Wheat

Blackwater update 1

Tuesday 3 January, 2017
Blackwater moving along the Goulburn River is expected to reach McCoy’s Bridge late today/overnight
  • The blackwater event is not due to an environmental water delivery; it is a result of debris-rich run-off from tributaries including Castle, Pranjip and Seven creeks and the Broken River that entered the Goulburn River after more than 100mm of rain fell across parts of the catchment on December 29.
  • The water from the creeks includes leaf litter, sediment and other debris washed off the floodplains.
  • When high levels of organic matter enters the river, dissolved oxygen – a measure of water quality – can drop, causing stress to fish, crayfish and other aquatic animals. When the dissolved oxygen reaches a very low level it can result in fish deaths.
  • Dissolved oxygen levels in Goulburn River near Shepparton dropped overnight Saturday but have since increased and stabilised at levels suitable for aquatic animals.
  • Goulburn Broken CMA is working with Goulburn Murray Water to use environmental water to increase flows along the Goulburn to help replenish dissolved oxygen levels and disperse the black water.
  • The increased flows started on Sunday and will reach a peak of 3000ML/day over the next couple of days. This will see the river height increase by about 0.5m for around a fortnight.
  • The amount of environmental water that can be delivered is limited by river operations.
  • Fisheries Victoria staff have been monitoring the Goulburn River since the weekend.
  • Unfortunately there have been native fish deaths, including Murray cod and yellow belly, with the largest number of fish deaths recorded around the Jordan Bend/Cemetery Bend area and north Shepparton.
  • The black water is diminishing as it makes its way along the river with fewer fish deaths recorded downstream of Loch Garry. However the poor water quality may result in further deaths.
  • Fisheries Victoria is reminding people that bag and size limits still apply and that collecting spiny crayfish out of season is illegal.
  • Monitoring native fish tagged as part of a program we’re conducting with Arthur Rylah Institute, Fisheries Victoria, the Commonwealth Environmental Water Holder, MDBA and other agencies will help determine any potential long-term impacts of this event.
  • However, it is expected that fish numbers should recover quickly as native fish and other aquatic animals are resilient and will seek refuge in sections with more favourable water quality.
  • Goulburn Broken CMA is also considering an environmental water delivery along the lower Goulburn River early autumn to encourage yellow belly to migrate from the Murray River into the Goulburn River.
  • More information on managing blackwater is available here.
  • The community is encouraged to report fish deaths to the EPA on 1300 372 842.
  • For information on town water supplies please refer to the GVW website.