Planning for the next drought in the Murray Darling Basin should not be handicapped by arcane, arbitrary rules which do not allow for adaptive management.
The Shadow Minister for Water, Senator Perin Davey said rules in the Murray Darling Basin Agreement, which predates the Basin Plan and has not been reviewed since the 1980s, could have perverse outcomes in an Australia facing more extreme weather events.
“For example, the Additional Dilution Flow rules will see significant volumes of water released from Menindee just as we are moving into an El Nino hotter, drier weather pattern and potential return to drought,” Senator Davey said.
“Releasing thousands of megalitres of water from Menindee Lakes for an arbitrary rule which predates the Basin Plan to deal with a problem which doesn’t exist right now does not make sense.
“It is no point wishing in the middle of the next drought that we still had water left in the Menindee Lakes to keep the Lower Darling flowing so we don’t see a repeat of the 2019 fish deaths and water is available for critical human needs, the environment and stock and domestic supplies,” she said.
Senator Davey explained the rule is triggered when there is more than 2,000,000 megalitres in Hume and Dartmouth Dams and a storage target is met in the Menindee Lakes varying depending on the month.
Originally designed to address salinity, when triggers are met, an additional 3,000 megalitres a day is required at the South Australian border irrespective of water quality, salinity or whether there has just been a major flood. As the rule currently stands, the additional water usually comes from the Menindee Lakes.
“Menindee Lakes and the Lower Darling were disconnected from the Murray during the Millennium drought and again during the record low inflows in the Northern Basin between 2017-2019, during both events locals had warned that releasing water from the lakes too fast would have devastating effects,” Senator Davey said.
“We have now gone from the extreme record-breaking drought to the other extreme of record-breaking floods that saw Menindee Lakes fill and spill and almost 30 million megalitres of water flow over the South Australian border since July 2021, well over the usual annual regulated flow of 1.85 million megalitres.
“We must learn from this sequence of extreme weather events and draining Menindee Lakes so soon after one of the biggest flooding events in our lifetime to deal with an issue that isn’t a problem and is not smart way to manage our precious water resources.
“NSW brought in new rules to protect the small to medium flows coming into the Menindee Lakes in dry times but nothing has changed in relation to how fast and when the Menindee Lakes are drained which is just as important for our river system.
“We need to save the water which would be drained from the Menindee Lakes in coming months to be used in the next drought to maintain connectivity in the Lower Darling and help ensure we don’t see a repeat of the fish deaths we saw in 2019,” Senator Davey said.