Freestone · Granite · Castilla y León

Río Eresma

Río Eresma terrain map
Terrain map

The Eresma rises in the Sierra de Guadarrama at Valsaín — the upper river through La Granja and into Segovia city is genuine wild-trout water, with strong granite-headwater character and excellent clarity.

Marginal · Brown Trout
Klinkhammer · 14-18
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.
80% confidence
What moved it
  • Level0.51 mLast reading 5h ago
  • Water temp18.9°C
  • ClarityClear
Today’s fly
Klinkhammer
Klinkhammer14-18
High-confidence seasonal pick
Conditions on the water
Live gauge
Level
Steady
0.51 m
Last reading 5h ago
Water temp18.9°C
ClarityClear
Weather20°C
WindS 11 km/h
Pressure1019 hPa
Rain · recent0.0 mm
Rain · ahead0.0 mm

Live readings — water temperature is an estimate where the gauge does not record it.

Water temperature for brown trout
Warm — slow
19°C est.ideal 10–16°C
0°14°28°
How to fish it · for brown trout
When
Through the Castilla y León trout season — 3rd Sunday of March to 31 July. Spring olives April through May; summer sedges in evening hours; sin muerte stretches extend through autumn.
Where
Pool tails, riffle heads, and the seams behind boulders through the Segovian beats. The Eresma runs from the Sierra de Guadarrama through clear granite pocket water.
Method
Upstream dry to risers; dry-dropper through the riffles. The water reads clear — long leader, fine tippet, careful approach.
Kit
9 ft #4 — Castilian default. Floating line, 12 ft leader to 4 lb fluoro. Studded boots — granite cobble runs slick.
Why this works
⚠️ Water at 18.9°C — above the brown trout caution line (18°C). Fish dawn or dusk only. Land it fast, wet hands, no air shots. Otherwise poor — water clarity is in the right range.
Hatch timeline · todayPeak at 5pm

Hatch predictions

Today's headline hatch shown — see all 3 active hatches hour by hour with Pro.

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Sub-surface · on the nymphunder the surface

Hatch predictions

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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
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
2
2
2
1
Large Dark OliveHatch
1
2
2
1
Blue Winged OliveHatch
1
2
2
2
2
1
Autumn OliveHatch
1
2
1
GrannomHatch
1
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.
  • Se requiere licencia de Castilla y León
  • El tramo Valsaín–La Granja es la identidad de trucha salvaje del río; los tramos bajos urbanos y agrícolas siguen una gestión distinta (a menudo de repoblación)
  • Ajusta el tramo a tu objetivo antes de reservar.
What's coming
Plan ahead
5-day outlook
Cooler water nearby · 1
Water here around 19°C — probably warm enough to stress brown trout. These are likely cooler.
Río Moros
23 km
~18°C
Brown trout
About this water

The Eresma rises in the Sierra de Guadarrama at Valsaín — the upper river through La Granja and into Segovia city is genuine wild-trout water, with strong granite-headwater character and excellent clarity. Lower reaches downstream of Segovia city become more mixed: stocked beats, urban influence, and warmer summer flow mean the Eresma's fly-fishing identity sits firmly in the upper basin around Valsaín / La Granja, not in the broader river.

  • Granite
The full read · show the working · for brown trout · confidence 80%
How the 34 is built — score × weight = contribution
Temperature41 × 28%11.5
Flow80 × 22%17.6
Clarity95 × 18%17.1
Feeding Time50 × 13%6.5
Pressure80 × 7%5.6
Insect activity65 × 12%7.8
Conditions total= 66
Can you trust it?
Water temperatureair-to-water estimateestimated
Level / flowon-river gaugeobserved
Prey activitymodelled from regional profilemodelled
What would change the calculation
Cooler water — back toward the 10–16 °C ideal band — would lift the score and ease welfare.
The dawn and dusk windows score higher than the midday lull.
Directions
Apple MapsGoogle Maps
Seasons & zones
  • TroutLast Sunday of March → 31 July
Related guides
Pyrenees PlaybookSpanish riversEuro Nymphingsubsurface methods
Booking & contacts