Madrid Water Reservoirs: Pantano de Santillana, Pantano de San Juan, and Pantano de Jarosa

Category: Madrid

Madrid, Spain has a number of water reservoirs and dams located in and around the city. These structures help to capture the water from many of the local waterways, water that is stored and later used for a variety of purposes throughout the region. Below we will take a closer look at three of these reservoirs—the Pantano de Santillana, Pantano de San Juan, and Pantano de Jarosa—and provide some key facts regarding each of them.

Pantano de Santillana

The Pantano de Santillana (Santillana Reservoir), also known as the Reservoir of Manzanares el Real, is situated in the northwest portion of the Community of Madrid (Spain), located near the Sierra de Guadarrama Mountain Range in the municipalities of Manzanares el Real and Soto del Real. The reservoir, which now has a total capacity of 91 cubic hectares (224 acres), is formed by a dam that was first built in 1907, but later reconstructed in 1969 as part of a project that roughly doubled its capacity.

The new dam was constructed in just over a year, officially opening in early 1971. It is made from a combination of materials, including asphalt and rubber, and has a total height of 40 meters and a length of 1,355 meters.

The main source of the Pantano de Santillana is the Rio de Manzanares (Manzanares River), which also flows through the city of Madrid before finally dumping into the Jarama River to the south. Other waters contributing to the reservoir include the Samburiel River and Medium Brook, among others. The reservoir is part of the protected area of the Regional Park of the High Basin of the Manzanares and the water it contains is used for both supply and hydro-electricity.

Pantano de San Juan

Pantano de San Juan, or the San Juan Reservoir, is located in the southwest region of the Autonomous Community of Madrid, in the municipalities of San Martin de Valde Iglesias, El Tiemblo, Cebreros and Pelayos de la Presa, southeast of the city of Avila, Spain. The reservoir is formed mainly by the Rio de Alberche (Alberche River), a tributary of the larger Tagus River, but also by the Cofio, a tributary of the Rio de Alberche.

One of the oldest reservoirs in the Madrid region of Spain, the Pantano de San Juan is supplied by a dam built in 1955. It has a total storage capacity of 138 million cubic meters, and occupies an area of roughly 650 hectares (1600 acres), spread lengthwise along a narrow valley, near the port of San Juan. At its peak, the dam has a height of 78 meters.

Although the Pantano de San Juan is used primarily as a water source for the southeast region of the Community of Madrid, one of its other functions is to divert water to the city of Toledo, Spain, through an artificial channel called the Picadas-Toledo Transfer.

Pantano de Jarosa

The Pantano de Jarosa, or Jarosa Reservoir, is located in the municipality of Madrid de Guadarrama, situated in the valley of La Jarosa. The smallest of the reservoirs in the Sierra de Madrid, it has a total capacity of 7.2 million cubic meters and occupies an area of approximately 55 hectares (136 acres).

Pantano de Jarosa was constructed in 1968, in line with economic policies of the time requiring hydroelectric power. The reservoir’s main source is the Jarosa Stream, although it also receives water from the Cerradillas. To contain these waters it was necessary to build two dams, one to cut the flow of the Jarosa Stream and another to prevent the overflow into the header source, the Cornejo Brook. In addition to supplying hydroelectric power in the region, the Pantano de Jarosa is also the sole water source for the town of Guadarrama and the neighboring municipalities of Alpedrete, El Escorial and San Lorenzo de El Escorial.

La Jarosa, as the reservoir is familiarly known throughout the area, is a popular weekend locale for both residents and tourists seeking to escape the noise and pollution of the city in favor of the peace and tranquility of the Jarosa Valley. It is also a hot spot for local fisherman, as the reservoir is regularly stocked with trout and other species, including pike and black bass, although the latter two populations are becoming harder and harder to find.