Drought scenarios are more and more frequent. The river beds are dry. Only a few oases of life resist. They are fed by resurgences and protected by mud. Fish from across the river congregate in silted pools of water. They take shelter in the shade of the mud, breathe the oxygen produced by the mud and feed on aquatic invertebrates that graze on the mud. The mud absorbs household pollutants, nitrates, phosphates from fertilizers spilled by agricultural activities. It cleans the water column. Sticky, fibrous and hated by human beings, it protects a small people who resist every summer to increasingly severe droughts.