Mining of gold and copper at Mt Morgan in Central Queensland has a long history and has resulted in acid mine discharge (AMD) entering the Dee River. The Queensland Government Department of Minerals and Energy began a major investigation of the AMD associated with the river in 1994 to determine the sources of the pollution and its effects. Studies of the sources of the pollution are currently being undertaken by C.S.I.R.O. and the first of the two of these is titled "Sources of contamination of the River Dee by past and present discharge from the Mt Morgan mining leases under low flow conditions". The second deals with the same topic but under moderate flow conditions. The present study deals with the effects of the pollution on the biota of the river. The information contained herein will provide a basis for decisions pertaining to water quality management in relation to the Mt Morgan mine site. The study is divided into three parts, corresponding to the following three aims: 1) To provide a review of the ecological impact of AMD on the Dee River; 2) To develop a procedure for detecting long term trends in the river's ecology as water quality changes, improves or declines and 3) To determine the current biological status of the river in relation to AMD