Water

2020-21 water year looks positive, according to MDBA operating report

By Rodney Woods

The outlook for 2020-21 is looking more positive compared to last year, according to the Murray-Darling Basin Authority's Annual Operating Outlook.

Each year the MDBA releases an Annual Operating Outlook that explains how the MDBA may operate the Murray River system across a range of possible climate and rainfall scenarios to assist water users and river managers with planning ahead.

MDBA river management executive director Andrew Reynolds said the full range of scenarios from extreme dry to very wet had been considered, but river managers were cautiously optimistic that 2020-21 would be a better year than 2019-20.

“The outlook is better than the same time last year because we've got the trifecta we've been waiting for — catchments are primed after the wet autumn, we've got more water in storage compared to the same time last year and the Bureau of Meteorology is forecasting higher than average spring rainfall,” Mr Reynolds said.

As of July 22, southern basin storages were at 51 per cent compared to 40 per cent 12 months ago.

“We're still a way off filling the storages, but the critical mid-Murray storage at Lake Victoria is close to capacity, thanks to good winter flows from the tributaries downstream of Hume Dam,” Mr Reynolds said.

“This means less of the supply to South Australia will need to come from the Hume as it’s sitting there in Lake Victoria now, ready to go.

“While we hope for good rain, as river managers we need to plan for a range of conditions — nobody knows for sure what the weather will bring.

“If conditions revert to a drier scenario, we need to be ready for it, so we continue to operate the system as effectively and efficiently as possible.

“The river is a dynamic environment so planning ahead helps river operators to identify and manage risks to river operations and water supply.

“That includes the ongoing risk of a delivery shortfall, where demand outstrips our ability to move water through the system.”

This year the outlook considers the shortfall risk to be greatest in late summer and autumn under ‘moderate’ or ‘near-average’ rainfall scenarios, due to the Barmah Choke, inter-valley trade constraints and other limitations on the system's capacity to meet the anticipated demand for water.

The 2020-21 MDBA Annual Operating Outlook is available at: www.mdba.gov.au/publications/mdba-reports/river-murray-system-annual-operating-plan