The San Juan reservoir is located in the municipalities of San Martín de Valdeiglesias, El Tiemblo, Cebreros and Pelayos de la Presa, in the southwestern corner of the Community of Madrid and south-east of Ávila, in Spain. It includes the waters of the Alberche River, a tributary on the right side of the Tagus, and the Cofio, one of the main tributaries of the Alberche. It is accessed through the M-501, popularly known as the "road of the marshes."
The San Juan reservoir is used to supply water to the southwestern area of the Madrid region, as well as for the generation of electricity. Together with these uses, it fulfills a recreational and sporting function, which has made it a very popular place for tourists and hikers.
It is the only reservoir in the Community of Madrid where bathing and water-powered activities are allowed, in addition to other water sports such as water skiing or wakesurfing. The marsh has a total of 14 km of beaches.
Its enclave - in the midst of extensive pine pine forests, in the foothills of the Sierra de Gredos - has contributed to the development of the tourism and urban sector. Residential complexes are abundant, mainly on the right bank. Next to the reservoir there is an area where climbing is practiced, with 16 sectors and 160 routes.8
Two of the places with the highest number of visitors are the Cerro de San Esteban, located on the right bank, and the Lancha del Yelmo, on the left. Among the most outstanding recreational areas, we can mention the area of the Virgen de la Nueva and El Muro.
In the vicinity of the San Juan reservoir, both in the municipality of Pelayos de la Presa and in San Martín de Valdeiglesias there are numerous restaurants, snack bars and beach bars.