Another case of excessive payments for water rights in the Murray-Darling Basin has been revealed, with the Turnbull government paying a quarter more than the seller even asked.

Eastern Australia Agriculture was paid almost $80 million in July last year for about 29 billion litres of its water licence, a price that generated the company a $52 million profit, The Australia Institute said in a report released on Wednesday.

Irrigation in Australia has come under greater scrutiny after a series of revelations about high-cost water buybacks.

Not only did the company retain more water than it sold from properties on the Condamine Balonne Valley of southern Queensland, it also held on to a dam that it had valued at $16 million and had offered as part of the deal, the institute found, based on information obtained by an Order for Production of Documents by Nick Xenophon Team senators.

Senator Rex Patrick noted the institute's comparison to a Monty Python haggling skit but said "if it wasn’t so serious, it would be funny”.