As the environmental benefits of the Murray Darling Basin Plan are once again thrust into the spotlight, the Commonwealth Environment Water Holder is outlining its early season plans for southern river systems.
It's exceptionally dry across the Basin and the CEWH is planning to open its account for environmental watering events soon to give the parched landscape a drink.
The initial plan is to piggyback pulses of environmental water on top the significant flows, around 8000 megalitres a day, which river operators are currently running downstream of Yarrawonga in response to demand from entitlement holders.
The CEWH is set to send down two pulses from the Basin's dams, most likely in early August and the other in September. It will also coincide with an ongoing environment flow in the Goulburn River.
Timing depends on operational delivery, but the pulses will coincide with high flows to enable the river to hit a flow of 9500ML/day, pushing it to overbank capacity.
Water will spill into the Barmah-Millewa forest, which stretches between Tocumwal, Deniliquin and Echuca to form an expansive 28,000 hectare wetland covered with River Redgum forest.
As flood water slowly makes its way back off the floodplain into the river nutrients will be washed back, fuelling growth in the ecosystem, giving important habitats a drink and hopefully boosting fish stocks in the process.
Water delivery to last year's high demand from permanent plantings, downstream of the Barmah Choke, resulted in unusually persistent high flows and extended periods of inundation for the Barmah forest.
The resulting river bank erosion and over-inundation of moira grass was a concern for many.
This year the CEWH wants to direct the flow to the Millewa side of the forest, which is on the NSW side of the river.
An overbank flow, timed properly, could avoid erosion as it goes above the bank, and by varying the water level as the pulse raises and lowers the water level, prevent a consistent, persistent flow rate carving a notch into bank.
"These releases of fresh water are the heartbeat of the river - they keep our plants and animals healthy and improve water quality. Without them, the river's lifeblood stops flowing," said CEWH Jody Swirepik.
The CEWH carried over 420 gigalitres into this water year, which began on July 1. In combination with environment water held in state accounts, the total environment water available across the Murray, Goulburn and Murrumbidgee catchments is around 600GL
Pulses may amount to a total of 300GL, but the final volume is contingent on river flow.