Le Boilet is the only stream to flow through the municipality of Hautecour. Diverted from its initial course in the past, it was used as a headrace to supply water to the sawmills and other mills in the hamlets of Le Villard et Les Moulins. Along some stretches, it strayed off course, creating little ponds called nays, which the community used for soaking hemp. Water from the stream was also used to put out fires, water crops, for livestock to drink and for chores. Since 1990, it has been deviated to supply La Trappe lake.