[en] An investigation of the issues raised by a former employee of Energy Resources of Australia Limited (ERA) at Ranger Uranium Mine's Environmental Laboratory about a number of issues relating to environmental management and reporting by ERA at the Ranger mine between 1996 and 1998, has been carried out. The investigation was undertaken jointly by the staff of the Supervising Scientist Division (SSD) and of the Northern Territory Department of Business, Industry and Resource Development (NTDBIRD). A detailed search of files and reports held by SSD, Energy Resources of Australia (ERA) and NTDBIRD was conducted to establish, as far as is now possible, the circumstances surrounding the events referred to the former employee. Field visits were also conducted to determine the current situation at the relevant sites and discussions were held with current ERA staff. In addition, interviews were conducted with a number of former staff of ERA and with one former Office of Supervising Scientists employee to determine their recollections and account of events. The compliant was also interviewed to allow him to present further information and to clarify information presented in his report. The overall conclusion of this report is that, apart from the previously reported breach of the Ranger Authorisation arising from the spillage of tailings outside the Restricted Release Zone on 19 December 1997, no evidence has been found that ERA has operated otherwise than in accordance with its Authorisation and the Commonwealth's Environmental Requirements. The report recommends that the Ranger Minesite Technical Committee, should, in its current review of the Ranger monitoring program, assess the need for load estimation in the chemical monitoring of the Ranger mine, taking into account existing biological monitoring programs and consider, within the context of Best Practicable Technology, whether or not uncontrolled discharges of water from the region south of the tailings dam to the Gulungul Creek system should continue