The Napoleonic cadastre was established in 1833 for the town of Petit-Villard. It does not present a dam as a construction, however, one notices at the exit of the lake, a relatively straight conduit, towards the overflow, comparable to a form of channel.
(extrait du cadastre napoléonien – AD39 – 3P plan 6317)
For the construction of the wooden dam, the owners agreed to flood their land in 1866.
Before 1868, “Mr. CHAVERIA Placide, PERRIN, BESSON Auguste and VUILLERMOZ all four, having factories on the reach of Héria” were “owners of the dam established at the origin of the outlet of Lac d’Antre. They joined forces to contribute to the costs of setting up the outlet of Lac d’Antre. This deduction is useful to all the machinists of the reach of Héria indiscriminately. They have hoped and still hope that they will meet with them to bear the charges which they have initiated. ”
In December 1868, the dam was described as follows: “The purpose of the dam, established across the lake’s discharge channel, is to retain above the usual level a volume of water two meters in height that the millers , bordering the reach of Héria, can use in times of drought. The structural dam is established at the origin of the outlet of the lake; the threshold is placed flush with the bottom of this stream, that is to say at a level well above the thalweg of the lake; the ridge is flared two meters above the threshold. The water can only flow into the landfill by means of a valve 1.09m wide by 0.55m high. ” “The valve retaining the waters of the lake is constantly lifted in times when the reach of Héria is no longer supplied by sources called black wells and white wells so that the millers can benefit from the flow of water” (1 ).
According to deeds of sale of July 31, 1866 and September 11, 1867, passed before Maître MONNET, notary in Moirans-en-Montagne, the former owners of the lake, gave the right to the factory owners of Villards-d’Héria to establish the dam current whose crest must be 1.30m below the benchmark sheet sealed in the rock and the threshold at 3.30m against the bottom of the same sheet. The factories can thus build up a reserve over a height of 2.00 m, giving them 165.005 m3.
(photo Le Pennec September 1989)
(1) AD39, Sp140, Chapelan Siméon factory in Villards d´Héria, minutes of site visit December 4, 1868