Planned summer water transfers to meet downstream demand will be delivered as a series of pulses through the lower Goulburn River, rather than a steady flow, to help minimise damage to the river bank.
From December 14 flow in the lower Goulburn river (below Goulburn Weir) is expected to increase from the recommended 800ML/day to up to 3000ML/day to meet downstream (Murray River) water demands from towns, irrigators and the environment. Higher flows of between 2000ML/day to 3000ML/day could continue well in to 2019 if conditions remain dry and demand remains high.
Higher flows of between 2000Ml/day and 3000Ml/day could continue well into next year if conditions remain dry and demand remains high.
‘‘We share the community’s concern that high unseasonal flows could damage the bank-stabilising vegetation that had started to re-establish and spread thanks to previous environmental flows,’’ Goulburn-Broken CMA chief executive Chris Norman said.
He said since river regulation, winter and spring flows had been captured and stored in dams such as Eildon and then released during peak demand periods in the warmer months.
Mr Norman said this meant rivers generally flowed higher in summer than they would have under natural conditions.
Water for the environment is generally delivered at variable rates between autumn and spring to mimic the natural flows that would have occurred before flows were captured, stored and diverted via dams, weirs and channels.
Mr Norman said modelling showed that this year, if the water had not been stored and diverted, Goulburn River flows of more than 20000Ml/day (about Shepparton’s minor flood level) would have occurred in August and September after rain in parts of the upper catchment (above Eildon).
‘‘After seeing the impacts of the high unseasonal flows delivered in summer and early autumn this year, we have worked closely with river operators to ensure that whenever possible, future water transfers in summer and early autumn are delivered as a series of pulses, as this is better for river bank health than a steady flow,’’ Mr Norman said.
Flows in the Goulburn River between Eildon and Goulburn Weir may be increased to meet the downstream demand.
Hydroelectricity generation may also affect river heights in this section of the river.
Mr Norman said Goulburn Broken CMA would continue to monitor bank vegetation at various sites along the lower Goulburn River to measure the impacts of high unseasonal flows.
‘‘We know that the Goulburn River is the lifeblood of this region, providing numerous economic, recreational and environmental benefits, which is why we will continue to keep the community in the loop about how the river is being run and why they are seeing these changes in river height and flow,’’ he said.