The permitted range
Navigation on the Viroin is allowed between 1.6 and 23 m³/s, measured at the Treignes station. Below the minimum, the rocky bed breaks the surface; above the maximum, the flood current is too powerful. The reading at the top of the page compares the measurement with these two thresholds.
Reading the river flow
Only the two thresholds above have legal force. The bands below are indicative: they describe what you meet on the water, not what the authority allows.
| Flow (m³/s) | Conditions | Key point |
|---|---|---|
| Under 1.6 | Too low | Navigation forbidden: the rocky bed and aquatic life are protected. |
| 1.6 to 5 | Very calm | Rocky bottom sometimes visible; better for experienced paddlers. |
| 5 to 15 | Ideal conditions | Clear water, steady current, accessible to everyone. |
| 15 to 23 | Steady current | Faster trip; beginners should stay alert. |
| Over 23 | Too high | Navigation forbidden: flood flow. |
Why the river can stay closed
The official status is based on the average flow over the last 72 hours, not on a single measurement. But the SPW can also ban navigation by ministerial order, even when the flow is sufficient. In that case, the river reopens as soon as the ban is lifted, announced by the SPW. The reading at the top of the page shows the official status, checked regularly.
Station and regulations
The reference flow comes from SPW station 9021, at Treignes, on the Viroin stretch, a small tributary of the Meuse in the Viroin-Hermeton Nature Park. The thresholds are in Annex 2 of the Walloon Government decree of 19 March 2009, and the day’s status follows from them (Article 6). An overview of the other rivers is on the navigable flows in Wallonia page.
Safety
- Cold water or cool air: life jacket fastened, windproof jacket, fleece and a change of clothes kept in a waterproof barrel. A capsize chills you fast.
- Rain: waterproof jacket and belongings kept dry in a waterproof bag.
- Wind: gusts make paddling more tiring into the wind.
- Fog: stay together and spot obstacles earlier.
- After heavy rain: the flow can pass the maximum even under a clear sky.
Nearby rivers
The Viroin flows into the Meuse: see the Meuse page. If the river is closed, the Semois and the Lesse have their own thresholds and may stay open.