Tailwater · Mixed · Montana, US

Red Rock River

RedRockRiverMontana

The Red Rock runs out of the Centennial Valley away up in the southwest corner of Montana, about as far from anything as you can get and still be on a road.

Today · A proper day on the water
Czech Nymph
Forecast · Today
A proper day on the water
A proper day for it. Work the seams with an upstream nymph, switch to the dry when they show.
75% projected
Today's fly
Czech Nymph
Czech Nymph
Conditions on the water · Today
Live gauge
Level
Falling
0.38 m
Dropping after lift
Water temp9.6°C
ClarityClearing
Weather4°C
WindN 12 km/h
Pressure1028 hPa
Rain · recent0.0 mm
Rain · ahead0.0 mm

The nearest gauge doesn't record temperatures, so we've estimated it — defer to the river keeper's advice.

Water temperature for Brown Trout
Cool — slow
10°C est.ideal 10–16°C
0°14°28°

We have not characterised this dam's release, so this is a general cold-release figure and could be several degrees out in either direction. Treat it as a hint, not a reading, and check locally before you fish.

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
Excellent — conditions well-balanced, with water clarity particularly in your favour.
Likely species
Mayflies
Chironomids
Gammarids
Hatch timeline · todayPeak at 11am

12pm(now) — Western Blue-Winged Olive

Stage: On emergersApproach: Emerger or dryActivity: 81%
Also:Black Midge67%
Peak emergence window4 food groups active

Peak activity at 11am — Western Blue-Winged Olive (Western Blue-Winged Olive, Peak emergence window)

Sub-surface · on the nymphunder the surface

Hatch predictions

Supporters see the full sub-surface read.

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Beyond the hatch · worth watchingambient prey(1)

Hatch predictions

Top prey shown — see all 3 as a supporter.

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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
2
1
1
2
2
2
2
2
2
2
Western Blue-Winged OliveHatch
2
3
3
3
3
3
3
3
2
Pale Morning DunHatch
2
3
3
2
TricoHatch
2
3
2
Black MidgeHatch
2
3
3
3
3
3
3
3
3
3
3
2

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

Ranked for today
Brown Trout fly box
Permits & access
Permit required — see local rules.
  • Montana licence
  • Remote, lightly fished, irrigation-controlled
  • Arctic grayling restoration basin — release any grayling unharmed.
What's coming
Plan ahead
5-day outlook
Other water nearby · 1
Clark Canyon Reservoir
57 km
Brown trout · Rainbow trout
Gallery · 2
  1. RedRockRiverMontana
  2. Terrain map of the venue
    Terrain map
About this water

The Red Rock runs out of the Centennial Valley away up in the southwest corner of Montana, about as far from anything as you can get and still be on a road. Below Lima Reservoir it's a small, brushy tailwater holding browns and rainbows, and the wider basin is some of the most important Arctic grayling restoration country in the lower 48 — handle any grayling you meet like the rarity it is. It's remote, lightly fished, and irrigation-controlled, so the flow you get depends on what the dam's doing for the hayfields downstream.

  • Mixed
Water quality · US Clean Water Act
  • Aquatic life: Impaired
  • Recreation: Impaired
What this classification means

Recreation: Bacteria/pathogen advisory — mind wading cuts and immersion.

EPA ATTAINS assessment unit 'Red Rock River' (MT41A001_020), 2021 Integrated Report. Aquatic Life use: Not Supporting. Listed impairment causes: Temperature, Sediment, Nutrients, Habitat Alterations, Pathogens. This is a Clean Water Act assessment-unit classification (the US analogue of WFD), not a live reading.

Status is for the Clean Water Act assessment unit covering this reach.

EPA ATTAINS (Clean Water Act) · MT41A001_020

The full read · show the working · for Brown Trout · confidence 90%
How the 83 is built — score × weight = contribution
Temperature93 × 28%26.0
Flow80 × 22%17.6
Clarity95 × 18%17.1
Feeding Time70 × 13%9.1
Pressure80 × 7%5.6
Insect activity66 × 12%7.9
Conditions total= 83
Can you trust it?
Water temperatureair-to-water estimateestimated
Level / flowon-river gaugeobserved
Prey activitymodelled from regional profilemodelled
Directions
Apple MapsGoogle Maps
Seasons & zones
  • Trout Third Saturday of May → Last day of February
Related guides
Euro Nymphingsubsurface methods
Booking & contacts