Spate · Mixed · East / Louth

Ballymascanlan River

The Ballymascanlan River flowing through wooded grounds in County Louth, Ireland

The Ballymascanlan rises on Slieve Gullion and runs some fourteen miles to Dundalk Bay.

Marginal · Brown Trout
Pheasant Tail Nymph · 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.
90% confidence
What moved it
  • LevelProxyvia River Glyde
  • Water temp18.2°C
  • ClarityClear
Today's fly
Pheasant Tail Nymph
Pheasant Tail Nymph14-18
Upstream
Conditions on the water
Proxy gauge
Level
Steady
Proxy
via River Glyde
Water temp18.2°C
ClarityClear
Weather24°C
WindSW 16 km/h
Pressure1020 hPa
Rain · recent0.0 mm
Rain · ahead1.2 mm

No gauge on this water — conditions are inferred from River Glyde. The trend transfers, the absolute level does not.

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 18.2°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 6am

Hatch predictions

Today's headline hatch shown — see all 9 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 2 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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Evidence
Survey-backed · regionalHigh confidence

Backed by regional invertebrate surveys; no sampling on this exact reach yet.

Updated 23 hours ago

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
2
2
2
1
Daddy Long LegsHatch
2
3
2
March BrownHatch
2
3
2
GrannomHatch
2
2
Large StoneflyHatch
2
3
2

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

Ranked for today
Brown Trout fly box
What's coming
Plan ahead
5-day outlook
Cooler water nearby · 1
Water here around 18°C — probably warm enough to stress Brown Trout . These are likely cooler.
Gallery · 2
  1. The Ballymascanlan River flowing through wooded grounds in County Louth, Ireland
    The River Ballymascanlon in the grounds of Ballymascanlon House, County Louth
  2. Terrain map of the venue
    Terrain map
About this water

The Ballymascanlan rises on Slieve Gullion and runs some fourteen miles to Dundalk Bay. It holds a modest stock of brown trout, but its summer salmon and sea trout are the draw, and the best of that lies in the pools below Ballymascanlan Bridge. This is a spate river: fish it after a flood, when fresh fish have run up on the rising water. Work the pools at night from July to September. Dundalk Brown Trout Anglers hold the day permits.

Hatches & food

A flashy Slieve Gullion spate stream where stoneflies and terrestrials outweigh upwings; hatches are sparse and flood-driven, with night sedges the key food once sea trout run in summer.

  • Mixed
The full read · show the working · for Brown Trout · confidence 90%
How the 39 is built — score × weight = contribution
Temperature53 × 28%14.8
Flow80 × 22%17.6
Clarity95 × 18%17.1
Feeding Time55 × 13%7.2
Pressure80 × 7%5.6
Insect activity62 × 12%7.4
Conditions total= 70
Can you trust it?
Water temperatureair-to-water estimateestimated
Level / flowproxy via River Glydeproxy
Prey activitysurvey-backed invertebrate datasurvey
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
Seasons & zones
  • Trout 1 March30 September

Sea trout: Variable seasonal (2026)

Related guides
Casting instructors near here
Booking & contacts
Permits & access