Freestone · Limestone · Jura, FR

Héria

Héria terrain map

The Héria is classic Jura water on a small scale: a limestone stream with the clarity and temperature stability of a proper chalk river, where the trout live long enough to learn every fly in the box and are perfectly happy to show you they've done so.

Poor · Brown Trout
Pheasant Tail Nymph · 14-18
New ruleReported 9 Sept 2026

Severe drought restrictions (alerte renforcée) in force

VigiEau lists this venue's surface-water zone (Haute chaîne, dépt 39) at alerte renforcée, under an official préfectoral drought arrêté. Fishing is not itself banned by it, but water levels are low — go gently on stressed fish.

Arrêté préfectoral n°38076 ↗

Temporary notices from official orders and recent fishery reports — they clear automatically once out of date. Always confirm locally before travelling.

Closed season
Out of season. Try elsewhere.
Closed — confidence not applicable today.
What moved it
  • LevelProxyvia Bienne
  • Water temp13.5°C
  • ClarityClear
Today's fly
Pheasant Tail Nymph
Pheasant Tail Nymph14-18
Upstream
Conditions on the water
Proxy gauge
Level
Steady
Proxy
via Bienne
Water temp13.5°C
ClarityClear
Weather14°C
WindSE 9 km/h
Pressure1021 hPa
Rain · recent0.0 mm
Rain · ahead7.4 mm

No gauge on this water — conditions are inferred from Bienne. The trend transfers, the absolute level does not.

Water temperature for Brown Trout
Ideal
14°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.
Likely species
Mayflies
Caddisflies
Gammarids
Hatch timeline · todayPeak at 11am

Hatch predictions

Today's headline hatch shown — see all 12 active hatches hour by hour as a supporter.

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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 2 as a supporter.

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Evidence
Survey-backed · regionalHigh confidence

Backed by regional invertebrate surveys; no sampling on this exact reach yet.

Through the year
0–3 scale · September highlighted
J
F
M
A
M
J
J
A
S
O
N
D
Trout seasonSeason
1
2
2
2
2
2
1
Evening SedgeHatch
2
3
3
3
2
Large Dark OliveHatch
1
2
2
1
Iron BlueHatch
1
2
2
2
2
2
2
1
Blue Winged OliveHatch
1
2
2
2
2
1

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

Ranked for today
Brown Trout fly box

Sight-nymphing and technical dry-fly fishing on very clear trout and grayling rivers, with strong mayfly and sedge windows and highly selective fish.

SS
Small Streamer
6-10 · Pattern
Swing
What's coming
Plan ahead
5-day outlook
Other water nearby · 5
Lac de Vouglans
8.0 km
Rainbow trout · Brown trout
Bienne
9.0 km
Brown trout · Grayling
Les Truites des Rivières
23 km
Rainbow trout
Valserine
24 km
Brown trout · Grayling
Lac des Rousses
28 km
Brown trout · Rainbow trout · Grayling
About this water

The Héria is classic Jura water on a small scale: a limestone stream with the clarity and temperature stability of a proper chalk river, where the trout live long enough to learn every fly in the box and are perfectly happy to show you they've done so. The fish are wild, the water is transparent, and the upstream dry-fly drill is the only way to fish it with any self-respect. Work upstream in short, precise casts, keep out of the water when you can, and treat every presentation as if it's your only one. Olives in spring, caddis through June and July, terrestrials in the low water of late summer. This is not a numbers river. It's a river where you go home remembering three fish in detail because each of them required something specific from you.

  • Limestone
Water quality (WFD)
  • Ecology: Good
  • Chemical: Unknown

WFD classification · FRDR11905

The full read · show the working · for Brown Trout · confidence 75%
How the 0 is built — score × weight = contribution
Temperature100 × 28%28.0
Flow80 × 22%17.6
Clarity95 × 18%17.1
Feeding Time40 × 13%5.2
Pressure80 × 7%5.6
Insect activity53 × 12%6.4
Conditions total= 80
Can you trust it?
Water temperatureair-to-water estimateestimated
Level / flowproxy via Bienneproxy
Prey activitysurvey-backed invertebrate datasurvey
What would change the calculation
The dawn and dusk windows score higher than the midday lull.
Directions
Apple MapsGoogle Maps
Seasons & zones
  • Trout 2nd Saturday of March → 3rd Sunday of September
Related guides
Pyrenees PlaybookFrench riversEuro Nymphingsubsurface methods
Booking & contacts