And although practical, it also looks stunning. The barrage wall is decorated with a picture of the Greek Titan Atlas and drops 180 metres into a wooded valley, holding back a vast lake beneath which lies the sacrificed village of Tignes.
For Zohra Chiheb, of Notre Dame sixth-form college, Leeds, the sight is inspiring. She is one of 20 A-level students on a week-long trip to France aimed at encouraging women into engineering.
Zohra said: "The dam was great, really interesting. I liked the fresco on it because I'm doing art. Engineering appeals to me and I have looked at a few engineering courses, especially design-based ones, so that I can incorporate art."
The trip was organised by engineering charity the Smallpiece Trust and is one of several "Insight" courses held around the UK and abroad to promote engineering careers.
Nic Erskine, training co-ordinator of the Smallpiece Trust, said: "Most people have the wrong perception of what engineering really is - they think it is dirty, greasy and not suitable for women."
The course also included talks from engineers, and workshops where the girls designed a cage to keep an egg intact when dropped from a window.
Contact Insight on 0800 282167 or the Smallpiece Trust on 01926 333200