Mayflies
Stoneflies
Caddisflies
Damselflies & dragonflies
Gammarids
- Ecology: Good
- Chemical: Unknown
WFD classification · FRDR484
Rules at a glance
- Day tickets
Water temperature for Brown Trout
Ideal11°C est.ideal 10–16°C
0°14°28°
We have not characterised this dam's release, so this is a general cold-release figure and could be several degrees out in either direction. Treat it as a hint, not a reading, and check locally before you fish.
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
Damselflies & dragonflies
Hatch timeline · todayQuiet day
Hatch predictions
Today's headline hatch shown — see all 11 active hatches hour by hour as a supporter.
Start free trial14-day free trial. Cancel anytime.
Sub-surface · on the nymphunder the surface
Hatch predictions
Supporters see the full sub-surface read.
Start free trial14-day free trial. Cancel anytime.
Beyond the hatch · worth watchingambient prey(1)
Hatch predictions
Supporters see what else is on the menu.
Start free trial14-day free trial. Cancel anytime.
Evidence
Survey-backed · regionalHigh confidence
Backed by regional invertebrate surveys; no sampling on this exact reach yet.
Through the year
0–3 scale · October highlighted
J
F
M
A
M
J
J
A
S
O
N
D
Trout seasonSeason
1
2
2
2
2
2
1
Grayling seasonSeason
1
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
Fly box · Brown Trout
6-10 · Pattern
Swing
Permits & access
Permit required — see local rules.
- Carte de pêche AAPPMA.
What's coming
Plan ahead
5-day outlook
Other water nearby · 5
Gallery · 2
The River Ain near Villieu-Loyes-Mollon, on the lower Ain plain Terrain map
Water quality (WFD)
The full read · show the working · for Brown Trout · confidence 90%
How the 0 is built — score × weight = contribution
Temperature100 × 28%28.0
Flow80 × 22%17.6
Clarity95 × 18%17.1
Feeding Time70 × 13%9.1
Pressure80 × 7%5.6
Insect activity56 × 12%6.7
Conditions total= 84
Can you trust it?
Water temperatureair-to-water estimateestimated
Level / flowon-river gaugeobserved
Prey activitysurvey-backed invertebrate datasurvey
Directions
Seasons & zones
- Trout 2e Saturday de March → 3e Sunday de September
- Grayling 3e Saturday de May → 3e Sunday de September
France national rule: grayling opens 3rd Saturday of May in all waters. In 1st category (salmonid) rivers, grayling closes with the trout season on the 3rd Sunday of September. Departmental regulations may impose additional restrictions. Always check the relevant département's 2026 arrêté préfectoral.
- Coarse 2e Saturday de March → 3e Sunday de September
Chub has no national closed season of its own in France — on a 1st-category (salmonid) reach like this, ALL fishing (any species, any method) is prohibited outside the water's own open season (Code de l'environnement Art. R436-6), so chub simply inherits the trout/grayling season rather than following a separate coarse-fish law.
Related guides
Booking & contacts
Ain (lower / Plaine de l'Ain)
Water temperature for Brown Trout
Ideal11°C est.ideal 10–16°C
0°14°28°
We have not characterised this dam's release, so this is a general cold-release figure and could be several degrees out in either direction. Treat it as a hint, not a reading, and check locally before you fish.
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
Damselflies & dragonflies
Hatch timeline · todayQuiet day
Hatch predictions
Today's headline hatch shown — see all 11 active hatches hour by hour as a supporter.
Start free trial14-day free trial. Cancel anytime.
Sub-surface · on the nymphunder the surface
Hatch predictions
Supporters see the full sub-surface read.
Start free trial14-day free trial. Cancel anytime.
Beyond the hatch · worth watchingambient prey(1)
Hatch predictions
Supporters see what else is on the menu.
Start free trial14-day free trial. Cancel anytime.
Evidence
Survey-backed · regionalHigh confidence
Backed by regional invertebrate surveys; no sampling on this exact reach yet.
Through the year
0–3 scale · October highlighted
J
F
M
A
M
J
J
A
S
O
N
D
Trout seasonSeason
1
2
2
2
2
2
1
Grayling seasonSeason
1
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
Fly box · Brown Trout
6-10 · Pattern
Swing
Permits & access
Permit required — see local rules.
- Carte de pêche AAPPMA.
What's coming
Plan ahead
5-day outlook
Other water nearby · 5
Gallery · 2
The River Ain near Villieu-Loyes-Mollon, on the lower Ain plain Terrain map
Water quality (WFD)
- Ecology: Good
- Chemical: Unknown
WFD classification · FRDR484
The full read · show the working · for Brown Trout · confidence 90%
How the 0 is built — score × weight = contribution
Temperature100 × 28%28.0
Flow80 × 22%17.6
Clarity95 × 18%17.1
Feeding Time70 × 13%9.1
Pressure80 × 7%5.6
Insect activity56 × 12%6.7
Conditions total= 84
Can you trust it?
Water temperatureair-to-water estimateestimated
Level / flowon-river gaugeobserved
Prey activitysurvey-backed invertebrate datasurvey
Directions
Seasons & zones
- Trout 2e Saturday de March → 3e Sunday de September
- Grayling 3e Saturday de May → 3e Sunday de September
France national rule: grayling opens 3rd Saturday of May in all waters. In 1st category (salmonid) rivers, grayling closes with the trout season on the 3rd Sunday of September. Departmental regulations may impose additional restrictions. Always check the relevant département's 2026 arrêté préfectoral.
- Coarse 2e Saturday de March → 3e Sunday de September
Chub has no national closed season of its own in France — on a 1st-category (salmonid) reach like this, ALL fishing (any species, any method) is prohibited outside the water's own open season (Code de l'environnement Art. R436-6), so chub simply inherits the trout/grayling season rather than following a separate coarse-fish law.
Related guides
Booking & contacts