The guelh de Joèu, also spelled güell de Joeu (Catalan), Uell or uelh de Joeu , or from Jouèou, goell del Jueu, guelh deth Jueu, depending on the different languages u200bu200b(Castilian, Catalan, Aranese) and spellings used, found in Val d'Aran, in the Artiga de Lin valley (Spanish Pyrenees), at an altitude of 1,658 m. It is a resurgence of water from the Maladeta massif in Aragon, which rushes into the karstic abyss of Forau de Aigualluts or Trou du Toro, and which constitutes the main source of the Garonne, as demonstrated in 1931 by speleologist Norbert Casteret. The stream born from this resurgence, the Joèu or Joueou (Et Juèu in Aranese), joins the Garonne, of which it is in fact the main course according to conventions, being from the highest altitude (massif de la Maladeta), even if its flow and its length are much lower than those of the Garonne born in Pla de Beret, which is still considered as an "official" source by the Aranese and Spaniards.