Taxpayers have funded as many as 30 large dams on land owned by private interests and large agribusiness firms, with a new report questioning the environmental benefit to the Murray-Darling Basin.

New research by the Australia Institute think tank found at least 20 new dams have been built on private property, including in the Murrumbidgee Valley in NSW, funded in part by taxpayers through the Commonwealth’s $4 billion water efficiency program.