Tailwater · Mixed · Montana

Red Rock River

Red Rock River terrain map

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.

Prime · Brown Trout
Sparkle Dun · 14-18
Primelive now
About as good as it gets
River steady at a fishable height. On the feed top to bottom — start on the rises with a dry, drop a nymph if they stay down.
90% confidence
What moved it
  • Level0.88 mLast reading 14h ago
  • Water temp10.3°C
  • ClarityClear
Today's fly
SD
Sparkle Dun14-18
High-confidence seasonal pick
Conditions on the water
Live gauge
Level
Steady
0.88 m
Last reading 14h ago
Water temp10.3°C
ClarityClear
Weather13°C
WindSE 2 km/h
Pressure1019 hPa
Rain · recent0.0 mm
Rain · ahead0.1 mm

Live readings — water temperature is an estimate where the gauge does not record it.

Water temperature for Brown Trout
Ideal
10°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
Excellent — water temperature is right today, though insect activity could be better.
Hatch timeline · todayQuiet day

Hatch predictions

Today's headline hatch shown — see all 3 active hatches hour by hour with Pro.

Start free trial

14-day free trial. Cancel anytime.

Sub-surface · on the nymphunder the surface

Hatch predictions

Top nymph shown — see all 3 guilds with Pro.

Start free trial

14-day free trial. Cancel anytime.

Beyond the hatch · worth watchingambient prey

Hatch predictions

See what else is on the menu with Pro.

Start free trial

14-day free trial. Cancel anytime.

Evidence
ModelledModerate confidence

Modelled from regional ecology — no survey or occurrence data for this water yet.

Through the year
0–3 scale · July 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
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
Temperature100 × 28%28.0
Flow80 × 22%17.6
Clarity95 × 18%17.1
Feeding Time60 × 13%7.8
Pressure80 × 7%5.6
Insect activity60 × 12%7.2
Conditions total= 83
Can you trust it?
Water temperatureair-to-water estimateestimated
Level / flowon-river gaugeobserved
Prey activitymodelled from regional profilemodelled
What would change the calculation
The dawn and dusk windows score higher than the midday lull.
Directions
Apple MapsGoogle Maps
Seasons & zones
  • TroutThird Saturday of May → Last day of February
Related guides
Euro Nymphingsubsurface methods
Booking & contacts