THE Federal Government won't say whether it is negotiating with the owners of Australia's largest irrigation property to purchase its water entitlements.

Recent record rain in central Queensland is helping to fill the massive water storages on Cubbie Station, near Dirranbandi.

The cotton-growing station can use as much as 500,000 megalitres of water in a good year, but its holding company is in voluntary administration after years of drought.

The government has $100 million to spend on water buybacks in the Lower Balonne catchment which takes in Cubbie Station.

But Water Minister Penny Wong is reluctant to say whether the government is keen to get its hands on the station's water entitlements.

"That will be a matter for Cubbie and for the department," she told ABC Radio today.

"We don't disclose any discussions that are had or not had between any particular bidder."

The government was keen to talk to willing sellers about purchasing their entitlements at "value for money".

The lower Balonne system had been identified as a high priority for environmental water recovery, Senator Wong said later in a statement.

Water purchases would deliver long-term benefits by providing additional water to key environmental assets such as the Culgoa Floodplain and the Ramsar-listed Narran Lakes.

As at February 28, the government had secured the purchase of 798 billion litres of water entitlements for the Murray-Darling Basin's rivers and wetlands, worth some $1.27 billion.