Desalination plant impact overstated, finds report

A new report by the University of New South Wales has found that the highly saline flows from the Sydney Desalination Plant does not impact on marine life as much as was commonly thought.

The six-year study on the Sydney Desalination Plant looked at the effects on marine invertebrate recruitment of pumping and ‘diffusing’ of high concentration salt water back into the ocean.

The UNSW Sydney-led research is being published at a time of increasing reliance on desalination plants for drinking water across most states in Australia, as drought conditions in the east and south worsen and domestic water supplies decline for both metropolitan and regional areas.

UNSW Dean of Science and senior author of the study, Professor Emma Johnston, said the results are timely as they coincide with renewed focus on desalination, with the plants in Sydney and Melbourne preparing to start operations due to rapidly decreasing water supplies.

“Increasingly, frequent and severe climate and population driven water shortages are projected to accelerate the growth in desalination in the coming years,” Professor Johnston said. “The good news is that our comprehensive study shows the hyper-saline outflow from this modern plant is not having a major impact on the NSW coast.

“We do need reliable and high-quality drinking water and we need to understand the potential for ecological damage from the act of extracting it from the ocean. There is a real possibility that the Sydney desalination plant could be expanded to meet demand if storage gets critical, with the original design having the potential for a doubling of its size in the future should the need arise.”

The logistically challenging study took place at six underwater locations, at a depth of about 25 metres, over a six-year period during which the plant was under construction, then operating and then idle. This enabled the team to rigorously monitor for impacts and recovery among marine life from the effects of pumping large volumes of hyper-saline water into the ocean.

Professor Johnston stressed the study results do not mean the urgent need for more sustainable water use can be ignored: “Water saving and water re-use practices should be the first strategies considered by any state. Our study simply shows that the potential marine ecology impacts from a well-designed, and well-located desalination plant should not immediately prevent us from considering desalination for the supply of fresh drinking water in a period of severe, prolonged drought.”

The full report can be found here

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