Goulburn and Loddon seasonal determinations reach 100 per cent of high-reliability water shares

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

The Goulburn and Loddon systems increase from 85 per cent high-reliability water shares (HRWS) to 100  per cent HRWS.

The Murray system moves from 77 per cent of high-reliability water shares (HRWS) to 93 per cent HRWS.

The Broken system rises from 100 per cent HRWS and 41 per cent of low-reliability water shares (LRWS) to 100 per cent HRWS and 85 per cent LRWS. The Campaspe system remains at 100 per cent HRWS.

Seasonal determinations in the Bullarook system stay at 100 per cent HRWS and 100 per cent LRWS.

Resource Manager Mark Bailey said recent rainfall drove the increased water availability.

“The rain on wet catchments added significant volumes to the storages,” Dr Bailey said.

“With tributaries downstream of the storages meeting demand, more water was available for the seasonal determinations.”

Dr Bailey also confirmed the first deductions from Murray spillable water accounts this season.

“A deduction of 89 gigalitres will be made with today’s announcement,” Dr Bailey said.

“This is about 31 per cent of the current volume held in the spillable accounts.

“The Murray-Darling Basin Authority is releasing water to manage Lake Hume close to the full supply level. The releases to date have exhausted the rules-based accounts in the Murray system and spilled at least 89 gigalitres from Victoria’s share of Lake Hume.

“As releases to manage the Lake Hume volume continue, Murray system entitlement holders should expect further deductions from spillable water accounts in the next seasonal determination update.”

The latest Bureau of Meteorology seasonal outlook favours above-average rainfall across the northern Victoria for the October to December period. The Bureau has issued a La Niña watch, meaning the chance of a La Niña event forming is around 50 per cent. The negative Indian Ocean Dipole is nearing its end, but may still influence rainfall over the coming months. A negative Indian Ocean Dipole and a La Niña each increase the likelihood of above-average rainfall totals in south-east Australia.

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 about 10 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 40 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  Victorian Water Register website.

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  Victorian 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 Monday 11 October 2021.
• The next 2021/22 seasonal determination announcement will be released on Friday 15 October 2021.