A press conference is currently underway providing media with more details of the sale.

But in a statement to the Australian Stock Exchange this morning, Tandou said the Murray Darling Basin Ministerial Council has approved an in-principle agreement with the NSW Department of Environment and Climate Change to sell 250 gigalitres of Tandou's supplementary water for $34m.

Tandou was established in 1972 as a private company growing irrigated cereals and cotton, and grazing Merino sheep, centred around the vast, ephemeral Lake Tandou, 50km south of Menindee, NSW.

"This in-principle agreement is a wonderful result for Tandou and also for DECC in securing a significant volume of water for the environment which will assist in achieving NSW's Living Murray objectives," Tandou chairman Dick Warburton said.

"The company's remaining water entitlements are valued at approximately $30m based on a recent independent valuation, and this equates to 34c per share.

"Importantly the company has retained its higher reliability entitlements (general and high security regulated water licences) on the Lower Darling, NSW Murray and Murrumbidgee River systems and will continue operating Tandou Farm and its horticultural operations at Menindee, NSW, in the future."