Opening all the regulators on Barmah Forest’s creeks next week will help native fish movement as Murray River flows start to increase.
Flows along the Murray River below Yarrawonga are currently about 4000Ml/day and are expected to increase up to 10000Ml/day when the irrigation season starts.
Goulburn Broken CMA ecologist Keith Ward said this was the first time all 12 regulators had been opened during winter while the river flow was so low.
‘‘Traditionally, the regulators are only opened when Murray River flows downstream of Yarrawonga Weir exceed 10400Ml/day,’’ Mr Ward said.
‘‘When that happens and the regulators are opened, as you can imagine, the water has built up behind the regulator gates, creating unnaturally high and fast flows that suddenly rush into the forest.
‘‘Fish ecologists believe these sudden large ‘pulses’ of water may be detrimental to native fish recruitment, survival and dispersal.
‘‘This trial of opening the regulators in winter will see more gradual fluctuations in flows in the forest’s creeks and will help native fish move through the system, which is critical for breeding.’’
Mr Ward said higher flows would also help reduce leaf litter and other organic debris building up on the forest’s floodplains.
‘‘When this gradually washes into the river it provides valuable nutrients for native fish, water bugs and other wildlife. Reducing the build-up of leaf litter on the low parts of the floodplain during winter, when air and water temperatures are lower, also reduces the likelihood of blackwater events if we get heavy rain during the warmer months.’’
The regulator gates are expected to be open early next week and will stay open until the end of September, subject to weather and other river operations.
■For more information about environmental watering activities during 2017-18 along the Murray River and in Barmah visit www.vewh.vic.gov.au