Springs rise out of the ground
The torrent’s energy was formerly used to power a saw, a butter churn and more importantly the village mill which gave the stream its name. Like most torrents flowing through Ayer and Mission, the mill stream rises at the junction of two geological layers at an elevation of 2200 m. These torrents rise from the ground with a steady volume of discharge, then wind their way downhill forming swamps typically full of big clumps of sedges, a graminoid plant whose roots survive in 6°water. Moyes, as swamps or wetlands are often called, are usually formed by the confluence of several streams.
All villages are built near a torrent
Mountain torrents, follow the downward slope and steadily erode the surface into small rill channels that direct their flow. Nearby plants benefit from this steady water supply. To irrigate meadows and fields, transversal canals were built that became known as Valais Bisses. Water could be drawn from these canals according to a set schedule. Woe to anyone who exceeded the allotted time ! The reason why villages were built near a stream was that in addition to power and irrigation the water was needed to water the cattle and to do laundry. The butcher’s shop and the dairy were situated near the torrent because water was needed to wash premises and tools. To keep produce cool villagers placed it in containers which they would immerse in the cool stream.
An ecosystem adapted to the stream gorge
Rumbling, bubbly and foamy waters fill the gorge which is formed by the stream. The air remains cool and gets even colder in the evening, when cold air, which is heavier than warm air, is drained from surrounding mountains. Within a few tens of metres the temperature drops by some 10°. Tracks on the riverbanks are evidence of abundant wildlife coming to drink at nightfall. It is well known that larger streams are used by trout to reach distant Alpine pastures. Plants adapted to conditions of moisture, coolness and shade thrive. Two examples are white butterbur (Petasites albus) easily recognized by its broad leaves, and masterwort (Peucedanum ostruthium).
You will see the stream again further up. It crosses a road under which a tank gets filled when a sluice valve is closed, thus providing water storage in case of fire. From its source to the Navizence river, the “Torrent du Moulin” is less than two kilometres long, but that was long enough to enable the establishment of Ayer village.
Texte : Manu Zufferey, hiking guide