Goulburn Broken Catchment Management Authority’s sustainable irrigation program manager Carl Walters said that could be enough to trigger blackwater events.
“We are monitoring the dissolved oxygen at a number of locations daily; it really depends on how much it rains, but if we got 50mm in some of those dry areas we would likely see vegetation wash into waterways,” he said.
Blackwater events occur when rotting organic matter and high temperatures combine to cause low levels of dissolved oxygen in water, which can be harmful to fish and other aquatic species.
The CMA has monitoring stations along rivers, creeks, and streams to act as an early warning system.
“We have had a bit of a decline in dissolved oxygen in the Broken Creek in recent weeks,” Mr Walters said.
Sites are monitored daily and the CMA staff meet with Goulburn-Murray Water staff once a week to discuss scheduled water movements and interventions to break up blackwater.
Mr Walters said managing blackwater was not as simple as sending a flush of water from the top of the system downstream.
“Water doesn’t pass other water, so it just pushed the blackwater along,” he said.
On the Goulburn and Broken rivers and Sevens and Broken creeks there are multiple points where water can be released to counter a blackwater event.
“If we can be aware of what it is and where it is, we can work out what we can do,” Mr Walters said.
“As an example, with the Broken Creek, which has a history with warm weather, we watch it pretty closely and are able to manipulate it pretty well.”
The Bureau of Meteorology expects the weather system to move into the region on Wednesday but the worst of the weather and storms will be on Thursday and Friday.
Despite the unsettled weather, the daytime temperatures will stay around 30°C with high humidity.
