Northern Italy is drying out. Will water from Switzerland save Italian rice?

The extremely low water level in Lake Maggiore and the worsening drought in northern Italy have prompted Italian and Swiss authorities to take emergency action. The outflow from Lake Lugano has been increased from 3 to 8 m3/s. Will that be enough to provide relief for the drying rice fields?

Drought in Italy lowers Lake Maggiore levels

Northern Italy is facing water shortages. On 6 August, the Po River District Basin Authority confirmed a high level of hydrological risk across the entire Po River basin. The most difficult situation concerns Lake Maggiore, located on the border between Italy and Switzerland. The filling level of its retention reservoir (the water reserve available for regulation) has fallen to 5.3%, and conditions have been classified as extreme drought.

The problem is not limited to a single lake. In Piedmont and Lombardy, rainfall has been below average, while high temperatures have increased evapotranspiration, meaning water loss from soil and plants. According to Arpa Piemonte (the regional environmental protection agency), by the end of July the region’s available surface water resources were 62% below the average for that period, and Lake Maggiore was approaching its historical seasonal low levels.

The effects of the drought are also visible in water supplies for residents. As early as mid-July, around 100 municipalities in Piedmont had introduced restrictions on water use for non-essential purposes, and in about 50 towns, home to 25,000 people, water deliveries by tanker trucks became necessary.

Switzerland increases outflow through Ponte Tresa

The growing water deficit led to an emergency meeting on 10 August of the Italian-Swiss consultative body responsible for regulating Lake Maggiore and managing the water resources of its catchment. The meeting was convened at the request of the Italian Ministry of the Environment.

Initially, increasing releases from Swiss hydropower reservoirs was considered, but the canton of Ticino ruled out that option. Their reserves are close to the lowest levels recorded over the past 10 years, and part of the water resources is covered by concessions held by private operators. A decision was therefore made to temporarily increase the outflow from Lake Lugano.

Since 11 August, 8 m3/s has been flowing through Ponte Tresa instead of 3 m3/s. The operation is expected to last 10 days and, according to the authorities of the canton of Ticino, lower the level of Lake Lugano by about 10 cm.

Lake Lugano and Lake Maggiore are connected by the Tresa River

Lake Lugano, also known as Ceresio, is another transboundary lake located between the Swiss canton of Ticino and the Italian region of Lombardy. Its outflow is the Tresa River, which partly forms the border between Switzerland and Italy before flowing into Lake Maggiore near Luino.

This connection explains why the decision concerning Lake Lugano matters for the situation on the Italian side. A larger outflow through Ponte Tresa increases inflow to Lake Maggiore and then, through the Ticino River, supplies the system used by farmers and other water users in northern Italy. This is not a transfer of water between separate reservoirs but a regulation of flow within a single shared catchment.

The greatest pressure is on rice fields

The additional flow is particularly important for the agricultural areas of Novarese, Lomellina and Vercellese. This is one of the most important rice-producing regions in Europe and depends heavily on irrigation systems supplied with water from the Ticino and Po river basins.

Agriculture, however, is not the only user of this resource. Water utilities, the energy sector, industry and the environment all compete for the same water. In practice, this means making difficult decisions: how much water should be allocated to fields, how much should be reserved for residents, and how much should remain in rivers to avoid increasing pressure on ecosystems.

Who decides about water that crosses the border?

In the case of Lake Maggiore, there is no single owner. The lake, its inflows and its outflows form a shared catchment, so regulating water flows requires agreements between Switzerland and Italy. Switzerland is responsible for the infrastructure at Ponte Tresa, but the effects of the decision to increase the outflow are felt on the Italian side of the system as well.

This is the essence of transboundary water management. It is not only about technically increasing water flows, but about balancing the needs of many users. During droughts, authorities must decide how much water can be sent downstream, how much should remain in lakes and rivers, and how to reduce the risk of shifting the problem from one country to another.

The additional water from Lake Lugano will not end the drought in northern Italy, but it may temporarily reduce pressure on the Lake Maggiore-Ticino-Po system at a critical point in the irrigation season. This case shows that when a catchment is shared, national borders cannot be the boundaries of water management.