It is an oblong lake at an altitude of 1,616 meters. The lake was formed in a glacial basin. The water in the lake is dark blue and flows into a drainage basin formed by the snow-capped mountain ranges of the Pyrenees.

The lake’s water source is the Eastern Valira and Madrid rivers. The water stored in the reservoir is used to generate hydroelectric power at a power plant located near the village of Encamp.

A 6.2-kilometer cable car leads from Encamp to the lake.