THE sudden death of 100 corellas at Nhill Lake has been referred to state authorities.
The lake's committee of management contacted the Environment Protection Authority and the Department of Environment, Land, Water and Planning after it suspected the birds were poisoned last week.
The committee now hopes the lake's walking track can reopen this week, after it was closed due to the deaths.
President Stuart Bone said he became aware of dead and dying birds at the site on Monday last week.
The committee suspected the birds might have been poisoned. But Mr Bone said a search for a cause had not revealed any clues.
The committee closed the lake's walking track as a safety measure while it investigated the deaths.
It also contacted the Environment Protection Authority and the Department of Environment, Land, Water and Planning about the suspected poisoning.
The department's Grampians regional manager for the Conservation Regulator Brian Hamer said it was an offence to use poisons to kill, destroy or take wildlife.
"The Conservation Regulator is aware of the corella deaths around Nhill Lake and has retrieved a small number of birds in order to investigate possible cause of death," he said.
"Severe penalties (including imprisonment and fines) apply to those found guilty of an offence under the Wildlife Act."
Mr Bone said a volunteer team recovered about 100 carcasses from the lake area at the weekend.
"We don't want dead birds at all, and we don't want them decaying in the water," he said.
No more dead corellas have been discovered for three or four days.
Mr Bone said the deaths could have an innocent explanation. He said the birds usually liked to leave the lake during the day and return at night.
"It might have coincided with farmers putting out mouse bait," he said.
He said spilled pickled grain could also be responsible: "I've heard of birds, and corellas in particular, they eat pickled grain and it can actually kill them as well."
Mr Bone said as far as the committee could tell, there was no continuing threat. He hoped the walking track would reopen this week.
Mr Bone said people had reacted with disappointment and confusion to the deaths