A Bilateral Emergency Decision
Climate change is hitting northern Italy hard, and in response, Switzerland has decided to open the gates of Lake Ceresio (Lake Lugano) to help its transalpine neighbor. The measure, debated in the Italo-Swiss Bilateral Consultative Body, was convened urgently to guarantee sufficient water in Lake Maggiore and ensure supply to the rice paddies of the Po Valley. The Italian delegation accepted the Swiss proposal, which took effect almost immediately and will be subject to constant reassessment in the coming days, according to Euronews.
The Po River in Critical Numbers
The situation is dire. On August 12, 2026, at the Pontelagoscuro station, the Po River recorded a flow of just 233 cubic meters per second, far below the critical threshold of 450 m³/s needed to prevent saltwater intrusion. The Po River District Basin Authority classified most stretches as in severe drought on August 13, with Cremona and Borgoforte already in extreme drought.
In Piedmont, water reserves are 37% below the average for the period, with even higher peaks in some lakes. The Po River is flowing at 75% less than usual. In July 2026 alone, the region experienced a thermal anomaly of more than 3.5°C above normal.
Key Po River Data (August 2026)
| Location | Flow (m³/s) | Status |
|---|---|---|
| Pontelagoscuro | 233 | Critical |
| Cremona | — | Extreme drought |
| Borgoforte | — | Extreme drought |
The Salt Wedge and the Blue Crab
The drop in flow allows seawater to penetrate the Po delta, a phenomenon known as the salt wedge. This saltwater intrusion not only affects drinking water extraction but is also facilitating the spread of the blue crab (Callinectes sapidus), an invasive exotic species native to the American Atlantic coasts.
According to a study published in Scientific Reports, the blue crab has already been found more than 160 kilometers from the coast, in the Mantua area, as of 2023. The species is euryhaline, meaning it tolerates wide variations in salinity, allowing it to move between sea, brackish, and freshwater. Researchers recorded catches of up to 150 kilograms of blue crabs in a single sample in the Po di Volano and Po di Goro branches between 2023 and 2024.
Algae: Another Headache
The drought and heat have also triggered an explosion of algae in the Po as it passes through Turin. The combination of reduced flow, water temperatures up to 28°C, and nutrients from agricultural and livestock waste created the perfect conditions for a green carpet of algae and aquatic plants.
The municipality of Turin has already removed more than 136 tons of algae at a cost of approximately 100,000 euros, using an excavator mounted on a barge. Among the species detected are local algae like Spirogyra and Cladophora, but also invasive plants such as Blitum nuttallianum, native to North America.
A Summer of Records
The heatwave sweeping Europe in 2026 shows no signs of letting up. The largest glacier in the Italian Alps, the Marmolada Glacier, has lost 12 million cubic meters of water in one year and has retreated 265 meters since 2023. This situation is a clear example of how climate change is transforming ecosystems and forcing countries to cooperate in unprecedented ways.
The Swiss measure, though temporary, sets a precedent in cross-border water management and offers a lifeline to a region struggling to maintain its agricultural production and ecological balance.
Sources: Euronews, Scientific Reports