A GIANT sand slug is slowly choking the narrowest section of the Murray River and could seriously impact water delivery within the next decade or even alter its course.
The Murray Darling Basin Authority is exploring six options to deal with slow moving mass plaguing the Barmah Choke.
Independent experts have been 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.
Since the 1980s, the capacity of the Barmah Choke has reduced from 11,300 megalitres a day to 9200ML per day.
MDBA River Murray operations director Tyson Milne said the sand slug 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."
Studies show the sand is continuing to move downstream into national parks, increasing erosion, damaging culturally significant sites and access to recreational areas.
The build-up of sand is also increasing the risk of the Murray River changing its course.
"We cannot afford to do nothing because the problem is getting worse," Mr Milne said.
"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."
After 12 months of community consultations, the MDBA has put forward six options for basin governments to consider at their next Ministerial Council meeting.
Among the options being explored are a five-year project to stabilise banks, selective removing the sand from key locations, making changes to the time of water transfers to Lake Victoria and assessing the potential to transfer Snowy releases to the Murrumbidgee for delivery into the Murray River.
MDBA has also suggested using the existing infrastructure of the region's large irrigators to relieve pressure on the Barmah Choke.
A preliminary scoping report will be published by the end of July, with a business case due in late September, and final report in December.