October 1989: 121.3 ha sprayed with 485.2kg of Velpar ULW. ‘The highest levels of hexazinone detected in streamwater were at the Neerim East site, these being 18.0ug/l, five days after application and 17.5ug/l one month later following the largest rainfall measured . Monitoring was undertaken 2 to 3 km downstream of the treated areas detected trace residues of hexazinone in only three of the 24 samples analysed, the maximum concentration being 1.3ug/L.
Source: (Weed Control in Radiata Pine plantation by aerial application of granulated hexazinone – Lands and Forests Technical Report No. 5 Conservation and Environment 1991).