July 1977: 108 ha of Old Mill Stream catchment sprayed with 1.12kg a.i. butyl ester of 2,4,5-T in 48.6 litres of distillate (120kg used on the target area). Stream immediately below the sprayed area was sampled twice daily for 5 days before spraying and at 12 minute intervals for a period of 13 days during and following spraying. 2,4,5-T was detected in samples on 7th and 8th day following spraying, during a period of heavy rain. On the 7th day the maximal concentration was 10ug/l with all other values of 4.3ug/l or less. 8th day concentration was 1.0ug/l . . . 2,4,5-T could not be detected (ie less than 0.3 ug/l) in samples collected 2.5 km downstream of the spray area at any time during the period of study (see 2,4,5-T Residues in Stream Water Following Aerial Spraying for Woody Weed Control in the Narbethong Plantation by RJ McKimm & P Hopman Research Branch Report No 112. June 1978 Forest Commission).