Flows in the Goulburn River are starting to increase to meet demand from Murray River users.
The increased flows are not environmental flows for the Goulburn River.
The Murray Darling Basin Authority has placed an order for 50 gigalitres to be delivered from the Goulburn, this month, to meet downstream Murray River demand and maintain water in Lake Victoria - a key storage for South Australia.
Goulburn Broken Catchment Management Authority (CMA) has asked the inter-valley trade flows be delivered at a variable rate, to limit environmental damage to the Goulburn River.
"We'd prefer to maintain the flow around 1000 megalitres/day to give bank vegetation a chance to grow and spread and provide valuable habitat for bugs and small fish," Goulburn Broken CMA chief executive Chris Norman said.
"Higher flows in the Goulburn at this time of the year, when you'd expect flows to be low, cause environmental damage such as erosion.
"We've used water for the environment in spring for the past five years to help spread the seeds and plants that help stabilise the banks and provide shelter for native fish and wildlife."
Mr Norman said monitoring showed water for the environment was making a difference and that the banks were starting to recover from the last drought and floods.
"Unfortunately the record high IVT deliveries over the past two years during summer and early autumn have undone some of the good work we were starting to see," Mr Norman said.
"They've caused erosion of the lower bank and loss of bank-stabilising vegetation, which means the banks are now even more vulnerable to these high unseasonal (IVT) flows."
Mr Norman said the CMA's preferred option was that if water was to be delivered at this time of the year, it would be in a variable rate, with a short higher 'pulse' of water, in mid-December, rather than delivering it at a constant rate, over a longer period of time.
Recently the Victorian Government announced IVT deliveries would be limited to 50GL a month from December to April, to help reduce environmental damage to the lower Goulburn River caused by high IVT deliveries during 2017-18 and 2018-19.
The MDBA order will see flows in Goulburn River increase from the current IVT rate of 1300ML/day to an average of 1700ML/day.
Flows in the lower Goulburn River (downstream of Goulburn Weir) will fluctuate around 1300ML/day, with a plus of about 3000ML/day delivered in the middle of the month.
Flows will then return to around 1300 ML/day.
The effects of IVT and unseasonal high flows on the banks will continue to be monitored by the Goulburn Broken CMA.
For more information on interim changes to Goulburn River operations visit: https://www.water.vic.gov.au/planning/victorias-entitlement-framework/trading