The Durance was once feared for its floods and deemed impassable because of its high flow and significant width. The river was even considered one of the three plagues of Provence, along with the mistral and the parliament of Aix-en-Provence. The dam built in 1961 at Serre-Ponçon made it possible to regularize the course of the Durance and to constitute an immense reservoir for the irrigation of its valley for the greatest benefit of agriculture. Today, the Durance's level variations maintain a diversity of natural habitats made of gravelly, sandy, or silty iscles in perpetual motion.