The amount of water allowed to be taken from complex underground systems across the Murray-Darling is set to be dramatically increased under new plans for the basin.
The independent Murray-Darling Basin Authority, which is drawing up draft plans to reform use of the river’s water, is now considering increasing limits on water extracted from aquifers by an extra 2400 billion litres a year basin wide.
But details of the authority’s ”current thinking” - obtained by green groups - would lift limits for groundwater extraction to about 4200 billion litres a year across the entire basin.
Groundwater systems are treated differently to surface water such as rivers and wetlands.
The authority has flagged a proposed cut of 2800 billion litres to surface water extraction by farmers and rural communities every year in the draft basin plan, due to be released next month. Water from many aquifers is often saline and not suitable for irrigation, and instead used for stock and domestic purposes or mining needs including coal-seam gas.
Under a ”guide” document to the new basin plan released last year, the authority floated a basin-wide limit of 2095 billion litres a year for groundwater when water previously assigned was factored in.
The authority now says the dramatic increase between last year’s guide proposals and its current thinking is the result of extra information on groundwater systems, including data provided by state governments.
It says the higher proposals would still be well below the rate of how quickly water ”recharged” in the underground systems. Authority chairman Craig Knowles said ”in assessing the amount of water that is available for extraction [by the state] we have assessed each aquifer according to the risk to recharge and we have looked at making only a proportion of that recharge available for use”.
”There are some areas where we believe more can be accessed but we are still making less than 50 per cent of the recharge available,” he said.
”When you consider across the basin, the proposed total groundwater extraction volume is approximately 0.1 per cent of the total groundwater resource.”
Water Minister Tony Burke said: ”My bottom line is that levels of extraction for both groundwater and surface water in the Murray-Darling must be sustainable.”
While the authority is proposing large increases to the amount of water allowed to be taken from most Murray-Darling groundwater systems, including nine in Victoria, some aquifers could see small reductions or stay at current limits.
Murray-Darling campaigner for Friends of the Earth Jonathan La Nauze said: ”This proposal undermines the intent of the basin plan which is supposed to be about reducing pressure on water resources, not increasing it. This would allow a vastly expanded mining industry to bring trillions of litres of salty water to the surface, doing untold damage to biodiversity, rivers and prime agricultural land.”
Mr Knowles said the authority was only responsible for setting limits and not in control of how the water was used, which are decisions for states.
Research by the CSIRO in 2008 found that a number of groundwater systems with good quality water had been developed to or above their maximum, but there were areas of less extraction indicating development potential.
