Additional water is being released from Goulburn Weir to help dilute debris-rich run-off from local creeks that has discoloured the Goulburn River downstream of Shepparton during the past couple of days.
Goulburn Broken CMA Environmental Water Manager Simon Casanelia said that after up to 100mm of rain fell across parts of the catchment on December 29, run-off from Castle, Pranjip and Seven creeks had entered the Goulburn River near Shepparton.
“Water from the creeks, which includes leaf litter and other debris, is making its way down the Goulburn River, causing the water to look darker in stretches,” he said.
Dozens of dead yellowbelly, cod and shrimp line the banks of the river due to the occurrence known as Blackwater, causing depleted oxygen in large stretches of river near Shepparton.
Heavy rain last week caused run-off from the Pranjip, Seven and Castle Creeks, pushing built-up leaf litter and other debris into the Goulburn.
Dozens of dead fish were discovered by fishermen Kevin Bartlett and John Giatrakos on Monday morning.
The CMA has been monitoring dissolved oxygen levels.
"The levels dropped overnight Saturday but while they appear to have stabilised, we worked with Goulburn Murray Water yesterday to use environmental water to increase flows along the Goulburn to help replenish dissolved oxygen levels and disperse the slug of dark water,'' Mr Cassanelia said.
“Unfortunately a small number of dead fish have been reported as a result of the runoff. However, native fish and other aquatic animals are generally pretty resilient and seek out more favourable water quality.”
Inflows into the Goulburn River from the creeks have already reduced.
River levels below Shepparton will rise slightly (about 0.5m) over the next few days as a result of the increased flow. Water takes about four days to reach the Murray River from Shepparton.
For more information on dissolved oxygen levels visit: http://www.mdba.gov.au/managing-water/waterquality/blackwater
The community can report fish deaths to the EPA on 1300 372 842.