Switzerland increases Lake Lugano discharge to support Lake Maggiore

Switzerland is opening the taps on Lake Lugano to help prop up Lake Maggiore. It is an emergency solution that, more than any set of figures, shows how sensitive the water situation in northern Italy has become: more water will be released from the Ceresio towards Ponte Tresa, with the aim of supporting the level of Lake Maggiore and, above all, guaranteeing supplies for the rice fields on the plain.

The discharge will rise from the current 3 to 8 cubic metres per second. The two lakes are connected and a significant share of the extra water will flow into Lake Maggiore.

The measure was discussed within the Italian-Swiss Bilateral Consultation Body on the regulation of Lake Maggiore’s levels and the management of water resources in its basin, convened urgently by the Ministry of the Environment on the basis of data from the Po River Basin Authority. The Italian delegation, made up of representatives of the ministry and the Lombardy and Piedmont regional authorities, accepted the Swiss proposal, which could be implemented as early as today.

Switzerland’s help and the ‘short blanket’ problem

The decision taken by Canton Ticino is temporary and will be reassessed in the coming days, but its significance goes well beyond this one-off intervention. The underlying problem is that the available water is no longer sufficient to meet all needs at the same time.

On the one hand are the rice paddies of Piedmont and Lombardy, which at this stage of the season need large volumes of water. On the other are the water supply networks, rivers, lakes and ecosystems, all having to cope with ever lower flows.

It is the classic “short blanket” situation: if you increase the provision for one sector, you have to check what is left for the others. And when the overall resource shrinks, even a seemingly technical decision on how to regulate a lake becomes a strategic issue.

The case of Lake Maggiore is particularly telling. Back in July, the Po River Basin Authority was already warning that the lake was close to its minimum operating level, while agriculture in Piedmont was among the sectors under greatest strain.

The problem is not confined to irrigation water for farmland. In several parts of Italy, scarcity has also started to affect drinking water supplies.

Lake Maggiore, who is in charge?

Lake Maggiore is a transboundary basin, shared between Italy and Switzerland, but its regulation is not by joint management in the strict sense. The lake level is controlled by the Miorina dam at Sesto Calende, on Italian territory, and day-to-day management is entrusted to the Ticino Consortium.

Italy and Switzerland nevertheless discuss and coordinate decisions within the Italian-Swiss Bilateral Body, because changes in the lake’s level have consequences on both sides of the border.

The picture is even more complex because the Lake Lugano, also shared between the two countries, is linked to Lake Maggiore via the River Tresa: it is through this system that Switzerland is now providing support, by temporarily increasing flows from 3 to 8 cubic metres per second. So Lake Maggiore is regulated in Italy, but managing the water resource cannot be done without coordination with Switzerland.

Water tankers fill supply gaps

Figures from Arpa Piemonte painted an equally worrying picture: surface water resources were 37 per cent below the seasonal average, while in the first ten days of July many gauging stations were showing deficits of more than 40 per cent. At Isola Sant’Antonio, the Po had an average flow of just 62 cubic metres per second, 75 per cent below its historical reference value.

The heat has made matters worse. June 2026 in Piedmont was marked by temperatures far above the average, with a regional anomaly of about +3.5 °C. Higher temperatures increased evapotranspiration, causing soil and vegetation to lose water more quickly.

The crisis spreads across the Po basin

Piedmont, however, is not an isolated case. The problem affects a far wider area.

At the end of July, the permanent observatory on water use in the Po River District raised its assessment of water stress from “medium” to “high”. Flows in the Po had progressively fallen to values below those typical of low-water conditions, and the drought index was indicating severe conditions across most monitored sections, with an “extreme” situation recorded at Cremona.

As early as 21 July, the Basin Authority was reporting problems not only for agriculture but also for water destined for households. In Lombardy, 50 municipalities were struggling, 17 of them supplied by tankers; in the Marche region there were 32. Critical situations were also reported in Veneto and Piedmont.

The picture also includes the Po Delta, where reduced river flows increase the risk of saltwater intrusion from the sea. When the river carries less freshwater, saltwater can push further inland, putting ecosystems, farming activities and water supply installations under strain.

Rice fields, drinking water, rivers: who comes first?

This is where the real issue emerges. The emergency is not just about “how much water there is”, but how to distribute it when there is not enough.

Agriculture needs irrigation precisely during the hottest phases of the year. The rice fields of Piedmont and Lombardy are among the most exposed sectors, and Piedmont is one of the areas where the region has most clearly flagged the risk of crop losses linked to limited water availability.

But that same water is needed for water supply networks, to maintain minimum flows in rivers, for ecosystems, for certain industrial uses and, in some areas, for energy production.

Hence the growing need for increasingly sophisticated interventions and agreements between regions and countries. The release from Lake Lugano towards Lake Maggiore is a concrete example: a resource available in one basin is temporarily used to support another water system in difficulty.

And in the South the problem has not gone away

The water crisis, however, is not confined to the North. Conditions vary from region to region and not all of Italy faces the same situation at the same time, but vulnerability remains high, especially in Mediterranean areas and in regions that depend heavily on reservoirs.

ISPRA monitors the severity of water stress in the various Italian districts and defines the “high” scenario as a situation in which, despite preventive measures, the resource may not be sufficient to avoid damage to the system.

It is a snapshot that helps explain why water is becoming one of the most sensitive issues in land management: it is no longer enough to wait for rain. Reservoirs are needed, along with more efficient networks, reduced losses in water supply systems, reuse of treated wastewater, less wasteful irrigation systems and planning that takes account of increasingly variable water availability.