Acid drainage water

A project is under way examining the nature of acid drainage originating from the Lower Murray, in an area known as the Lower Murray Reclaimed Irrigation Area (LMRIA).

Staff from the Department of Environment, Water and Natural Resources, the Murray-Darling Basin Authority and the Environment Protection Authority (EPA) are monitoring and researching acid drainage to better understand the risks associated with it. 

Acid drainage happens when naturally occurring acid sulfate soils in the riverbed are exposed to air and oxidise, forming sulfuric acid (the same acid as in a car battery) and exposing natural metals such as manganese and aluminium. This occurred below Lock 1 in the drought of 2006-10, when river levels dropped to unprecedented lows.

When water levels returned to normal, acid and exposed metals washed out of the soils into drainage channels. Acidic water (less than pH 4) is then released into the River Murray system through normal agricultural practice.

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