The animal was found by a Mount Isa Water Board staff member on the reserve on Sunday.

It is believed the donkey died after being shot with an arrow, however the weapon was not found.

The donkey was later disposed of humanely.

Mount Isa Police Sergeant Glenn Arrold said police were investigating the incident.

"Police take cruelty to animal charges extremely seriously and this will be investigated thoroughly," he said.

Sgnt Arrold added that this type of behaviour would not be tolerated.

"Should an offender be found, while working with the Department of Primary Industries on this, we would be looking at putting him before the courts," he said.

Mount Isa Water Board chief executive officer Ian Pascoe said the attack showed people had no respect for Lake Moondarra or the environment.

"There is no respect out there (the lake) there is no question about that.

"People seem to vandalise the place, litter and now they're even shooting animals.I don't understand the logic in it."

Members of Mount Isa Water Board, the trustee of the land, had taken a liking to the donkey.

"He used to act as if he was one of the cows, grazing around with them," Mr Pascoe said.

"He was very tame, you would have been able to walk right up to him and feed him a carrot."

The attack comes just months after a peacock was attacked at Warrina Park, near Lake Moondarra.

The bird was found with a 40cm long graphite GPH arrow sticking through its body.

An RSPCA spokesperson said offenders can face a maximum $100,000 fine and two years imprisonment for animal cruelty crimes.

n Anyone with information on the attack is urged to contact Crimestoppers on 1 800 333 000 or Mount Isa Police on 4744 1130.