Communities, farmers and environmental managers are expected to record their lowest ever levels of water use in supply systems operated by the region's system manager, Goulburn-Murray Water (G-MW).
Since the end of the irrigation season in the channel irrigation areas on May 15, G-MW has been collating end of season data, and preliminary estimates indicate only 578,000 megalitres of water was delivered in G-MW's irrigation areas.
G-MW managing director, David Stewart, said the 2008/09 Irrigation Area deliveries are barely a third of the average for the past 15 years.
Over the past 15 years, which include at least 12 years of drought, deliveries in the irrigation areas have averaged 1,800,000ML.
"The record low deliveries are a direct result of low allocations and customers choosing to carryover 2008/09 allocation to the 2009/10 season," Mr Stewart said.
Deliveries to irrigators and other water users on rivers and streams outside the irrigation areas are continuing through to 30 June 2009.
Final measurements, including meter readings will need to be taken and G-MW's end of season system performance data will not be finalised until after 30 June 2009.
Due to low inflows into the Goulburn and Murray systems allocations were restricted to just over 30 per cent - the second lowest allocation for the Goulburn System and the lowest ever for the Murray System.
With the cooperation of customers, G-MW at times didn't run 20-30 percent of its 6300 km channel network; required customers along sections of the network to group their orders; ran channels at lower levels which impacted flows onto farm; and tankered in stock and domestic supplies.
"The way we have run the system this year is very different to normal operating arrangements," Mr Stewart said.
"Our final system performance figures will not reflect the amount of water we would have lost if our customers hadn't worked with us and accepted extraordinary service levels that are simply unsustainable for G-MW and for our customers."
Carryover was extended to all irrigation systems for the 2008/09 season, and this year the carryover limits were increased to allow customers to carryover 2008/09 season allocation equivalent to up to 50pc of their high and low reliability water shares.
"Final numbers will not be confirmed until 30 June, but current indications suggest carryover by irrigation customers in the G-MW areas will be 155,000ML this year, almost the same as last year's volume of 156,000 ML," Mr Stewart said.
"We are looking at the lowest deliveries on record and as a result the lowest ever system operating requirements.
"But the results also show that in dry years like 2008/09, our system operating requirements (losses) eat up a larger proportion of our very limited water resources."
G-MW's preliminary estimates indicate system operating requirements in the irrigation areas are around 343,000ML, down from 372,000ML last year.
"Despite significant effort to minimise losses, the volume of loss is very high in comparison to the volume delivered - this is not acceptable especially if we are to meet challenges of a hotter drier future," Mr Stewart said.
"The results highlight the need to reduce losses and increase the delivery efficiency though modernising the supply system."
Mr Stewart said the performance of automated sections of the channel network had been exceptional.
"We are very excited by some of the early data and will look to share this with the community shortly," he said.
"Tools such as channel automation that can help us improve how we deliver water when and where it's needed, as efficiently as possible will help our region respond to the challenges of climate change and drought."
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