Lowland · Mixed · East / Meath, IE

Mongagh & Yellow Rivers

Mongagh & Yellow Rivers terrain map

Two small Boyne tributaries near Castlejordan — the Mongagh coming down from near Tyrrellspass, the Yellow from north of Daingean.

Marginal · Brown Trout
Pheasant Tail Nymph · 14-18
Slow going — pick your moments
River lifting fast on the rain. Slow going — pick your moments and do not force it.
45% confidence
limited data
What moved it
  • LevelProxyvia Boyne
  • Water temp14.6°C
  • ClarityVery colouredColouring up
Today's fly
Pheasant Tail Nymph
Pheasant Tail Nymph14-18
Upstream
Conditions on the water
Proxy gauge
Level
Rising
Proxy
via Boyne
Water temp14.6°C
ClarityVery coloured
Weather14°C
WindW 25 km/h
Pressure1009 hPa
Rain · recent2.9 mm
Rain · ahead0.0 mm

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

Water temperature for Brown Trout
Ideal
15°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
Poor — water temperature is working for you, but water clarity is the limiting factor today.
Likely species
Mayflies
Caddisflies
Gammarids
Hatch timeline · todayPeak at 11am

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

Supporters see the full sub-surface read.

Start free trial

14-day free trial. Cancel anytime.

Beyond the hatch · worth watchingambient prey(1)

Hatch predictions

Top prey shown — see all 5 as a supporter.

Start free trial

14-day free trial. Cancel anytime.

Evidence
Survey-backed · regionalHigh confidence

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

Through the year
0–3 scale · September highlighted
J
F
M
A
M
J
J
A
S
O
N
D
Trout seasonSeason
1
2
2
2
2
2
1
Mayfly (Green Drake)Hatch
2
2
Large Cinnamon SedgeHatch
2
3
3
2
Daddy Long LegsHatch
2
3
2
CapererHatch
2
3
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
Fishing better nearby · 5
Riverstown River
15 km
85
Brown trout
River Deel (Meath)
15 km
Brown trout
Enfield Blackwater
17 km
Brown trout
Stoneyford River
19 km
Brown trout
Lough Ennell
23 km
Brown trout · Pike
About this water

Two small Boyne tributaries near Castlejordan — the Mongagh coming down from near Tyrrellspass, the Yellow from north of Daingean. Both hold good stocks of small wild brown trout, with better fish to two pounds in the lower reaches below Clongall Bridge. Edenderry & Castlejordan Angling Association controls the fishing and runs it catch-and-release, with sanctuary areas in operation — so it pays to check which stretches are open before you set off.

Hatches & food

Two small mixed-geology Boyne tributaries with typical small-stream fly life — spring olives, summer Blue-Winged Olive and sedge, and a heavy reliance on black gnat and other terrestrials on the lower, slower reaches.

  • Mixed
The full read · show the working · for Brown Trout · confidence 45%
How the 30 is built — score × weight = contribution
Temperature100 × 28%28.0
Flow55 × 22%12.1
Clarity15 × 18%2.7
Feeding Time70 × 13%9.1
Pressure80 × 7%5.6
Insect activity57 × 12%6.8
Limiting factor: Water is very coloured — too coloured for Brown Trout= 64
Can you trust it?
Water temperatureair-to-water estimateestimated
Level / flowproxy via Boyneproxy
Prey activitysurvey-backed invertebrate datasurvey
What would change the calculation
A drop and clear would lift the flow and clarity scores.
Directions
Apple MapsGoogle Maps
Seasons & zones
  • Trout 1 March → 30 September
Related guides
ConnemaraIrish fishingEuro Nymphingsubsurface methods
Casting instructors near here
Booking & contacts
Permits & access