Spate · Peat · Outer Hebrides / Lewis

Grimersta River & Loch System

Grimersta River & Loch System terrain map
Terrain map

Scotland's most famous island salmon fishery — a short, fast spate river draining a chain of lochs on the west side of Lewis.

Good · Atlantic Salmon
Goodlive now
A good day — worth the effort
River high but settled. Water still carrying colour. Heavier flies, settled lies.
50% confidence
What moved it
  • LevelProxyvia River Ewe / Loch Maree
  • Water temp11.9°C
  • ClaritySlightly coloured
Conditions on the water
Proxy gauge
Level
Steady
Proxy
via River Ewe / Loch Maree
Water temp11.9°C
ClaritySlightly coloured
Weather12°C
WindN 11 km/h
Pressure1022 hPa
Rain · recent8.3 mm
Rain · ahead14.6 mm

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

Water temperature for atlantic salmon
Ideal
12°C est.ideal 10–14°C
0°14°28°
How to fish it · for atlantic salmon
When
All day — lough fishing is best in a good wave. Early morning and evening can produce in calm conditions.
Where
Work the drift lanes from the upwind shore across the productive zones. Cover bay edges, underwater reefs, and any areas where the bottom shoals.
Method
Fish a sensible line-and-fly combination for the height and pace of water.
Kit
10 ft #7/8 single-hander, floating line, 10–12 lb fluoro leader. Boat seat and waterproofs for the drift.
Why this works
Good — water temperature is working for you, but time of day is the limiting factor today.
Hatch timeline · todayQuiet day

Hatch predictions

Today's headline hatch shown — see all 2 active hatches hour by hour with Pro.

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Evidence
Survey-backed · regionalModerate confidence

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

Through the year
0–3 scale · July highlighted
J
F
M
A
M
J
J
A
S
O
N
D
Salmon runRun
1
2
2
2
2
2
2
2
1
Daddy Long LegsHatch
2
3
2
Murrough (Great Red Sedge)Hatch
2
3
2
Black MidgeHatch
2
3
3
3
3
3
3
3
3
3
3
2
Lake OliveHatch
1
2
2
2
2
2
1

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

Permits & access
Permit required — see local rules.
  • Premium managed fishery — advance booking through Grimersta Estate
  • Very limited availability
  • Fly only.
What's coming
Plan ahead
5-day outlook
Other water nearby · 3
Loch Roag System
5.0 km
Brown trout · Salmon · Sea trout
Loch Morsgail
9.0 km
Brown trout · Salmon · Sea trout
Loch Langavat (Lewis)
15 km
Brown trout · Char · Salmon
About this water

Scotland's most famous island salmon fishery — a short, fast spate river draining a chain of lochs on the west side of Lewis. The Grimersta is extraordinary: in a good spate it can produce salmon catches that rival any river in Scotland, despite being barely a mile long. The system's magic lies in its chain of lochs which act as holding pools, and the short river which fish run through in hours rather than days after rain. Sea trout also run the system in good numbers. The fishing is managed as a premium let and commands high prices, but when it fires after a summer spate, there is nothing else quite like it in Scottish salmon fishing. Peat-stained moorland water defines this river. Atlantic salmon stocks are Category 3 (declining) — all salmon must be released.

  • Loch
  • Peat
Why this score · for atlantic salmon
  • Temperature10030% weight
  • Flow6025% weight
  • Clarity8520% weight
  • Feeding Time1015% weight
  • Pressure8510% weight
Directions
Apple MapsGoogle Maps
Seasons & zones
  • Salmon11 February → 31 October

Sea trout: Variable seasonal (2026) — Grimersta — the most celebrated sea trout system in the British Isles historically. Lewis loch chain with a legendary record for very large sea trout. Stocks have collapsed under sea-lice pressure from west-coast salmon farms; catches are a fraction of their 1970s–80s peak. Still worth fishing carefully when conditions align, but the days of double-figure fish in numbers are gone. Catch-and-release mandatory under contemporary estate management.

Related guides
Scotland Playbookloch & river fishingThermal Layers & Troutreading depth and temperatureAtlantic Salmonsalmon tactics
Booking & contacts