Freestone · Mixed · Montana

Jefferson River

A broad, calm stretch of the Jefferson River bordered by grassy banks and cottonwood trees, with mountains in the distance.

The Jefferson is born where the Beaverhead, Ruby, and Big Hole all come together, and it grows into a big, slow, brushy valley river that hides some genuinely large brown trout under its banks.

Poor · Rainbow Trout
Parachute Adams · 12-18
Poorlive now
Not the day for it
River steady at a fishable height. Not much stacked in your favour today. Worth an hour if you are nearby, not worth the special trip.
90% confidence
What moved it
  • Level1.09 mLast reading 23h ago
  • Water temp22.9°C
  • ClarityClear
Today's fly
Parachute Adams
Parachute Adams12-18
High-confidence seasonal pick
Conditions on the water
Live gauge
Level
Steady
1.09 m
Last reading 23h ago
Water temp22.9°C
ClarityClear
Weather23°C
WindE 3 km/h
Pressure1014 hPa
Rain · recent2.5 mm
Rain · ahead0.0 mm

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

Water temperature for Rainbow Trout
Warm — slow
22.9°Cideal 10–18°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
Water at 22.9°C. This is the line where catch-and-release kills brown trout. Do not fish for them today.
Hatch timeline · todayQuiet day

Hatch predictions

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Sub-surface · on the nymphunder the surface

Hatch predictions

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Beyond the hatch · worth watchingambient prey

Hatch predictions

Top prey shown — see all 2 with Pro.

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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 Green DrakeHatch
2
2
Flav (Small Western Green Drake)Hatch
2
3
2
Mahogany DunHatch
2
2
American March BrownHatch
2
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
  • The Jefferson is one of the first rivers to go under summer hoot-owl restrictions — check FWP before an afternoon session.
What's coming
Plan ahead
5-day outlook
Water here at 22.9°C. Nothing cooler within range.
Gallery · 2
  1. A broad, calm stretch of the Jefferson River bordered by grassy banks and cottonwood trees, with mountains in the distance.
    Jefferson River at Silver Star, Montana
  2. Terrain map of the venue
    Terrain map
About this water

The Jefferson is born where the Beaverhead, Ruby, and Big Hole all come together, and it grows into a big, slow, brushy valley river that hides some genuinely large brown trout under its banks. It's a spring-and-fall proposition. Come summer it draws down, warms up, and goes under hoot-owl restrictions as quick as anything in the region — so fish the cool mornings and the shoulders of the year, and leave the hot afternoons to somebody who hasn't read the gauge.

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

EPA ATTAINS assessment unit 'Jefferson River' (MT41G001_011), 2021 Integrated Report. Aquatic Life use: Not Supporting. Listed impairment causes: Temperature, Sediment, Habitat Alterations, Hydrologic Alteration, Metals Other Than Mercury. 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) · MT41G001_011

The full read · show the working · for Rainbow Trout · confidence 90%
How the 6 is built — score × weight = contribution
Temperature3 × 28%0.8
Flow80 × 22%17.6
Clarity85 × 18%15.3
Feeding Time40 × 13%5.2
Pressure75 × 7%5.3
Insect activity45 × 12%5.4
Limiting factor: Water temperature (22.9°C) is outside Rainbow Trout's preferred range (10–18°C)= 50
Can you trust it?
Water temperaturelive gauge readinggauge
Level / flowon-river gaugeobserved
Prey activitymodelled from regional profilemodelled
What would change the calculation
Cooler water — back toward the 10–18 °C ideal band — would lift the score and ease welfare.
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