Freestone · Limestone · Primorska / Goriška Brda (Italian border), SI

Idrija (Judrio)

Idrija (Judrio) — Fiume Judrio, alto corso

Not to be confused with the Idrijca — this is the Idrija, known on the Italian side of the border as the Judrio, a border river through the Goriška Brda wine country managed by RD Soča.

Good · Rainbow Trout
Streamer / Woolly Bugger · 6–10
Goodlive now
A proper day on the water
River steady at a fishable height. A proper day for it. Work the seams with an upstream nymph, switch to the dry when they show.
75% confidence
What moved it
  • Level0.89 mLast reading 4h ago
  • Water temp12.3°C
  • ClarityClear
Today's fly
SW
Streamer / Woolly Bugger6–10
High-confidence seasonal pick
Conditions on the water
Live gauge
Level
Steady
0.89 m
Last reading 4h ago
Water temp12.3°C
ClarityClear
Weather10°C
WindNE 15 km/h
Pressure1024 hPa
Rain · recent0.0 mm
Rain · ahead0.0 mm

Live readings only. Trends shown where the gauge supports them.

Water temperature for Rainbow Trout
Ideal
12.3°Cideal 10–18°C
0°14°28°
How to fish it · for Rainbow 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
Good — water temperature is right today, though time of day could be better.
Likely species
Mayflies
Stoneflies
Caddisflies
Gammarids
Molluscs
  • Pond snailsMost likelyLower confidence
    #10–12–14 · Adult
    Dead-drift or twitch a snail pattern near weed beds.
Oligochaetes
  • Aquatic wormsMost likelyLower confidence
    #12–14–16 · Adult
    Dead-drift a worm pattern deep - a year-round staple.
Hatch timeline · todayQuiet day

Hatch predictions

Today's headline hatch shown — see all 8 active hatches hour by hour as a supporter.

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Sub-surface · on the nymphunder the surface

Hatch predictions

Top nymph shown — see all 3 guilds as a supporter.

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Beyond the hatch · worth watchingambient prey(1)

Hatch predictions

Supporters see what else is on the menu.

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Evidence
Records-basedModerate confidence

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

Through the year
0–3 scale · October highlighted
J
F
M
A
M
J
J
A
S
O
N
D
Trout seasonSeason
1
2
2
2
2
2
1
Evening SedgeHatch
2
3
3
3
2
Alpine RhithrogenaHatch
1
2
2
1
Large Dark OliveHatch
1
2
2
1
Iron BlueHatch
1
2
2
2
2
2
2
1

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

Ranked for today
Rainbow Trout fly box

Ultra-clear spring-fed rivers with large educated trout. Sight fishing, technical presentation, fine tippets. Euro-nymphing dominant subsurface method. Exceptional dry-fly windows during hatch periods. Gacka is the flagship water.

SW
Streamer / Woolly BuggerTop
6–10 · Pattern
High-confidence seasonal pick
Permits & access
Permit required — see local rules.
  • Fly-only, barbless.
What's coming
Plan ahead
5-day outlook
Other water nearby · 5
Natisone
20 km
Brown trout · Marble trout · Grayling
Nadiža
26 km
67
Marble trout · Marble brown hybrid trout · Grayling
River Bača
29 km
83
Brown trout · Marble trout · Rainbow trout
River Trebuščica
29 km
Brown trout · Marble trout
Tolminka
30 km
70
Marble trout · Marble brown hybrid trout · Brown trout
Gallery · 2
  1. Idrija (Judrio) — Fiume Judrio, alto corso
    Fiume Judrio, alto corso
  2. Terrain map of the venue
    Terrain map
About this water

Genuinely a separate water from its better-known near-namesake, with marble and hybrid trout, brown trout, rainbow, and Italian chub drifting across from the downstream Italian reach. Store it with confluence coordinates, not just the name — this is exactly the kind of naming collision that causes real bugs.

  • River
  • Limestone
The full read · show the working · for Rainbow Trout · confidence 75%
How the 79 is built — score × weight = contribution
Temperature100 × 28%28.0
Flow80 × 22%17.6
Clarity85 × 18%15.3
Feeding Time45 × 13%5.9
Pressure75 × 7%5.3
Insect activity57 × 12%6.8
Conditions total= 79
Can you trust it?
Water temperaturelive gauge readinggauge
Level / flowon-river gaugeobserved
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
  • Trout 1 March → 30 September
  • Marble trout 1 April → 31 October
Related guides
Alpine Streamsmountain entomologyMarble TroutSoča systemEuro Nymphingsubsurface methods
Booking & contacts
Clubs & associations
  • RD Soča
    Permit required
At a glance

Idrija (Judrio) is a freestone river in Primorska / Goriška Brda (Italian border), Slovenia. The catchment geology is recorded as limestone, and the water sits at about 96 m above sea level. The river is described as roughly 18 km long. Our data lists 5 species here, including marble trout, marble brown hybrid trout and brown trout. The trout season is recorded as running from 1 March to 30 September. The marble trout season is recorded as running from 1 April to 31 October. Best window recorded for anglers: April–October. Core methods listed: Dry fly; Upstream nymph. Level and flow data for this water is linked from 1 gauge. Nearby waters in our listings include Natisone at 20 km, Nadiža at 26 km and River Bača at 29 km.