A Colac district resident says that if Barwon Water pumped water from the Barwon Downs borefield again it could “dry up the whole of the Otways”.
Water campaigner Malcolm Gardiner said he was concerned about the effect that groundwater pumping would have on Colac district waterways if it was pumped again.
Barwon Water’s managing director Joe Adamski said the Barwon Downs borefield was a back-up water source for Geelong, as well as the Geelong Melbourne pipeline “in the event that extreme dry water conditions continued”.
Barwon Water defined extreme dry conditions as “a sustained period of below average rainfall and inflows”.
But Mr Adamski said there was “no single pre-determined storage level at which the supplementary sources would be turned on”.
Mr Gardiner said he opposed Barwon Water’s plan to pump the borefield and that it was an “unsustainable” approach to obtain water.
“They should not be pumping water until the aquifer fully recharges,” he said.
Mr Gardiner campaigned against Barwon Water’s decision to boost Geelong’s water supply with ground water because of the impact on Colac district waterways.
He said last time Barwon Water pumped the borefield the drop in groundwater levels caused “one of the top three actual acid sulphate soil sites in Australia”.
Mr Gardiner’s concerns were supported by Southern Cross University reports into inland acid sulphate soils in 2012 which measured the Otways toxicity levels at 16 per cent.
The Commonwealth Scientific and Industrial Research Organisation said that when acid sulphate soils were drained or excavated, the sulphides react with oxygen in the air and forms sulphuric acid.
The CSIRO reports acid, together with associated toxic elements, can kill plants and animals, contaminate drinking water and corrode concrete and steel.
Mr Gardiner said actual acid sulfate “just kills everything”.
He said groundwater pumping caused surface water to dry up which created “longer, drier summers”.
“Summers, they come in earlier and last longer because the surface is dryer than it normally is,” Mr Gardiner said.
He said he was concerned for farmers and the lack of water available to them due to groundwater pumping drying up surface water.
Mr Adamski said “unlike the 2006-2010 drought, during which the borefield provided up to 70 per cent of Geelong’s drinking water, the addition of the Melbourne to Geelong pipeline as a supply source would mean less reliance on Barwon Downs”.