Seasonal Determination – 1 September 2021

Wednesday 1 September, 2021

The Resource Manager for northern Victoria today updated the 2021/22 seasonal determinations.

The Murray system moves from 52 per cent of high-reliability water shares (HRWS) to 57 per cent HRWS. The Goulburn and Loddon systems increase from 66 per cent HRWS to 71 per cent HRWS.

The Campaspe system moves from 87 per cent HRWS to 97 per cent HRWS. The Broken system increases from 68 per cent HRWS to 81 per cent HRWS.

Seasonal determinations in the Bullarook system remain unchanged at 100 per cent HRWS and 100 per cent of low-reliability water shares.

Resource Manager Mark Bailey said streamflows across the catchments remain solid despite the lower rainfall during August.

“Tributary flows are supplying the demand that is emerging with the warmer and drier weather,” said Dr Bailey. “Meeting demand without releasing water from storages allows for increased allocation to entitlements.”

Dr Bailey noted the Murray system is repaying water borrowed from the Barmah-Millewa Forest Environmental Water Allocation at the start of 2021/22. “The repayment started when the Murray seasonal determination reached 50 per cent HRWS and will continue until the system reaches 100 per cent HRWS.”

“Around 58 GL of the 350 GL borrowed to underwrite Murray seasonal determinations has been repaid.

“Also in the Murray system, the Murray-Darling Basin Authority stopped pre-releases from Lake Hume in mid-August as flows receded. This action should not affect spillable water accounts at this point, but pre‑releases may resume if wetter conditions return.

“About 150 GL needs to be pre-released or physically spilled from Victoria’s share of Hume before spillable water accounts are affected.”

The latest Bureau of Meteorology seasonal outlook continues to favour above-average rainfall across the northern Victoria for the three month period from September to November. The negative Indian Ocean Dipole continues, which increases the likelihood of above-average rainfall totals in south-east Australia.

The seasonal determinations for northern Victorian water systems on Wednesday, September 1 are 

Water System

High-Reliability Water Share

Low-Reliability Water Share




















Trading Opportunities

Allocation trade from New South Wales to Victoria is limited to the lesser of a net annual volume of 200 GL or a volume that keeps the risk of spill in the Victoria’s share of both Hume and Dartmouth reservoirs below 50 per cent. While the risk of spill at Lake Hume is effectively 100 per cent, the risk of spill at Dartmouth is less than 5 per cent and this is where trade adjustments will occur.

The current risk of spill in the Murray system allows 200 GL of net trade from New South Wales to Victoria as this would increase the risk at Dartmouth to about 15 per cent. This volume will be updated with each risk of spill announcement. Customers can find out more about trade opportunities and a trial of improved trade adjustment methods on the Victorian Water Register website

An interim rule for trade from the Goulburn, Broken, Campaspe and Loddon systems to the Victorian Murray system, New South Wales and South Australia is in effect from 1 July 2021 to 30 June 2022, replacing the previous rule that had been in place since 2013. The new trade rule means that until December 15, 2021, trade is allowed whenever the total amount owed from the Goulburn to the Murray, including the Lower Broken Creek, is less than 190 GL. From December 15, 2021, net trade will be capped and the inter-valley trade account balance will be run down.

The volume currently committed to the Murray is 190 GL, meaning trade from the Goulburn, Broken, Campaspe and Loddon systems to the Victorian Murray system, New South Wales and South Australia is closed. More details about the new trade rule are available at

The Goulburn, Campaspe and Loddon systems can trade from the Victorian Murray system, New South Wales and South Australia while the total volume owed to the Murray system is greater than zero.

Customers participating in the water trading market can monitor trade availability on the Water Register website,

The Murray-Darling Basin Authority (MDBA) is restricting trade of water allocations from above the Barmah Choke to downstream of the Choke to protect the delivery of downstream water entitlements. Customers can monitor trading opportunities across the Barmah Choke on the MDBA website

Upcoming Resource Manager Announcements

  • The next risk of spill update will be released on Friday September 10, 2021.
  • The next 2021/22 seasonal determination announcement will be released on Wednesday September 15, 2021.