones
- Trout 1 May → 30 June
RSS Arga–Ultzama basin (922 permits in 2026). All catch-and-release. Extendable to 15 Jul by resolution. Daily basin permit required. Tramo-specific rules apply — check the official web app for stretch-level status.
Related guides
Booking & contacts