Chalk Stream · Limestone · Bela Krajina / Semič, SI

Krupa

Krupa — Krupa river in winter

One of the shortest rivers in Slovenia — a karst spring near Semič in Bela Krajina, flowing barely a couple of kilometres before it's spent.

Poor · Brown Trout
Streamer / Woolly Bugger · 6–10
Closed season
Out of season. Try elsewhere.
Closed — confidence not applicable today.
What moved it
  • LevelProxyvia Lahinja at Gradac I
  • Water temp10.3°C
  • ClarityClear
Today's fly
SW
Streamer / Woolly Bugger6–10
High-confidence seasonal pick
Conditions on the water
Proxy gauge
Level
Steady
Proxy
via Lahinja at Gradac I
Water temp10.3°C
ClarityClear
Weather12°C
WindNE 14 km/h
Pressure1027 hPa
Rain · recent0.1 mm
Rain · ahead2.2 mm

No gauge on this water — conditions are inferred from Lahinja at Gradac I. The trend transfers, the absolute level does not.

Water temperature for Brown Trout
Ideal
10°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.
Likely species
Mayflies
Stoneflies
Caddisflies
Aquatic beetles
  • Diving beetlesMost likelyLower confidence
    #8–10–12 · Adult
    Twitch a beetle pattern along weedy edges at dusk.
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 12 active hatches hour by hour as a supporter.

Start free trial

14-day free trial. Cancel anytime.

Sub-surface · on the nymphunder the surface

Hatch predictions

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

Start free trial

14-day free trial. Cancel anytime.

Beyond the hatch · worth watchingambient prey(1)

Hatch predictions

Top prey shown — see all 2 as a supporter.

Start free trial

14-day free trial. Cancel anytime.

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
Brown SedgeHatch
2
3
3
3
2
Small SpurwingHatch
2
3
3
3
2
Freshwater ShrimpHatch
2
3
3
3
3
3
3
3
3
3
3
2
Small Dark OliveHatch
2
3
3
3
2

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

Ranked for today
Brown 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.
  • Bela Krajina ribiška družina (likely RD Črnomelj) — not independently confirmed.
What's coming
Plan ahead
5-day outlook
Other water nearby · 5
River Kolpa
26 km
0
Brown trout · Grayling · Hucho
Krka
35 km
0
Brown trout · Grayling
Kupica
37 km
0
Brown trout · Grayling
Vitunjčica
38 km
0
Brown trout
Dobra
39 km
0
Brown trout · Grayling
Gallery · 2
  1. Krupa — Krupa river in winter
    Krupa river in winter
  2. Terrain map of the venue
    Terrain map
About this water

Marked medium confidence deliberately: it holds trout, but the detail on stocking, permit terms and exact species mix wasn't pinned down with the same certainty as the rest of this pack, so treat it as a lead worth checking locally rather than a settled record.

  • River
  • Limestone
The full read · show the working · for Brown Trout · confidence 90%
How the 0 is built — score × weight = contribution
Temperature100 × 28%28.0
Flow80 × 22%17.6
Clarity95 × 18%17.1
Feeding Time55 × 13%7.2
Pressure80 × 7%5.6
Insect activity64 × 12%7.7
Conditions total= 83
Can you trust it?
Water temperatureair-to-water estimateestimated
Level / flowproxy via Lahinja at Gradac Iproxy
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
Related guides
Chalkstream Playbooklimestone spring creek — same tacticsAlpine Streamsmountain entomologyMarble TroutSoča system
Booking & contacts
At a glance

Krupa is a chalk stream in Bela Krajina / Semič, Slovenia. The catchment geology is recorded as limestone, and the water sits at about 165 m above sea level. The river is described as roughly 2 km long. The species listed for this water is brown trout. The trout season is recorded as running from 1 March to 30 September. Best window recorded for anglers: April–October. Core methods listed: Dry fly; Sight-fishing nymph. Level and flow data for this water is linked from 1 gauge. Nearby waters in our listings include River Kolpa at 26 km, Krka at 35 km and Kupica at 37 km.