Spate · Mixed · Asturias, Spain

Río Riosa

Río Riosa — Casa en Riosa

Small enough that you can step across it in places, which shouldn't encourage false confidence.

Marginal · Brown Trout
Ignita CDC · 16-20
Marginallive now
Slow going — pick your moments
River temperature is the limiting factor today, not the flow. Fish dawn or dusk if you go at all, and handle everything with extra care.
90% confidence
What moved it
  • Level0.36 mLast reading 2h ago
  • Water temp18.3°C
  • ClarityClear
Today's fly
IC
Ignita CDC16-20
Upstream dry, on top
Conditions on the water
Live gauge
Level
Steady
0.36 m
Last reading 2h ago
Water temp18.3°C
ClarityClear
Weather18°C
WindN 7 km/h
Pressure1020 hPa
Rain · recent0.0 mm
Rain · ahead4.9 mm

The nearest gauge doesn't record temperatures, so we've estimated it — defer to the river keeper's advice.

Water temperature for Brown Trout
Warm — slow
18°C est.ideal 1016°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 18.3°C — above the brown trout caution line (18°C). Fish dawn or dusk only. Land it fast, wet hands, no air shots.
Hatch timeline · todayPeak at 6pm

Hatch predictions

Today's headline hatch shown — see all 12 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 3 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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Through the year
0–3 scale · August highlighted
J
F
M
A
M
J
J
A
S
O
N
D
Trout seasonSeason
1
2
2
1
March BrownHatch
2
3
2
GrannomHatch
2
2
Large StoneflyHatch
2
3
2
Yellow SallyHatch
2
3
2

Numbers are intensity 0 (none) to 3 (peak) — a guide, not a guarantee.

Ranked for today
Brown Trout fly box
Beats · 1
Riosa · 0.5 kmC&R trout
C&R trout stretch — Puente Bº La Ará Cta A-231 General to Puente pasarela aguas abajo del polideportivo.
Beat detail
Daily permit required, all fish returned
Upstream: Puente Bº La Ará Cta A-231 General
Downstream: Puente pasarela aguas abajo del polideportivo
Riosa beat map
Permits & access
Free state water
State rod licence required for trout / salmon as applicable.
  • Asturian fishing licence required.
What's coming
Plan ahead
5-day outlook
Water here around 18°C. Nothing cooler within range — carry a thermometer.
Gallery · 2
  1. Río Riosa — Casa en Riosa
    Casa en Riosa
  2. Terrain map of the venue
    Terrain map
About this water

Small enough that you can step across it in places, which shouldn't encourage false confidence. The Riosa holds wild browns in runs no wider than a doorway, under alders that make the casting interesting. The fish are modest in size and precise in their requirements, and they will let you know immediately if you've been sloppy.

Under the surface

The Riosa arrives into the Nalón system bringing steep Cantabrian descent and mixed lithology character. The upper reaches are step-pool slate and quartzite; the descent is steep and response to rainfall pronounced. The middle Riosa allows pool-riffle sequences to develop on cobble; these pools are known and respected. The river maintains its responsive character — quick to rise, quick to fall, connected fully to mountain weather — throughout.

Wading: Wet boulder tops and lichen glazed bedrock steps

Hatches & food

In the mountain-to-sea trout rivers of Asturias, olives and other mayflies do much of the work in spring whenever levels and colour allow, followed by strong evening caddis and steady buzzer life through early and mid-summer, with terrestrials and mixed surface food from wooded, pastoral banks rounding out the diet whenever flows drop back into safe wading range.

  • Mixed
  • Confined
  • Step pool
  • Pocket water
The full read · show the working · for Brown Trout · confidence 90%
How the 38 is built — score × weight = contribution
Temperature51 × 28%14.3
Flow80 × 22%17.6
Clarity95 × 18%17.1
Feeding Time85 × 13%11.1
Pressure80 × 7%5.6
Insect activity60 × 12%7.2
Conditions total= 73
Can you trust it?
Water temperatureair-to-water estimateestimated
Level / flowon-river gaugeobserved
What would change the calculation
Cooler water — back toward the 10–16 °C ideal band — would lift the score and ease welfare.
Directions
Seasons & zones
  • Trout Third Sunday of May15 August

    The Riosa joins the Nalón above Puente Peñaflor (Grado) — the Nalón's salmon-zone limit — so it sits in the mountain-zone tributary network rather than the general lowland default. Mountain-zone trout (zona de alta montaña): opens Third Sunday of May, not the general 15 March, minimum size 17cm (vs. 19cm general). Asturian regulation classifies any tributary joining above a salmon river's designated zone-limit point as alta montaña water. Inferred here from confluence position, not a verified lookup against the official cotos map (pescafluvial.asturias.es) — confirm before treating as final.

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