Gat mortGat mort is a left tributary of the Garonne, in southwest France. It is long.GeographyGat mort rises in the Landes de Gascogne Regional Natural Park, in the commune of Hostens, generally drains in a north-easterly direction through the Graves wine-growing region and flows into the Garonne as a left tributary after about at the municipal boundary of Beautiran and Castres-Gironde.Department and townsGat mort flows through the following department and towns:Gironde : Hostens, Saint-Magne, Louchats, Cabanac-et-Villagrains, Saint-Morillon, Saint-Selve, Castres-Gironde, Beautiran.