A backlog of cars and trucks more than 15km long was ready to move at the bridge at Arundel when Scenic Route 72 reopened at 11.45am yesterday.
State Highway 1 at the Rangitata River, between Timaru and Ashburton, remains closed and will be reassessed by the New Zealand Transport Agency this morning.
Both closures were caused by flooding on Saturday as the river burst its banks and separated the north and south by road.
Wanaka and Queenstown are in cleanup mode as lake levels begin receding; however, it could take them weeks to return to normal.
Washouts and slips continue to block State Highway 6 on the West Coast and hundreds of tourists are still stranded at Franz Josef and Fox Glacier.
On Scenic Route 72 the long line of vehicles remained until late afternoon.
Timaru photographer Stu Jackson said all drivers were in good spirits despite the disruption.
"I haven’t even heard a single horn beep, for example."
It was so hot tar was melting on the road, meaning lots of "dry, thirsty people".
The chaos was being caused not by the reopened bridge, but by a one-way bridge north of Geraldine.
The closed roads continued to cause product shortages for businesses and organisations in Dunedin yesterday.
This included Dunedin and Wakari hospitals, which get about half of their food from the North Island.
Southern DHB service manager Heather Fleming said it was being cautious with its milk supply yesterday, but Compass suppliers confirmed all food would be delivered as usual today.
Lindsay Kaan, of Kaans Catering, a major supplier in the food services sector, said deliveries had been affected "like everybody else" although once the roads were open it would take about 24 hours to "catch up".
All major supermarkets reported shortages in the South.
Foodstuffs NZ head of corporate affairs Antoinette Laird said impacted items at supermarkets had included milk, produce and chilled and frozen products, as the majority of those were transported out of Christchurch.
A New World Centre City spokesman reported that while the store was getting ‘‘low’’ on milk stocks by yesterday afternoon, it had continued to make its own bread, and had managed to secure some fresh produce locally to shore it up during the break.
In addition to two additional return services between the South Island’s two largest cities, Air New Zealand will put on an additional Q300 aircraft between Wellington and Timaru and an A320 to service the Auckland to Queenstown route.
More rurally, in the midst of the critical spring mating period on most of the country's dairy farms, artificial breeding supplier LIC is using small planes and helicopters to make sure semen straws were still delivered to farmers on time.
The rail line at the Rangitata River also remains closed.
KiwiRail operations executive general manager Siva Sivapakkiam said the initial assessment was the line suffered "significant damage".
About 350m of track was affected; however, it would not be able to inspect or assess the damage properly until water levels dropped.
The line is normally used by about six services a day.
Port Otago chief executive Kevin Winders said disruption had been minimal and trains carrying goods from Port Chalmers were operating as normal.
Rain has now eased in the Otago headwaters, and Lakes Wakatipu and Wanaka have begun to recede.
Otago Regional Council duty flood officer Paul Hannah said rivers feeding into the lakes, such as the Dart and Matukituki River, remained high but were also receding.
"The forecast for the area through until Thursday 12 December is mostly clear, so the lakes should continue to steadily recede."
Modelling suggested the lakes will take 19 days from when they peaked to return to normal December levels.
MetService meteorologist Andrew James said the weather would dry up today for most of the South as a southwest flow moved over the area carrying cooler, drier air.
There could be some rain in Southland, although it was expected to be minor.
Some more rain was expected in Dunedin and further south from tomorrow, but it was not expected to be heavy.
