Wet conditions during September have increased the risk of spill in the Campaspe system, in northern Victoria.
Northern Victoria Resource manager Dr Mark Bailey said the risk remained unchanged in the Murray and Goulburn systems.
In the three systems, irrigators are able to carry over up to 100 per cent of their high and low reliability water shares.
When seasonal determinations are higher than 0 per cent, holders may have more than their total high and low reliability water share entitlements.
Any water above the share volume is quarantined in a spillable account and may be lost if the storage fills and overflows the dam wall.
In the case of a spill, the Resource manager deducts a proportion of all the spillable water accounts, based on the volume which overflows.
Dr Bailey said flows into Lake Eppalock during September were well above average and the storage began to spill late last month.
Releases from Lake Hume and Lake Eildon to manage water levels also occurred throughout September and into October.
"The Eildon and Eppalock releases will cause deductions from Goulburn and Campaspe spillable water accounts respectively," Dr Bailey said.
"The quantity will be confirmed in the October 17 seasonal determination announcement."
Deductions from Murray spillable water accounts would occur if low-reliability water share seasonal determinations increased and allocation was transferred into those accounts.'
Dr Bailey said the assessments did not describe the chances of flooding this season.
"The risk of spill is a water accounting assessment. It does not refer to flood risks downstream of the storages," he said.
Allocation trade from New South Wales to Victoria is currently limited to the lesser of a net annual volume of 200 gigalitres or a volume that keeps the risk of spill from Victoria's share of both Lake Hume and Dartmouth Reservoir below 50 per cent.
Presently, allocation trade from New South Wales to Victoria is not possible because Victoria's shares of Lake Hume and Dartmouth Reservoir are full.
The opportunity for allocation trade is updated with each risk of spill announcement.
