“There is still water, you see! » The sentence launched by Christophe Mirmand is intended as a joke, while behind him sparkles the immense turquoise expanse of Serre-Ponçon, the largest artificial lake in France. However, the humor of the prefect of the Provence-Alpes-Côte d’Azur region struggles to hide the crisis situation that this jewel of the Alps is going through, located on the border of the Hautes-Alpes and the Alpes-de-Haute- Provence. Faced with an extreme drought, the reservoir sees its level drop day after day. On Saturday July 30, the latter reached thirteen meters less than the optimum filling level. Tourist activities are trying somehow to adapt, against a backdrop of tensions around a resource that is becoming scarce.
A boat trip allows you to take the measure of an exceptional situation for the season, close to the 1990 record. Upstream, near Embrun, the “tail of the lake”, as it is nicknamed, is no more than a vast plateau of sediments, swept by a scorching wind, within which winds a skinny Durance. Going downstream, the streaks on the banks like the marks on the piers of the Savines bridge betray the drop in the water level. On the banks, pontoons lie on the stony ground instead of floating.
In normal times, this immense reservoir, of 1.2 billion cubic meters of water, is filled thanks to the contributions of the Durance and the Ubaye. But this year, the lowest precipitation, snow and then rain, has resulted in a record minimum flow of these two rivers. Result: the lake is only 72% full.
“We can’t swim here anymore”
The blow was severe for the tourist activity. Three of the eight beaches are prohibited for swimming, two service stations for boats are no longer passable and nearly 500 boats can no longer park on the 760 places managed by the Joint Syndicate for the Development of Lake Serre-Ponçon (Smadesep) . “We were taken aback, recognizes Victor Bérenguel, the president of Smadesep and also mayor of Savines-le-Lac. Such a low water level is a problem in this season as long as the lake is not suitable. »
The lake was created in 1959, at the time of the construction of a dam on the impetuous Durance, with three missions: to produce electricity, to irrigate Provence and to fight against floods. The stakes of tourism were not integrated until later, by an agreement signed in 2008 between Smadesep and EDF. In winter, the lake can be pumped for energy needs. And in summer, EDF undertakes not to lower the water level by more than 5 meters below the normal level of the lake, which is 780 meters (altitude in relation to sea level). Today, the equipment can thus withstand a water level of 775 meters… but not the 767 meters reached at the end of the month.
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