Scientists have started pumping rainwater into one of the South-West's drying caves in a bid to save its prehistoric animal life from extinction.
Water levels in Lake Cave, one of three main tourist caves near Augusta, have been falling about 1mm a week over 30 years of below average rainfall and the cave's famous lake is now less than knee-deep.
Rainwater collected in above-ground tanks is being injected into the sandbank behind the cave at a rate of 150 litres a day as part of a $150,000 12-month trial launched last week.
The caves are home to ancient aquatic invertebrates, some of which are found nowhere else in the world and cannot live outside the caves.
Department of Environment and Conservation principal hydro geologist Stephen Appleyard said there were fears the cave would be dry within two years, destroying the unique worm and shrimp-like creatures.
"These little animals are basically relics of animals which used to live on the surface, many, many millions of years ago when Australia had a much wetter climate and as the climate dried out they retreated underground," he said.
"Their closest living relatives are overseas in places like South Africa and Europe. The caves are the last refuges of some of these animals and some are unique to this particular cave system.
"As far as we know, if the water that supported them disappeared, they would disappear too, but we don't really know."
Dr Appleyard said scientists were trying to replicate the way water naturally seeped into Lake Cave.
"We're trying to mimic the natural systems," he said.