Variations in water level can occur on the river as part of normal facility operations.

Draining events occur regularly, but most often in summer, which cause floods. Small islands, gravel banks and riverbanks can be quickly submerged. Draining is necessary to prevent hydropower facilities becoming clogged with sand. These flushes allow silt and sediment to be evacuated downstream. In order for these purges to be effective, a large flow of water is released into the river over a fairly short period. This means that watercourses downstream of hydropower structures remain unsettled over a long period and see their flow increase and decrease during the day and night. In order to minimise the risks, Electricité d'Emosson SA does everything possible to carry out these purges at night, however, there are situations which mean purges have to be performed during daytime as well, which is especially the case during summer.

When hiking along such rivers, you must always adopt a cautious attitude and avoid being within the river or on its banks.

The Emosson reservoir can play a key role in protecting against floods in the Rhône valley. The dam can absorb a large portion of precipitation, depending on how full it is, and then attenuate the effects of flooding downstream. Although safety imperatives may conflict with economic imperatives, protecting people and property is Electricité d'Emosson SA’s highest concern during these natural events.