Freestone · Mixed · Wyoming, US

Lamar River

The Lamar River winding through Yellowstone's Lamar Valley

The Lamar Valley, with Slough and Soda Butte feeding in, holds wild, free-rising Yellowstone cutthroat in country that still feels like wilderness.

Fair · Cutthroat Trout
Parachute Adams · 16-20
Fairlive now
A side-water session, not the main event
Low and clear — careful approach country. Long leader, small flies, slower casts.
75% confidence
What moved it
  • Level0.32 mLast reading 2h ago
  • Water temp5.8°C
  • ClarityClear
Today's fly
Parachute Adams
Parachute Adams16-20
Proven pattern for this period
Conditions on the water
Live gauge
Level
Steady
0.32 m
Last reading 2h ago
Water temp5.8°C
ClarityClear
Weather0°C
WindSE 8 km/h
Pressure1029 hPa
Rain · recent0.0 mm
Rain · ahead0.0 mm

Live readings only. Trends shown where the gauge supports them.

Water temperature for Cutthroat Trout
Cool — slow
5.8°Cideal 9–15°C
0°14°28°
How to fish it · for Cutthroat 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 water temperature could be better.
Likely species
Hatch timeline · todayPeak at 10am

Hatch predictions

Today's headline hatch shown — see all 4 active hatches hour by hour as a supporter.

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Beyond the hatch · worth watchingambient prey(1)

Hatch predictions

Supporters see what else is on the menu.

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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
Brown DunHatch
2
3
3
3
3
3
3
2
Western Green DrakeHatch
2
2
Flav (Small Western Green Drake)Hatch
2
3
2
Mahogany DunHatch
2
2

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

Ranked for today
Cutthroat Trout fly box
SD
Sex Dungeon
2-6 · Pattern
Proven pattern for this period
Permits & access
Permit required — see local rules.
  • Yellowstone NP licence and native-cutthroat rules (often barbless catch-and-release) — check current NPS regulations.
What's coming
Plan ahead
5-day outlook
Fishing better nearby · 5
Gallery · 2
  1. The Lamar River winding through Yellowstone's Lamar Valley
    Lamar River, Yellowstone National Park
  2. Terrain map of the venue
    Terrain map
About this water

The Lamar Valley, with Slough and Soda Butte feeding in, holds wild, free-rising Yellowstone cutthroat in country that still feels like wilderness. It's a terrestrial game from mid- to late summer once the river clears — hoppers, ants, beetles to fish that want to eat off the top. A summer storm can turn it to chocolate milk for days, and there's no arguing with that. This is native-species water under Park regulation; treat the cutthroat as the irreplaceable things they are.

Under the surface

The Lamar runs through the closest thing Yellowstone has to the Serengeti — a wide, open glacial valley of grassland and sage where the bison graze and the wolves work the far slopes. It's a freestone river of the high country, snowmelt-fed and unregulated, brown with runoff into July and then dropping into a clear, gravel-bottomed meander that braids across the valley floor. This is native Yellowstone cutthroat water, and the fish are everything the cutthroat is supposed to be: willing, beautiful, and not always as easy as their reputation when the valley wind is up and they're sipping hoppers along the cut banks. The bed is rounded volcanic cobble and gravel; the banks are grass and undercut sod. Wading is straightforward when the river's down, and the whole business of fishing it is half watching the water and half watching the wildlife.

Wading: High off color runoff into July

  • Mixed
  • Unconfined
  • Pool riffle
  • Meandering
Conservation note

Primary species is native Yellowstone cutthroat (Oncorhynchus clarkii bouvieri). A 'cutthroat_trout' species + scoring profile is a Phase 1 deliverable; until added it will not score.

The full read · show the working · for Cutthroat Trout · confidence 75%
How the 64 is built — score × weight = contribution
Temperature46 × 28%12.9
Flow80 × 22%17.6
Clarity85 × 18%15.3
Feeding Time55 × 13%7.2
Pressure75 × 7%5.3
Insect activity47 × 12%5.6
Conditions total= 64
Can you trust it?
Water temperaturelive gauge readinggauge
Level / flowon-river gaugeobserved
Prey activitymodelled from regional profilemodelled
What would change the calculation
Warmer water — toward the 9–15 °C ideal band — would lift the temperature score.
The dawn and dusk windows score higher than the midday lull.
Directions
Seasons & zones
  • Trout Saturday of Memorial Day weekend → First Sunday in November
Related guides
Booking & contacts