Val di Lei: The Dam of the Alps that “Powered” Italy

In the early 1960s, a dam also contributed to the “economic miracle” of Italy. Nestled among the Alps of Sondrio, precisely halfway between Italy and Switzerland, the Val di Lei dam “lit up the lights” of Milan and Lombardy, ensuring the energy supply needed to drive the engine of one of the richest regions in Italy.

The story of this infrastructure project is timeless, not only because of the unique characteristics of the design and the techniques used in its construction, but also for the impact it had and continues to have on both Swiss and Italian development. The most recent intervention on the occurred in 2022, when a massive photovoltaic system consisting of 1,000 modules was installed on the dam wall, capable of producing approximately 380 megawatt-hours of electricity annually. The structure, which covers 550 meters of the dam wall, alone ensures the energy supply for 160 homes in Zurich. While the intervention has a limited impact compared to the dam’s full energy potential, it perfectly reflects the spirit of this project, which for over sixty years has continued to serve as an energy lifeline for both Italy and Switzerland.

For Italy and its development, the Val di Lei dam played a central role. In the 1960s, the country experienced its peak economic growth since the end of World War II, leading to a surge in energy demand that exceeded the country’s production capacity. This led to the need to import energy from abroad. A solution to this need came from the bilateral agreements signed with Switzerland in 1955. According to these agreements, 20% of the Val di Lei dam‘s production would be allocated to Italy, in addition to the 30% of gross hydropower guaranteed by the agreements signed in 1948.

The dam itself, from the moment of its construction, had been the subject of a pact between Italy and Switzerland. The land on which it was built was initially Italian but was ceded to Switzerland in exchange for land further north. However, the agreements stipulated that a portion of the Val di Lei dam‘s production would still be directed to Italy.

The dam is part of the Alto Reno Posteriore (Hinterrhein) hydroelectric complex, which includes three power stations that produce 1.325 billion kWh of energy annually. Therefore, when it became operational in 1962, Lombardy (thanks to its energy supply) became the second region in Italy for kWh production, after Trentino-Alto Adige, and by the following year, its energy production was able to cover over 67% of the national energy demand.

Beyond its energy aspects, the construction of the Val di Lei dam and the creation of the large artificial lake had a significant impact on tourism. The lake, located in the municipality of Piuro, in the province of Sondrio, at an altitude of two thousand meters, quickly became a sought-after destination for mountain enthusiasts.

Despite the infrastructural work, the entire area remained unspoiled and became a reference point for skiers in winter and campers in summer. The valley is accessible by car from Switzerland, while from Italy, it can only be reached on foot, either by climbing the Angeloga Pass or other smaller passes. To accommodate tourists, parking areas for campers were set up at the top of the dam, as well as a dedicated Educational Center with photographs, descriptive panels, and construction artifacts. Behind the dam lies the artificial reservoir, considered one of the most beautiful lakes in the Alps due to its blue waters and rich fish fauna, making it an attraction for fishing enthusiasts as well. During the fishing season, typically from June to September, the lake’s shores are dotted with fishing rods and lines.

The effects of the Val di Lei dam, which benefit two countries today, stem from the incredible work carried out in the 1950s by Girola and Lodigiani, the two companies that built the dam and later merged into the Webuild Group.

Constructing an infrastructure like this at an altitude of two thousand meters, in the heart of the Alps, was a highly complex endeavor. Before work began, the construction site could only be accessed on foot, so two 15-kilometer cable cars were built, one for transporting people and the other for materials. On the northern side, a road and an access tunnel to the construction site were built, and a village capable of housing 1,500 workers was established for personnel accommodation.

Work began in 1957 and was completed in 1960, three years ahead of schedule. Once finished, this engineering masterpiece stood as Switzerland’s fifth-largest dam by reservoir size (197 million cubic meters), with a length of 690 meters and a height of 141 meters. To build it, 2.2 million quintals of cement were used, double the weight of the Milan Cathedral, making it, in effect, a cathedral of engineering, another timeless work that continues to fuel development and well-being today.