About 220 years ago, as recorded by the oral history of the Nisga'a people, the Nass River was dammed by a long lava flow which came from the Tseax Cone and destroyed the Nisga'a villages and caused the death of at least 2000 Nisga'a people by volcanic gas and poisonous smoke. The volcano has been active on at least two occasions (220 and 650 years ago) in the last millennium. Because of our knowledge of this previous disaster, modern monitoring techniques should include studies of the gases emitted by the volcanoes and the institution of a warning system to alert people living down slope from the volcanoes.