Liberal Sen Mary Jo Fisher wants the State and Federal Governments to get on with planning a desalination plant for the State's capital and to leave the River Murray water for the people "whose livelihoods depend on it".

Her comments have been a hot topic in recent weeks on talkback radio in Adelaide, and would be music to the ears of irrigators in the northern half of the basin used to familiar calls for more water to be sent down the river to Adelaide.

But in a Senate inquiry into the impact of climate change on agriculture, Federal Government officials and water scientists confirmed there was no planning work under way to develop an alternative water supply for the city.

"There should be a plan to take Adelaide off the River Murray," Sen Fisher said.

"We are the only city that draws upon it, and we shouldn't.

"The water should be left for those that have forged their livelihoods along it.

"Instead of wasting their time distracting us with water restrictions that achieve nothing, they should be focusing on weaning Adelaide off the Murray."