Low-reliability water still elusive

Allocation planning: Lake Eildon is currently holding about 87 per cent of its capacity, an eight-year high. Photo by darren linton

Despite improved storage levels in major reservoirs and the promise of more rain to come, the prospect of northern Victoria irrigators receiving a low-reliability water allocation in the biggest districts is still some way off.

According to Goulburn-Murray Water, more reserves are needed before an allocation of low-reliability water can be made.

In the latest G-MW annual water outlook, the authority notes the seasonal determinations are at 100 per cent of high-reliability water shares (HRWS) in all G-MW systems, with the Broken and Bullarook systems also having 100 per cent of low-reliability water shares (LRWS).

G-MW expects the strong resource position to continue over summer, with the Bureau of Meteorology recently determining there was a 55 to 70 per cent chance of above median rainfall across the G-MW region from December 2021 to February 2022.

However, resource improvements for the remainder of 2021-22 will first go towards establishing reserves for 2022-23.

“Only when sufficient reserves enable a 100 per cent HRWS seasonal determination in 2022-23 will a seasonal determination against low-reliability eater shares be made,’’ the outlook said.

“In these systems, the necessary reserves for HRWS in 2022-23 are yet to be established.

“It is possible that a LRWS seasonal determination will be announced in these systems this season, however, significant increases in resources are required.

“Significantly reducing this season’s commitments from tributary flows and additional inflows to storage later in the season are the key drivers to enabling an allocation to LRWS.”

G-MW water resources manager Mark Bailey said the good catchment conditions meant that if above average rainfall occurred in the next three months — as is expected — it will add to 2022-23 reserves,.

“Reserves for 2022-23 are being established in the Murray, Goulburn, Campaspe and Loddon systems, as the seasonal determination has reached 100 per cent of HRWS in each system,” Dr Bailey said.

“The Broken, Bullarook and Ovens systems are annual systems and water availability will depend on seasonal conditions and inflows closer to the start of 2022-23.”

For G-MW’s unregulated systems, the positive outlook means restrictions are unlikely in the larger streams, while the smaller tributary streams may still experience restrictions.

“The outlook is similarly encouraging for groundwater licence holders, with many likely to have access to 100 per cent of their allocation in 2022-23,’’ Dr Bailey said.

He said G-MW was continuing to strategise for a future with more limited resources, despite the positive short-term outlook.