Bookpurnong Road, a major Riverland thoroughfare connecting the towns of Berri and Loxton, has been cut off by floodwaters for weeks.
But authorities said the damage could have been much worse, as works get underway for its reopening.
The news will be welcome relief for the 5,000 vehicles per day that usually travel along the road and have had to use significant detours.
"People have had to travel around an extra 50 kilometres, an extra half hour out of their day," Department for Infrastructure and Transport chief executive officer John Whelan said.
"So it's important for us to get this open as quickly as possible, as well as all our other roads and as well as our ferries."
Repairs will be required for an estimated 1,200km of roads, after the River Murray floodwaters wreaked havoc across communities.
The government has allocated $60 million from its existing flood relief package to rebuild such roads.
Premier Peter Malinauskas said Bookpurnong Road should be "up and running" in about a week.
"Safety has to be the first priority but I think everyone's very conscious of the inconvenience that road closures has brought upon different communities," he said.
But engineers have not been able to assess all of the flood-affected roads, with some still inundated.
As well as roads, up to 3,300 properties – including 360 principal places of residence – have also been identified as needing repairs.
People whose homes have been badly damaged or destroyed will be able to apply for tax breaks, under an announcement by the government today.
That includes stamp duty relief of up to $48,830 on the purchase of a new home for people whose primary residences have been substantially damaged or destroyed.
Treasurer Stephen Mullighan said the effort was focused on people who have to move "because it's uninhabitable" for them".
"The last thing they deserve is to cop another bill from the government potentially in the tens of thousands of dollars from something like stamp duty," he said.
People who need to purchase a new car to replace one that was destroyed or lost in flooding can receive stamp duty relief of up to $2,816 on the purchase of a new vehicle, or up to $2,127 for a commercial vehicle.
Land tax relief will also be available for some businesses, long-term residential rentals and some holiday rentals where financial loss can be proven.
"We know the hard work is now going to start," Mr Mullighan said.