Spate · Mixed · Primorsko-goranska / Gorski Kotar

Kupica

Rijeka Kupica venue image
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Fast Kupa tributary in Gorski Kotar — cold, well-oxygenated spate water with wild brown trout and grayling.

Poor · Brown Trout
Large Dry Fly · 12-16
Poorlive now
Not the day for it
River high but settled. Take your time — read the water before you cast.
90% confidence
What moved it
  • LevelProxyvia River Kolpa
  • Water temp23.0°C
  • ClarityColouredClearing
Today’s fly
LD
Large Dry Fly12-16
Proven pattern for this period
Conditions on the water
Proxy gauge
Level
Falling
Proxy
via River Kolpa
Water temp23.0°C
ClarityColoured
Weather24°C
WindN 5 km/h
Pressure1018 hPa
Rain · recent21.2 mm
Rain · ahead0.9 mm

No gauge on this water — conditions are inferred from River Kolpa. 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 23°C. This is the line where catch-and-release kills brown trout. Do not fish for them today.
Hatch timeline · todayQuiet day

Hatch predictions

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

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Evidence
ModelledModerate confidence

Modelled from regional ecology — no survey or occurrence data for this water yet.

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
2
2
1
Grayling seasonSeason
1
2
2
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
LD
Large Dry FlyTop
12-16 · Pattern
Proven pattern for this period
Permits & access
Permit required — see local rules.
  • Croatian fishing licence + local permit.
What's coming
Plan ahead
5-day outlook
Water here around 23°C. Nothing cooler within range — carry a thermometer.
Gallery · 1
  1. Terrain map of the venue
    Terrain map
About this water

Fast Kupa tributary in Gorski Kotar — cold, well-oxygenated spate water with wild brown trout and grayling. Steep gradient with pocket water and short pools. Responsive to rain. Tight-line nymphing the dominant method on faster stretches. Part of the Gorski Kotar grayling river network.

  • Mixed
Water quality (WFD)
  • Ecology: Good
  • Chemical: Unknown

WFD classification · HRCSRN0130_001

The full read · show the working · for brown trout · confidence 90%
How the 4 is built — score × weight = contribution
Temperature2 × 28%0.6
Flow80 × 22%17.6
Clarity40 × 18%7.2
Feeding Time80 × 13%10.4
Pressure80 × 7%5.6
Insect activity43 × 12%5.2
Limiting factor: Water temperature (23°C) is outside Brown Trout's preferred range (10–16°C)= 47
Can you trust it?
Water temperatureair-to-water estimateestimated
Level / flowproxy via River Kolpaproxy
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.
Directions
Apple MapsGoogle Maps
Seasons & zones
  • Trout1 March → 30 September
  • Grayling16 May → 15 October
Related guides
Grayling Playbookgrayling tacticsEuro Nymphingsubsurface methods
Booking & contacts