River Murray flooding, health and child protection spending to strip away the state's surplus, treasurer warns

Stephen Mullighan says the South Australian budget is unlikely to return to the black. (ABC News: Che Chorley)

The cost of the River Murray flooding, plus extra money needed to boost South Australia's health and child protection systems, means it will be "extremely difficult" to get the state's budget back into surplus, the SA Treasurer has said.

Stephen Mullighan said Tuesday night's federal budget revealed a forecast $95 million reduction in South Australia's GST revenue this financial year, which was about half of the surplus he was aiming for when he delivered the state's mid-year budget review in December.