The Barrage de Moiry is one of a number of very large dam systems that Switzerland has built in upper alpine valleys, to produce electricity and reduce flooding. This dam was built in 1958 after 4 years of construction by 1,200 workers.
The view above shows the path ascending the slope, after crossing the dam.
The alp plateau was formed by a glacial end moraine. The lake is visible in the photos, along with the Moiry glacier, receding in the background.