SA Democrat MP Sandra Kanck said South Australia's federal representatives should work together to give the government the power to seize water to improve environmental flows.

"This means that as soon as non-critical water is identified it can be seized, the water holders compensated and the water used to revive the Murray, the Darling and the lower lakes," Ms Kanck said.

"That is in the long-term interests of all the farmers and the communities that depend on our rivers, not just South Australians."

Ms Kanck said without the power to seize water entitlements the government's water audit in the Murray-Darling Basin was worthless.

"It will show us how much water is in the system but we still won't be able to get at it," she said.

"State governments routinely acquire land for roads and airports.

"We must give our federal government the power to acquire the most precious resource of all."