WHEN Marg Whyte moved to Willow Point Station on the Great Darling Anabranch in the 1960s, 20 miles of river snaked through her property.

She would take her children searching for yabbies, shrimps and mussels in the water and spent mornings and evenings watching birds nesting in the box trees and river red gums.

It's been "10 or 15 years" since she last saw a freshwater mussel, she said.

And a combination of regulation and reduced inflows to Menindee Lakes now mean the Anabranch is a series of remnant billabongs and pools.

Many of the birds that once lived in colonies on the property have died or moved on.

But with widespread rainfall across Queensland and NSW arriving in Menindee Lakes in recent weeks, locals and scientists are hopeful water will flush through the system again this spring after five years without water.

If the water comes, scientists say the ancient landscape will transform, bringing nutrients and fish pulsing through the system and into the Murray River, giving the whole river system renewed vigour.

Hilton Taylor, acting Commonwealth Environmental Water Holder, said the Anabranch was a "high priority" for an environmental flow after five years without water.

Naturally the Anabranch -- a river that splits from the Darling-Barka River at Menindee Lakes -- would have flowed "at least a couple of times in a decade", Mr Taylor said.

According to scientific studies published in 1993 and 2002, small floods flowed into the Menindee Lakes, northern Anabranch lakes and Darling River billabongs two in every three years.

One in 10 years moderate floods spilled on to the floodplain and filled the southern most lakes and wetlands for months to years.

But the most recent flows -- a 100-gigalitre flush in 2017 and a flow of 50GL in 2013 -- were the only times the river saw water in the past decade.

The Great Darling Anabranch is reduced to a series of remnant billabongs and pools by rare flows. Picture: Krystal Torney

The Commonwealth Environmental Water Office (CEWO) was waiting to see exactly how much water arrived at Menindee Lakes before confirming a spring flow for the Anabranch, Mr Taylor said, but indications were "promising".

According to the latest estimates from WaterNSW, up to 1000GL of water is expected to enter Menindee Lakes from widespread rainfall in Queensland and NSW earlier this year.

The lakes were this week holding more than 989GL, with inflows expected to slow over the coming week.

CEWO southern basin director Hilary Johnson said the flow depended on how much water entered Lake Cawndilla - the last in a chain of lakes in the Menindee system.

"Lake Cawndilla needs to fill up to a fair level before we can get water down the Anabranch," Mr Johnson said. "We think it is going to get up high enough."

But there were a few unknowns, he said, including how much water would disappear through seepage into the dry lake bed, and how long it would take the lake to fill.

If a successful flow down the Anabranch were possible, it would have benefits for fish populations throughout the whole Murray system.

The connection would "create a highway" for fish such as golden perch to travel from the lakes to the Murray.

If the river didn't flow "that lake dries up and that's it (for the fish)," Mr Johnson said. The fish now in the lake had "come all the way down with the floodwater".

"They come from the border rivers in Queensland," he said.

"As Cawndilla is filling up," Mr Taylor said, "it's like a nursery for these fish -- they just go gangbusters in there. "They love the nutrients in the water. It's really rich, so they grow quickly.

"And then, if we can connect the Anabranch through, that exports those fish into the Murray, and then they can go everywhere from there."

A flush down the Anabranch would also provide vital nutrients to the Murray River, Mr Taylor said.

"If you think of the Murray from (Lake) Hume all the way down past (Wentworth), it runs at a pretty constant level a lot of the time," he said.

"The channel of the Murray gets swept. A lot of the time with that water, there's not a whole lot of nutrient in it."

A flow down the Anabranch would be "like a farmer putting fertiliser on (their crop)", he said. "You get a real boost in productivity.

"(The water) picks up the fertiliser, comes back into the river, boosts that whole ecosystem and - at the moment - a whole lot of the time that fertiliser factory is disconnected from the fish. It's really important to have those connections."

Mr Taylor said reduced flows down the Anabranch over the past two decades had coincided with record low inflows to the Darling-Barka system.

Inflows had become "really variable" in the past 20 years, he said.

Over the period leading up to the most recent rain, they had been so low they had "rewritten the record books".

Leading up to the most recent rain event, "some of those low (inflow) records were 70 per cent below the previously recorded inflows".

About 50GL of water was needed to connect Lake Cawndilla with the Murray River through the Anabranch, Mr Johnson said, and the CEWO would confirm how much water it could provide to the river in spring.

For Marg Whyte, even these vital flushes won't restore the Anabranch to the river she lived alongside for 52 years.

"They used to call this the lakes district," she laughed sadly.

One of the deeper of the 16 ephemeral lakes on the Anabranch, Lake Nearie on Willow Point Station, was once considered a drought refuge for water birds in dry times.

"We had water in that lake for 10 years at one point," she said.

Mrs Whyte, now in her 80s, is dedicating her time to painting the landscapes and animals she fell in love with on the Anabranch.

She has published a series of children's stories about the creatures that call the river home, and a book she has called Death of a River, an "expression of grief" at the "theft" of water from the landscape.

Marg Whyte has written a book about the Anabranch called Death of a River. Picture: Krystal Torney

"I want the children to know all they can about the birds and the animals and the plants," she said.

"It's meant to be sad. It's meant to tug at your heart strings."

Too often, discussions about water devolved into conversations about megalitres and gigalitres, she said. But "megalitres don't tug (at your heart) like these animals do".

"Some people think people in the bush haven't got a brain," she said.

But understanding country is "about patriotism and loyalty to your area".

"I love this country."