It has a maximum surface of 1052 ha, the longest distance between opposites shores reaches 30 kilometres (19 mi), and the total volume of the reservoir is 91 hm³.

The second and present dam, built in a period of 12 months, began its service in 1971.

Belonging to the Canal de Isabel II public company, it regulates the flow of the Manzanares river and an important part of the water supply to the city of Madrid and its surroundings.

Smaller rivers Samburiel and Arroyo del Mediano also flow into the reservoir, which is part of the natural protected area called Parque Regional de la Cuenca Alta del Manzanares.

It is also part of the Site of Community Importance (SCI) Manzanares basin, with code ES3110004.