Goulburn-Murray Water has announced it intends to remove five pumps from a northern Victorian lake, used to supplement regional irrigation areas.
In 1968 Greens Lake was established as an off-stream storage facility to supplement the Waranga Western Channel that supplies water to the Rochester and Loddon Valley Irrigation Areas
GMW said it was not closing the lake, which is an irrigation storage facility but changing the way it operated it.
“Independent modelling has found there will be no impact of irrigation demand or the reliability or the irrigation system,” GMW’s Water Savings and Environment manager Ross Plunkett said.
GMW’s modelling found there would be a positive impact, through reduced net evaporation and increased end-of-valley Goulburn River flows.
Historically, GMW transferred water into the lake through a gravity pipeline from the WWC and used it as a storage facility. But it found the Connections Project was creating a much more efficient, and effective, irrigation delivery network.
Greens Lake would no longer be needed to support channel operations.
Water Resources Manager Mark Bailey said the water savings generated by removing the five pumps were unregulated flows.
“These entitlements do not have a high-reliability or low-reliability component because the savings only exist if tributary flows are not harvested to Greens Lake,” Mr Bailey said.
“This form of saving would not benefit GMW customers, because the entitlements cannot be stored for use when demanded.”
GMW said the lake had not been used for the past six years.
When the pumps were operating, irrigators bore the cost of up $200,000 a year.
Construction of a pump station and pipelines at Greens Lake started in 1966 and opened in October 1968.
Any surplus flow on the channel during late winter or early spring was being diverted to the lake, through a pipeline under gravity.
It was later used during periods of peak demand, to manage flow.
Supplements from Greens Lake are pumped to the Waranga Western Channel through the same pipes used for gravity supplies to the storage.
Three pumps deliver 80.5 megalitres a day, with the other two delivering 122 ML/day. The maximum discharge with all pumps operating is 490 ML/d.
Loddon Valley irrigators Laurie Maxted and Ken Pattison questioned the decision.
“Why would you decommission something that could be an asset to you, in the future?” Mr Maxted said.
“I can’t see any logic, especially when you are coming into drier times.”
He said G-MW would only have to spend $15,000-$20,000 a year to keep the pumps operational.
“We might be grateful for another three to four per cent more water.”
“I don’t think it’s got any merit – I know there will be a water-saving component to it, but we are not going to see any of that water.”
Mr Pattison, Durham Ox, estimated the lake contained 8000ML of water and it should be used to bring entitlements up to 100pc.
“I think its blue sky savings, designed to take the water off G-MW’s bulk entitlements and give it to the Connections project,” Mr Pattison said.
“It will be real water, and we will, yet again, be dudded.”
But Rochester-Campaspe Water Services committee chairman Richard Anderson said he didn’t have a problem with closing the lake.
“It costs a couple of hundred thousand dollars, even when they are not using it.”
Closing the lake would not affect entitlements or determinations.
“It was only ever used to dump water into, and pump it out, to meet peak demand,” he said.
He said the lake was likely to retain water, but would never now be deliberately filled.
“It was there for a big rainfall event, out of the blue so that we could capture and use it.”
Mr Anderson said if Loddon irrigators wanted to keep the lake open, they should pay for it.
G-MW stressed it was not closing the lake, merely changing how it would operate it.
Connections Project Director Frank Fisseler said G-MW fully understood the recreational value of Greens Lake to the local community and recreational users, across the state, and wanted to reassure them it would remain open.
“That is why we have engaged a landscape architect who will work with the community to develop a master plan for the area,” Mr Fisseler said.
“GMW was recently successful in securing a $200,000 Victorian Government grant to improve the toilet facilities, and this is about improving on that.”