Across 2018-2019, an environment flow of 110,000 megalitres was released to inundate Yanga National Park, flows terminating in Yanga Lake.
But just months later, Yanga Lake, just south of Balranald in the Western Riverina, is set to dry up.
A spokesperson from the Department of Planning, Industry and Environment (DPIE) stated the environmental flow had successfully provided habitat for nesting egrets and Australasian Bitterns in the upper wetland systems of Yanga National Park.
"An estimated 5,000ML made its way through all the upper red gum forest, swamps and lakes and entered Yanga Lake," the spokesperson said.
"The flow provided for native fish outcomes throughout the system, including in the Lake."
However, they stated given the lake's large size, significant capacity, combined with difficult logistics for water delivery, Yanga Lake had not been identified to receive any further water for the environment at this time.
"Providing an effective volume of water to Yanga Lake this summer would have required using the entire environmental water available for the Lower Murrumbidgee Valley this year," the spokesperson said.
The outcome has left some water management advocates wondering whether filling the lake in the first place was a waste.
Concern drying out lake supported feral pig population
Yanco and Colombo Tributaries Advisory Council president, Bob Crawford said the project seemed to be "doomed to fail."
"The lake is drying up rapidly and the fish are all getting caught in ponds, the birds are having a field day," Mr Crawford said.
"It's been a free for all for feral pigs, there's tonnes of food, tonnes of water, any pig worth its salt would go there."
Former landholder, Gwen McLaughlin questioned the purpose of watering the floodplain.
"It seems that the water was used to grow fish to feed mostly pelicans and grow noxious weeds, pigs and deer," she said.
"If the water had been used on rice crops similar ecological results would have been achieved but without the shutdown of the rice industry."
However, Environmental Water Advisory Group Murrumbidgee member, Dr Dale McNeil said nine years out of ten the environmental flow would have worked, but this year follow up rain just didn't come.
"Usually, with more water around, the pelicans wouldn't have been able to come in and smash the population," Mr McNeil said.
"But during these extremely dry periods, when the water does go down, that's when the birds can come in and eat lots of fish.
"This happens in natural systems and the pelicans and other birds can now survive because of the food web switched on by environmental water."
Dr McNeil said at an EWAG meeting last month, Balranald locals questioned why Yanga wasn't prioritised for water this year.
He said the Department explained that they knew most of the fish had died as the lake was drying out, so refilling it wasn't going be as effective as using the small amount of water available to protect several other high-priority sites.
