Spate · Mixed Sedimentary · West Coast

Grey River / Māwheranui

The Grey is the great river of its West Coast valley — a big spate river holding strong brown trout in its runs and clearer tributaries.

Species

A proper day on the water

Low and clear — careful approach country. Stay small, stay accurate.

The water's still cold, about 10°C, running clear, sitting at a steady height.

90% confidence in this read
Water temperature for brown trout
Cool — slow
10°C est.ideal 1016°C
0°14°28°
The full read · show the working · for brown trout · confidence 90%
How the 78 is built — score × weight = contribution
Temperature93 × 28%26.0
Flow60 × 22%13.2
Clarity95 × 18%17.1
Feeding Time70 × 13%9.1
Pressure80 × 7%5.6
Insect activity54 × 12%6.5
Conditions total= 78
Can you trust it?
Water temperatureair-to-water estimateestimated
Level / flowon-river gaugeobserved
Conditions
Regional est.
Level
Moderate rain recently
No gauge reading
Water temp
9.6°C
Estimated
Clarity
Clear
Air temp
7°C
Wind
E 8 km/h
Light breeze
Pressure
1012 hPa
Rain · 48h
21.7 mm
Moderate rain
Rain · ahead
2.2 mm
Light rain · next 48h

No gauge on this water — readings are regional estimates from weather, not a live gauge.

Weather-only: no live gauge wired. Spate river — fishability is driven by falling/clearing flow after rain. Stale data is dangerous; conditions change fast.

Hatch timeline · todayQuiet day

Hatch predictions

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

Start free trial

14-day free trial. Cancel anytime.

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
Good — water clarity is right today, though insect activity could be better.
Through the year
0–3 scale · June highlighted
J
F
M
A
M
J
J
A
S
O
N
D
Trout seasonSeason
2
2
2
1
1
2
2
Deleatidium / NZ Mayfly DunHatch
3
3
3
3
2
2
3
3
3
Large Dark MayflyHatch
3
3
2
2
3
Burrowing Mayfly / Green MayflyHatch
3
2
2
Caddis / SedgeHatch
3
3
3
2
2
3

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

Permits & access
Permit required — see local rules.
  • West Coast Fish & Game — a Fish & Game licence is required
  • Check the current Anglers Notice
  • Check Clean Dry (didymo present).
Directions
About this water

The Grey is the great river of its West Coast valley — a big spate river holding strong brown trout in its runs and clearer tributaries. Like all West Coast water it lives by the weather: after rain it runs high and coloured, and as it falls and clears toward normal it switches on. The tributaries clear first and offer the early option.

Under the surface

The Grey — Māwheranui — gathers the rain of the Southern Alps and the Paparoa Range and runs broad and powerful through the Grey valley to the sea at Greymouth, a big West Coast river of long runs and bush-lined reaches. Strong brown trout hold its runs and the clearer tributaries, in high-rainfall country where the river rises and falls fast.

Wading: Big spate river, fast rises after rain, slick gravel — read the level

  • River
  • Mixed sedimentary
  • Partly confined
  • Large river
  • Pool riffle
Seasons & zones
  • Trout1 October (main river); some back-country 1 November → 30 April (back-country) / year-round (lower)
Related guides