Hydropower: the challenging summer of 2026 – water levels down 40 per cent in some reservoirs
A lack of spring rain and high temperatures have put the sector under strain, although not yet to the same extent as in 2022, the year of the severe drought
Summer 2026 proved challenging for hydroelectric power. As early as May, Terna observed a 38.5 per cent fall in renewable hydroelectric generation compared with the same month in 2025, due to lower water levels. The figures for the first five months of 2026, however, are down by 19.3% overall compared with those for 2025 – a year which had already ended with a 21.2% decline when compared with the record-breaking year of 2024.
“Whilst the winter was generally rainy, the same cannot be said of the spring,” explains Francesco Avanzi, a researcher at the Cima Foundation. “This is a major problem because, along with autumn, spring is a cornerstone of the water supply. Between March and May, we saw a 30–50 per cent reduction in rainfall across the whole of the North, the area with the highest concentration of hydroelectric power stations.”
Then there are the extreme temperatures in June: “This caused the water to evaporate,” continues Avanzi, “and the snow to melt much earlier than usual – even a month ahead of schedule in certain areas. There was therefore less water in the reservoirs: it had evaporated and the snowmelt supply had dried up. The average snow-water equivalent in Italia was -14 per cent in March and almost -50 per cent in April. Rainfall, on the other hand, was +44 per cent in February, -5 per cent in March, -40 per cent in April and -32 per cent in May.”
“It doesn’t look like it’s going to be a good year for hydroelectric power,” summarises Giuseppe Argirò, CEO of Compagnia Valdostana delle Acque. “It’s too early to say how it will turn out because we’re waiting to see how July goes – the most important part of the hydroelectric season. If the snowmelt has already finished by July – given that it normally lasts longer – the season will be very challenging. At the moment, preliminary figures suggest we are below the ten-year average, although it shouldn’t be as bad as 2022: back then, June was disastrous, even more so than the one we’ve just had. The signs are negative, however, further highlighting the urgent need for investment, alongside the stabilisation of concessions through the ‘fourth way’ and discussions with the EU, hopefully after the summer.”
The situation regarding the reservoirs is not the same everywhere. Filippo Beneventi, director of Edison’s Hydroelectric Operations, explains that water levels in the reservoirs managed by the group are currently around 40 per cent below historical averages, “in a scenario reminiscent of the extremely critical conditions already recorded in 2022, when reservoir levels were already significantly reduced by the start of summer”. Despite this situation, Edison, together with Enel and A2A – the concessionaires of the dams upstream of Lake Como – in agreement with the Lombardy Region, on 30 June decided to release 4 million cubic metres of water per day into the lake for 15 days, with the aim of meeting the irrigation needs of agriculture in the Adda river basin.
