International Mine Water Association
Faculty of Computing, Health and Science
School of Natural Sciences / Centre for Ecosystem Management
Breach and subsequent decant of an acidic brackish pit lake in the Collie Coal region in south-western Australia occurred during flooding of a pre-mining diverted eutrophic river. Inflowing fresher river water with high alkalinity and nutrient concentrations settled over more saline and acidic pit lake water. This created a halocline with better mixoliminion water quality and monimolimnion water quality typical of the pre-breach lake. Flow-through may represent the best long-term mine closure option for this and other pit lakes in the state and internationally where pit lake water quality degrades over time when excised from regional water systems.