The Hers-Mort (the "Dead Hers", as opposed to the faster-flowing Hers-Vif, or "Live Hers") is a 90-kilometre (56 mi) long river in southern France, a right-bank tributary of the Garonne. Its average flow rate is 4 cubic metres per second (140 cu ft/s). The Hers-Mort rises in the Lauragais region, near the village Fonters-du-Razès, in the Aude department.