RED tape threatens to stem the flow of almost $400 million for the River Murray, irrigators and consumers warn.

Businesses are yet to receive $265 million announced with fanfare last October and there are concerns the money will get bogged down in criteria that make it difficult or impossible to access.

Almost $100 million from a different $110 million fund for water efficiencies has languished unclaimed for four years because the criteria determined by the Federal Government is "one size fits all" and doesn't fit South Australia, critics say.

SA River Communities spokesman Ben Haslett said the state had been forced to be ahead of the curve on water efficiency, so in many places good infrastructure was already in place and they now needed funds for more innovative ways to save water.

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But if criteria is formed with the other less-advanced states in mind that means it's harder to access.

"We need the Federal Government to be as innovative as they are asking these regional communities to be," he said, adding that Riverland businesses needed access to the funds for diverse projects such as plantings or property purchases for economies of scale, rather than for basic infrastructure that most people already had in place.

Independent Senator for SA Nick Xenophon said the promised money was starting to "look like a mirage, an oasis".

"I'm worried the Federal Government is playing games with us on this," he said.

Mr Xenophon said the money should be there to "future proof" the Riverland, but river communities were "banging their heads against a bureaucratic brick wall".

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The Federal Government is currently finalising the details of the $265 million funding and Water Minister Tony Burke said there was "no problem".

"The reason for the delay is only that the precise nature of each project hasn't yet been finalised, but every dollar reserved for SA remains reserved for SA," he said.

The earlier, $110 million Private Irrigation Infrastructure Program funding, is still being held for future, yet-to-be-finalised projects.

Central Irrigation Trust chief Gavin McMahon said SA was already efficient and now needed help to make businesses more robust.

"People are looking forward to (the funding) and prepared for it," he said. "I struggle to see the difficulty the Commonwealth is having on the criteria".

Originally published as Red-tape delay to $400m in river funds