Initial results from recent monitoring show the high volumes of water traded and transferred to downstream Murray users during summer - known as inter-valley transfers (IVT) – is damaging important streamside vegetation and leading to increased erosion.
Scientists from Arthur Rylah Institute (ARI) and Streamology carried out bank vegetation and bank condition monitoring last month at sites along the lower Goulburn River as part of the Commonwealth Environmental Water Office’s four-year Monitoring Evaluation and Research (MER) program.
The monitoring showed there is narrow band of healthy and diverse vegetation at or slightly above the level influenced by IVT flows, but below this level there is generally no vegetation. Where bank vegetation had been drowned out on the lower banks, bank notching occurred, and tree root structures were being affected. These factors increase the likelihood of erosion and further bank instability.
More bank and vegetation monitoring is due to be carried out later this month.
The MER Goulburn project also monitors native fish breeding, populations and movement; water bugs; and river health. Find out more about the program at https://www.environment.gov.au/water/cewo/monitoring or follow Goulburn Broken CMA on Twitter, Facebook or Instagram.
Please note: Summer IVT flows are to deliver traded water to downstream users, not environmental flows for the Goulburn River.
Last year the Victorian Government introduced interim operating rules in response to environmental damage from recent high summer flows and Goulburn Broken CMA and community concerns about the impact of the record high summer IVT flows (2017-18 and 2018-19) of on the river’s banks.
The interim rules aimed to limit IVT deliveries to a maximum of 50GL/month with fluctuating flow rates during summer 2019-20. Deliveries we maintained at or below 50 GL/month for most of the summer period, however river operators required 61 GL to be delivered in January in response to very high demands for water downstream.
On March 16 IVT deliveries were cancelled for the rest of the month and since then the river’s flows have been at a more typical rate for this time of the year of around 900ML/day. If no more IVT is delivered this irrigation season, the return to lower flows may give the banks a chance to dry out and some of the vegetation to recover. Visit Goulburn-Murray Water’s website for more information on river operations.
The Victorian Government is currently seeking community input on proposed changes to the Goulburn to Murray trade rules - visit https://engage.vic.gov.au/goulburn-murray-trade-rule-review to have your say.