Tailwater · Mixed · Montana

Kootenai River

Kootenai River — 18205 Lake Koocanusa

The Kootenai below Libby Dam is big, cold tailwater — huge volume, steady release-driven flow, and rainbows that grow heavy on the year-round chill.

Prime · Rainbow Trout
Sparkle Dun · 14-18
Primelive now
About as good as it gets
River high but settled. Coloured water — fish bigger and deeper, confident takes down the seams.
90% confidence
What moved it
  • Level6.05 mLast reading 18h 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
6.05 m
Last reading 18h ago
Water temp10.3°C
ClarityClear
Weather22°C
WindE 3 km/h
Pressure1011 hPa
Rain · recent0.0 mm
Rain · ahead0.0 mm

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

Water temperature for Rainbow Trout
Ideal
10°C est.ideal 1018°C
0°14°28°
How to fish it · for Rainbow 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 temperature particularly in your favour.
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

Top prey shown — see all 2 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
1
2
2
2
2
2
2
2
2
2
2
1
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
Rainbow Trout fly box
Permits & access
Permit required — see local rules.
  • Montana licence
  • Bull trout must not be targeted and must be released (federally threatened)
  • Fishability is set by the Libby Dam release, not the weather.
What's coming
Plan ahead
5-day outlook
Gallery · 2
  1. Kootenai River — 18205 Lake Koocanusa
    18205 Lake Koocanusa
  2. Terrain map of the venue
    Terrain map
About this water

The Kootenai below Libby Dam is big, cold tailwater — huge volume, steady release-driven flow, and rainbows that grow heavy on the year-round chill. It fishes on the dam's terms: watch the release out of Libby, not the clouds. Long drifts of nymphs and midges do the day-to-day work, with good Caddis and Baetis when the season turns. The scale takes getting used to — this is one of the largest trout rivers in Montana, and the current means business.

Under the surface

The Kootenai below Libby Dam is a big, cold, powerful tailwater — one of the largest-volume trout rivers in Montana, running broad and green-grey over a gravel and boulder bed through timbered northwest mountains. Libby Dam, backing up the long reservoir of Lake Koocanusa, decides the flow, so the river runs on a release schedule rather than the weather. Below the dam it pushes through even glides and long riffles toward the thunder of Kootenai Falls, the fish growing fat on the steady cold flow. This is heavy water: the wadeable margins are good, but the main current is strong and the river is bigger than almost anything else in the region.

Wading: Very high volume; strong main current below the dam

  • Mixed
  • Partly confined
  • Pool riffle
Conservation note

Wild rainbow trout (including native redband lineage) are the headline. Native westslope cutthroat and federally threatened bull trout are also present: bull trout must not be targeted and must be released unharmed. The pack's 'cutthroat_trout' profile is a Phase 1 deliverable and there is no bull_trout scoring profile by design.

Water quality · US Clean Water Act
  • Aquatic lifeImpaired
What this classification means

EPA ATTAINS assessment unit 'Kootenai River' (MT76D001_010), 2021 Integrated Report. Aquatic Life use: Not Supporting. Listed impairment causes: Temperature, Hydrologic Alteration. 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) · MT76D001_010

The full read · show the working · for Rainbow Trout · confidence 90%
How the 84 is built — score × weight = contribution
Temperature100 × 28%28.0
Flow80 × 22%17.6
Clarity85 × 18%15.3
Feeding Time80 × 13%10.4
Pressure75 × 7%5.3
Insect activity66 × 12%7.9
Conditions total= 85
Can you trust it?
Water temperatureair-to-water estimateestimated
Level / flowon-river gaugeobserved
Prey activitymodelled from regional profilemodelled
Directions
Seasons & zones
  • Trout 1 January31 December
Related guides
Booking & contacts