Water

Goulburn-Murray Water responds to questions about Greens Lake

By Alana Christensen

Goulburn-Murray Water will shut down irrigation access to Greens Lake, citing the high cost of maintenance of pumps and the storage’s negligible contribution to irrigation supplies in the past five years.

Although relatively small, with a total capacity of just 28000Ml, the storage was created in the 1960s to contribute towards irrigation supplies through the Waranga Western Channel downstream of the Corop lake.

However, G-MW said the annual cost of pump maintenance was about $200000 and there was an impending cost of replacement of the pumps which had been estimated at $3million.

A Goulburn-Murray Water spokesperson responds to questions behind the decision below.

Q: What is the annual cost of maintaining the pumps?

When the pumps are in use at Greens Lake it costs GMW about $200,000 each year in operating costs – all of which is funded through fees charged to irrigators.

In addition, replacement of the aging pumps in the coming years will cost about $3 million. There are also ongoing maintenance and electricity costs in keeping the pumps on standby.

Q: Why hasn’t any of the Greens Lake water been used to supplement flows in the channel systems over the last five years?

Greens Lake was established in 1968 as an off-stream storage facility to supplement the Waranga Western Channel (WWC) that supplies water to the Rochester and Loddon Valley Irrigation Areas.

Historically GMW transferred water into the lake via a gravity pipeline from the WWC and used it as a storage facility to ensure supply for irrigators in the Rochester and Loddon Valley region.

The $2 billion Connections Project is creating a much more efficient and effective irrigation delivery network and for almost six years Greens Lake has not been required for use as a storage facility to support channel operation and also will not be needed in the future.

Q: Is any of the 28,000 Ml water capacity accounted for in irrigation allocations?

The volume in Greens Lake has been included in Goulburn seasonal determinations, but will not be included from the start of the 2019/20 season.

Independent modelling of system behaviour shows the removal of Greens Lake from the Goulburn system has no impact on seasonal determinations against high-reliability water shares.

Q: Will the ‘status’ of the water held in Greens Lake change?

The water sitting in Greens Lake will no longer be available for Goulburn-Murray Water to use to support the Goulburn system or the operation of the Waranga Western Channel.

Recreational access to Greens Lake will continue. The lake will return to its natural watering regime.

Independent experts have modelled what this means for water levels and they’ve found under current climatic conditions a permanent water pool is likely to be retained 99 per cent of the time.

Q: Can any of the Greens Lake water be sold into the irrigation system?

The water savings generated from the removal of the five pumps at Greens Lake are unregulated flows, which will be assigned to the Victorian Environmental Water Holder as an entitlement.

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.

This form of saving would not benefit GMW customers, because the entitlements cannot be stored for use when demanded.

Q: Will the drains between Lake Cooper and Greens Lake continue to operate?

This infrastructure will remain in place.

Q: Are there any savings for GMW in shutting down the pumps?

Yes. As noted, when the pumps are in use at Greens Lake they cost about $200,000 a year, funded through fees charged to irrigators. The removal of the pumps at Greens Lakes will mean GMW customers will no longer have to finance the maintenance of this asset.

It also means the aging pumps will not need to be replaced in coming years. For GMW this means an avoided replacement cost of about $3 million. This cost saving approach is clearly aligned to GMW strategic asset management objectives and is consistent with our transformation goals, which is to provide efficient and affordable service to our customers.

For irrigators the benefits are not just a reduction in costs. The works will be funded by the Connections Project, because it will also generate long-term average annual water savings.

Q: What was the purpose of connecting Greens Lake to the Waranga Western Channel?

As noted, historically GMW had this connection in place to use Greens lake as a storage facility to ensure supply for irrigators in the Rochester and Loddon Valley region. This meant water could be drawn from Greens Lake during periods of peak demand to maintain supply to irrigators in the Rochester and Loddon Valley irrigation areas.

Modernisation of the irrigation delivery network has meant Greens Lake has not been required for use as a storage facility to support channel operation and will not be needed in the future.

Q: Will water be supplied to Greens Lake from the Waranga Western Channel?

Under current system operations Greens Lake had been retained to accommodate peak flows along the Waranga Western Channel, however these peak flows are far less common under current demand scenarios, and can be accommodated through scheduling.

The pipe infrastructure that allows water to be gravity fed into the lake will remain, so the lake will be available for emergency outfalls and environmental water.

Q: Wasn’t there a management plan completed about five years ago for Greens Lake, including community consultation?

The Greens Lake Land and On-Water Management Plan was established by GMW in 2014. It provided five-year program of priority implementation works and a strategic approach to management of land and on-water issues at Greens Lake.

As part of the plan, a Greens Lake Community Reference Group has been established. This group includes representatives from Local Government, the community, the Corop Community Action Group and the Rochester Water Services Committee.

Q: Why is GMW spending time and money on upgrading a recreation area?

The works will be funded by the Connections Project.

The Project and GMW understands the recreational value of Greens Lake to the local community and recreational users across the state and we want to assure them the lake will remain open.

GMW was recently successful in securing a $200,000 Victorian Government grant to improve the toilet facilities at Greens Lake.

We’re currently working with the community to understand which facilities are important to them at Greens Lake. This has included workshops, drop-in sessions and an online survey and there will be more opportunities for recreational users to participate. For more information visit our website at www.connectionsproject.com.au.

Q: Will irrigators have to bear any costs for the Greens Lake plan?

No. Irrigators do not fund recreational use of our storages. The plan to remove the pumps at Greens Lake will represent a net saving for irrigators through avoided maintenance and significant future replacement costs of the pumps.

Q: If Greens Lake no longer contributes water to the channel system, wouldn’t the area be better managed by a body like Parks Victoria?

Current management responsibility for the Greens Lake foreshore rests with GMW.  As the manager of the storage and surrounding land, GMW is also responsible for managing access to the site for recreation.

The masterplan we’re developing with the community and recreational users will set out a strategy for improved recreational facilities and landscape design at the lake and provide the basis for discussions about ongoing management responsibilities and costs.