Pontón de la Oliva dam-Project Management

Pontón de la Oliva is a dam located in the northeast of the Community of Madrid, Spain. It is a gravity dam built in the nineteenth century in the traditional masonry style with 27 meters of height and nearly 74 meters of length.

At that time Madrid was a small town which population was growing fast due to its condition of capital in the kingdom of Spain, surpassing the 200.000 citizens. As we can observe, despite the Manzanares River, the site where Madrid is located is limited in water, not enough to supply its population.

Construction of the dam

Although the search for reserves as nearby springs and the digging of wells to access groundwater was constant, the increasing demand required a new way of drinking water supply. It was not until 1848 when the civil engineers Juan Rafo and Juan de Ribera presented a draft of the project, which explain to the then Trade, Education and Civil Works Minister, Bravo Murillo, how to bring water from the Lozoya River to the capital.

Juan Rafo and Juan de Ribera

The plan was approved in 1951 and in that same August, the first stone was laid in the foundation of the dam in the Lozoya River in the presence of the king consort Francisco de Asís de Borbón.

Francisco de Asís de Borbón, laiding the first stone

The location of the dam was determined by the distance traveled, the maintenance of a minimum slope and the flow of water transported. Lozoya basin, for its proximity to Madrid and its capabilities, made the Pontón the most convenient location at 77 km from Madrid, with a difference in height of 26.46 meters. The conduction of water was planned for a flow of 0.38 m³/sec. with the possibility of an increase to 2.25 m³/sec. if necessary.

Regarding funding, the budget made by the engineers estimated an expenditure of 60 to 80 million “reales”, the then official coin1, for water canalization and distribution. 25 would be for distribution, 7,5 for the aqueducts, 8 for construction of mines and the dam, 2,5 for the tank storage in Madrid and the rest for compensation, contingency and administrative expenses and supervision of works.

Seven years later, the 24TH of June of 1858, the Queen Isabel II inaugurated in San Bernardo Street the first channel which brought the so longed water to Madrid. The event was the opening of the first system of the company “Canal de Isabel II”.

Isabel II, inaugurating the «Canal de Isabel II»

The final budget of the project has increased 127 million “reales” instead of the 80 million expected. The working force was an amount of more than 400 animals, 1500 prisoners of the Carlist Wars, 200 free workers and 200 craftsmen, who suffered from the hard working conditions and the cholera outbreak which spreaded in the camp site.

However, the biggest problem of the project was the terrain features. The dam was located on karstified limestones that are unable to retain the water due to a continuous and abundant leakage.

The engineers didn’t take this into account, even though they were informed beforehand by Casiano de Prado, an experienced geologist and mining engineer.

As a result the dam was useless from the first moment of its construction and, two years later, in 1860 the channel was extended upstream and a new one was built, the Navarejos dam.

1 The real was a Spanish silver coin. It’s equivalent in euros can be more or less  0, 24 euros.


To obtain further information (if you know Spanish or you are patient enough to use a translator) you can check the links below:

Urban Idade. Memories of urban networks

Canal de Isabel II. History

Fotonazos. With pictures

Or just write «Pontón de la Oliva» in Google… Enjoy it!


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