1994 April: Spill of the insecticide pyrethum at Tonganah, near Scottsdale Tasmania. Killed massive numbers of fish, eels and freshwater crayfish. 3 years after the spill river health better but a lack of blackfish and freshwater crayfish a concern (Mercury 5/7/97).

http://hancockwatch.nfshost.com/docs/historylesson2.htm