Critically Endangered Darling River Snails Found at Walgett Weir

A critically endangered aquatic snail has been discovered in western NSW, with ecologists surprised by how human-made water infrastructure that once threatened the molluscs has become their homes.

The once-abundant Darling River snail was feared extinct until colonies were identified in weirs on the river at Wilcannia and Louth from late 2024. A tiny colony of about 50 living snails has been spotted more than 700 kilometres upstream at a weir near Walgett on the Barwon River, which flows into the Darling-Baaka River.

It was the first time Tyrin Hickey had seen the aquatic creature.

"It sort of felt surreal," he said. "I've seen them on the internet in photos, but in my mind it didn't match up, so I was a bit anxious to see if it was the right snail or not."

The find has been deeply significant for the Ngarrangarra-li Walaaybaa Rangers in Walgett, who are backed by the Dharriwaa Elders Group. Ranger Tyrin Hickey, 31, had never seen a Darling River snail in the wild before.

Charles Sturt University river ecologist Martin Mallen-Cooper described the development as "unbelievably exciting". The construction of weirs and irrigation systems have been considered one of the contributing factors in the snail's decline since the 1960s.

"It's a glimmer of hope that you can actually create habitats and add flow, and you'll get some of these species back," he said.

Aboriginal rangers in Walgett confirmed the discovery in September through the Australian Museum. They plan to explore a second location nearby after a snail shell was found on a riverbank last week.

Senior ranger John Sands, 56, estimated it had been more than 30 years since he last saw one, but he never lost hope they would reappear.

"I grew up on the Namoi River [a tributary of the Barwon-Darling] and seen them when I used to go swimming every day," he said. "I was very excited because I always believed they were still there."

The rangers said the Walgett colony had dozens of specimens of young and old shells. Mr Hickey said it showed they had been breeding, which was a positive sign.

"We're definitely fearful of the snail disappearing again," Mr Hickey said. "They were found near the running water at the base of the weir, so we're hoping that algae blooms and the warmer water and less running water doesn't have an effect on them."

The state government said it was undertaking a "critical dietary analysis" of the snail and was working towards a research project with traditional owners to translocate and repopulate it.

"The discovery of cryptic populations of threatened species is always exciting," a spokesperson for the NSW Department of Primary Industries and Regional Development said.

A dedicated snail facility at the Narranderra Fisheries Centre in the Riverina houses about 4,000 snails bred from 2,200 rescued from the Louth weir.

Professor Mallen-Cooper said the Walgett discovery further supported research.

"Here's a threatened species surviving and thriving in these tiny habitats," he said. "This is an absolute glimmer and we ought to build on it."