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.

Today · Closed season
Czech Nymph
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Temporary notices from official orders and recent fishery reports — they clear automatically once out of date.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.

Forecast · Today
Closed season
Out of season. Try elsewhere.
75% projected
Today's fly
Czech Nymph
Czech Nymph
Conditions on the water · Today
Proxy gauge
Level
Steady
Proxy
via Bienne
Water temp7.5°C
ClarityClear
Weather-2°C
WindN 6 km/h
Pressure1016 hPa
Rain · recent16.7 mm
Rain · ahead3.9 mm

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

Water temperature for Brown Trout
Cool — slow
8°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
Gammarids
Hatch timeline · todayPeak at 11am

12pm(now) — Autumn Needle Fly

Stage: Creeping nymphsApproach: Heavy nymphActivity: 37%
Also:Black Midge31%Autumn Olive29%
Peak emergence window5 food groups active

Peak activity at 11am — Autumn Needle Fly (Autumn Needle Fly, Peak emergence window)

Sub-surface · on the nymphunder the surface

Hatch predictions

Top nymph shown — see all 4 guilds 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 · November 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
Bienne
9.0 km
0
Brown trout · Grayling
Valserine
24 km
0
Brown trout · Grayling
Lac de Vouglans
8.0 km
Rainbow trout · Brown trout
Les Truites des Rivières
23 km
Rainbow trout
Lac des Rousses
28 km
Brown trout · Rainbow trout · Grayling
About this water

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
Temperature57 × 28%16.0
Flow95 × 22%20.9
Clarity85 × 18%15.3
Feeding Time50 × 13%6.5
Pressure80 × 7%5.6
Insect activity43 × 12%5.2
Conditions total= 70
Can you trust it?
Water temperatureair-to-water estimateestimated
Level / flowproxy via Bienneproxy
Prey activitysurvey-backed invertebrate datasurvey
What would change the calculation
Warmer water — toward the 10–16 °C ideal band — would lift the temperature score.
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
At a glance

Héria is a freestone river in Jura, France. The catchment geology is recorded as limestone, and the water sits at about 741 m above sea level. The species listed for this water is brown trout. The trout season is recorded as running from 2nd Saturday of March to 3rd Sunday of September. Its Water Framework Directive ecological status is recorded as good. Nearby waters in our listings include Lac de Vouglans at 8.0 km, Bienne at 9.0 km and Les Truites des Rivières at 23 km.