1973 June: Forests Commission, Clear Creek: 2,4,5-T Experiment

“In June 1973 the F.C.V. (Forests Commission Victoria) carried out a larger study in 1 335 hectare section of a pine plantation in a catchment of Clear Creek near Myrtleford. Four stream sample points were established at varying distances from the spray area and a total of 1,000 samples were collected over a ten day period. Major peaks in 2,4,5-T concentration occurred after rain, and lesser, relatively insignificant, peaks also occurred during spraying (McKimm, 1974). McKimm stated that 2,4,5-T concentrations were in excess of the upper limit of 20 ug/litre set by the N.H. & M.R.C. but he did not list values. In fact, at the sampling point immediately below the spray zone values of 75 ug/l were obtained during spraying and peaks up to 690ug/l were obtained after rain. Three kilometres downstream values of 135 ug/l were obtained during spraying and peaks up to 500ug/l were obtained after rain. Worse, for the sampling point immediately below the spray zone, of 83 readings made during the seven days after spraying, 48% (40) exceeded 20 ug/l.; 14% (12) exceeded 50 ug/l.; and 7% (6) exceeded 100 ug/l. These measurements indicated that there was a significant threat to streams in aerially sprayed areas, but nothing was done. Rather, two new monitoring programs were organised, one at Carboor near Myrtleford and another at Narbethong in the Central Highlands.” (Source: The Herbicide 2,4,5-T and its use in Forestry. By Peter Rawlinson Zoology Department, LaTrobe University, Bundoora, 3083. 1980?)