Water

Winter flow to support river environment

By Country News

Upper bank vegetation and water quality will benefit from an environmental flow along the lower Goulburn River, with the benefits expected to extend all the way to South Australia’s Coorong.

Water for the increased flow is due to be released from Goulburn Weir from June 20, peaking at about 9500Ml/day (4.30m) at Murchison on June 28.

The increase in river flow and height is well below minor flood level (9m at Murchison and 9.5m at Shepparton).

‘‘As much of the rain and run-off into the Goulburn River is now captured in the dams and used to supply towns, industry and farms, the amount of water flowing down the river in winter and spring has reduced,’’ Goulburn Broken Catchment Management Authority environmental water manager Simon Casanelia said.

‘‘It also means the river flows higher and faster in the hotter months of the year when communities require more water, which is the opposite of what would happen if there were no dams and weirs,’’ he said.

‘‘These changes have affected the health and survival of native plants and animals, so we’re giving nature a helping hand and delivering environmental water at this time of the year to mimic more natural flow conditions.’’

Mr Casanelia said as flows along the lower Goulburn River had been running higher than usual for the past five months to meet the increased Murray River irrigator, community and environmental demand, this year’s winter flow had been designed to decrease at a slower rate than flows delivered at the same time of year in the past.

The slower rate is designed to reduce the risk of riverbank slumping or erosion.

‘‘This year’s flow is targeting bank vegetation higher up the banks, rather than the lower bank vegetation which has been inundated for quite some time now,’’ Mr Casanelia said.

‘‘Water bugs and fish will also benefit.’’

The environmental flow will take about a week to reach the Murray River and will provide multiple downstream benefits, including supplying water to wetlands along the Murray River and triggering upstream migration and spawning of pouched lamprey, a rare and primitive eel-like fish that enters the Murray system via South Australia’s Coorong estuary.

In the event of heavy rain, the timing and size of the environmental flow could change or not go ahead at all.

■For more information, visit: www.gbcma.vic.gov.au