The Northern Territory government was warned that increasing water allocations for industry could change the flow to a major Top End river.
Conservationists say a confidential government memorandum, released under freedom of information laws to the Environment Centre NT, should prompt the territory government to be cautious as it drafts water allocation plans for the Beetaloo Basin.
The document, written by the then director of water planning, Tim Bond, in 2020 warned applying water allocation rules used in the southern arid zone to an aquifer farther north, could eventually cause some water flows to the Roper River to move in the opposite direction.
Kirsty Howey, the co-director of the Environment Centre NT, described the memorandum as “shocking”, saying it pointed to potentially “catastrophic impacts on iconic territory waterways” including the Roper River and the Mataranka hot springs.
In the Northern Territory, water is managed through water licences and water allocation plans.
Water allocation plans are a way of strategically planning for long-term water use, including water for the environment and communities, and sustainable consumption of water by industry.
If a region has no allocation plan in place, there are contingent rules that divide the territory into two zones: the top end and the arid zone.
Under the top end rules, 20% of an aquifer’s annual recharge from rainfall can be granted for consumption by industry including agriculture and fracking.
In the arid zone, 80% of an aquifer’s storage is available for extraction by industry over the course of 100 years.
In the arid zone, far more water is available for annual extraction than can occur under the top end rules and conservationists have raised concern the government has begun applying these rules to licences in the northern zone.
In 2020, the government was considering an application from the Northern Territory Land Corporation to extract 12,500 megalitres of groundwater from the Mataranka Tindall Limestone Aquifer near the town of Larrimah, within the top end zone.
In written advice, Bond considered what could occur if arid zone rules were applied to allow industry to draw down 80% of the aquifer’s storage over 100 years. He wrote such an approach “will not provide for the environmental and cultural water requirements supported by the aquifer”.
He wrote that lowering the upper surface height of the aquifer could reverse its gradient which would remove “through flow to areas near the southern side of the Roper River and cause water to flow in the opposite direction towards Larrimah”.
The territory government ultimately issued a licence for 10,000ML – more than would have been permissible under the more cautionary top end zone rules – a decision Howey said “beggars belief”.
The decision was overturned after the Environment Centre NT sought a review last year.
The government will soon release proposed water allocation plans that will guide water management for new gas projects in the Beetaloo Basin.
Part of the Beetaloo falls within the top end zone.
“It’s crucial that there is a transparency, accountability and a precautionary approach taken with these plans,” Howey said.
“This approach must accord with the science and not permit water mining, which is what the arid zone facilitates.”
Sue Jackson, a professor at the Australian Rivers Institute at Griffith University, said she hoped the territory government would present a “scientifically defensible rationale” for estimating the amount of water that could be sustainably extracted.
She said this should be based on a principle that industry “should not take more water out of aquifers than is being replenished”.
“Once you’ve over-allocated, it’s very difficult to claw back those entitlements,” she said.
A spokesperson for the NT Department of Environment, Parks and Water Security, said the advice in the memo was “the view of one staff member” and it was not shared by other officials in the water assessment branch.
They said the memo was not persuasive to the decision-maker who issued the licence that was later overturned and the document had been “superseded” by another technical report, co-authored by Bond.
The spokesperson said the NT government had not changed the rules that govern water allocation in the territory. It had, however, “better defined the delineation of what is considered either an arid or top end aquifer or waterway based on characteristics, geography and rainfall and recharge”.
The spokesperson said the process to set sustainable water yields in the forthcoming water allocation plans would consider “the water requirements of key environmental values and protections to flows”.
They said there were no water allocation plans currently in effect in the territory that allowed storage depletion of 80%.
The draft plans are expected to be released for public consultation in October.
