00:02It's long been a lifeline for farmers in southern Tasmania.
00:06Now, there are plans to pump more than 14,000 Olympic swimming pools of water from the River
00:13Derwent to irrigate farms in one of the state's driest areas.
00:18That plan alarms Christine Kochenauer, one of Tasmania's most prominent water scientists
00:24and the founder of the Derwent Estuary Program.
00:26I was really shocked that given what I'd always been told that, you know, the Derwent flows
00:32in summer were very low, that we were contemplating taking another, you know, 37,000 megalitres.
00:40The Greater South East Irrigation Scheme will supply water from the Derwent's Lake Meadowbank
00:45to areas north and east of Hobart from 2030.
00:49But Ms Kochenauer says there's been no studies investigating the impact of further summer
00:55water extraction from the area for 24 years, and the last study cautioned against it.
01:02In 2002, the state's Environment Department commissioned scientists to investigate environmental flows
01:08in the Lower Derwent River.
01:10They recommended against allowing any additional water extraction over summer, finding that would
01:16risk further decline of environmental values.
01:19We don't have more recent research, so you start with what you've got, which was very
01:24high quality at the time.
01:26And if you're not happy with that, redo that research and come up with a better plan.
01:33Tasmania's Natural Resources and Environment Department says water releases from Lake Meadowbank
01:39will ensure a flow regime at all times, intended to protect river health.
01:45Tasmanian Irrigation says further studies are planned to develop new modelling on river flows.
01:51We'll be doing a range of environmental studies for this project in consultation with the state and federal regulators
01:57to determine the impacts of the project.
02:01The scheme has secured substantial taxpayer funding, $150 million from the federal government
02:08and $75 million from the state.
02:11I have every confidence that we can get the natural resource management science right.
02:17I'm very confident that this scheme is the right scheme for southern Tasmania.
02:23But Ms Kokenauer says taxpayers deserve more assurances.
02:27The Derwin is already stressed.
02:30In summer we have low oxygen levels, we've had a history of algal blooms, we've had fish
02:35kills, and the risk of lower flows would exacerbate all of those things.
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