The massive sand slug in the Barmah-Millewa Reach of the Murray River will end up choking the ability to deliver water downstream, an expert has told a major conference on our rivers.
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The Barmah Choke is the narrowest section of the river that runs through the Barmah-Millewa Forest near Echuca and Deniliquin.
Capacity through the Barmah-Millewa Reach has reduced from 11,300 ML/day in the 1980s to 9200 ML per day today.
Independent experts in fluvial geomorphology, stream management and river research have been gradually surveying the riverbed over the past 18 months and estimate 20 million cubic metres of sand is on the riverbed between Yarrawonga and Picnic Point.
Murray-Darling Basin Authority director of River Murray operations Tyson Milne told delegates it’s understood the sand was largely caused by land-use practices and mining in the rivers upstream centuries ago.
“We are talking about 13 Melbourne Cricket Grounds full of sand, which is quite phenomenal,” Mr Milne said.
“There is no silver bullet to this complex problem and the ecological, cultural, economic and community implications of any course of action are being considered.”
Mr Milne said doing nothing wasn’t an option because the build-up of sand was getting worse.
Studies show the sand is continuing to move downstream, and into the RAMSAR-listed national parks, increasing erosion and impacting cultural sites and access to recreational areas. The build-up of sand is also increasing the risk of the Murray River changing its course.
“Within 10 years, the build-up of sand in the Barmah-Millewa Reach will have a major impact on our ability to deliver water downstream,” Mr Milne said.
“Over the past 12 months we have been talking with the community, First Nations groups, irrigators, government and councils to get their perspectives and input on how this problem could be addressed.”
The six options being explored are:
a 5-year project to stabilise banks and reduce degradation to prevent further losses into the Barmah-Millewa Forest;
selectively removing the sand from key locations where riverbank erosion is accelerating, causing environmental and cultural loss;
making changes to timings of water transfers to Lake Victoria (Tar-Ru);
using Goulburn Murray Irrigation District’s existing and new infrastructure to relieve pressure on the Barmah-Millewa Reach;
using Murray Irrigation Limited system to deliver water to natural ephemeral creeks of the Edward/Kolety – Wakool – Niemur river system; and
assessing the potential to transfer Snowy releases to the Murrumbidgee for delivery to the Murray River.
A preliminary scoping report will be published by July 30, with a business case due in late September and final report in December.
The options will be considered by water ministers at their next Ministerial Council meeting.