"The reason politicians won't talk about these dams is that they do nothing for drought-stricken communities, the health of the [Murray] river or struggling farmers," Ms Slattery said on Tuesday.
She has restated calls for a Commonwealth royal commission into the "mismanagement" of the Murray Darling Basin.
The agriculture department has claimed new dams collecting recycle irrigation water or replacing shallower dams could help save water, but the institute says three dams it has reviewed do no such thing.
"Taxpayers have paid for new dams that increase water use, damage the environment and exacerbate the problems of the Murray," its report said.
The institute said while public dams required public consultation, private dams allowed developers to contract private consultants to sign off the environment impact of the project.
Water Minister David Littleproud has publicly lamented the fact very few new dams have been built since 2003.
But the institute has found at least 20 new dams have been constructed on private property in recent years, funded at least in part by Australian taxpayers.
"So are we building dams or not? Apparently unnoticed by all these leaders, many new dams have been built recently in the Murray Darling Basin," the institute said.
"(New dams) are on private land, for private use, mainly by large corporate agribusiness, such as Webster Limited.
"David Littleproud is right that 'bugger all' is being done to build new public dams, and that the states play a major role in this."
New dams built in the basin have drawn funding from the Commonwealth's $4 billion water efficiency program.
Ms Slattery new dams in the Murrumbidgee Valley had the potential to dry up river flows into the Murray.
"If any other industry wasted taxpayer money on environmentally and socially damaging projects like this, there would be a national outcry," she said.