A state of emergency was declared in Westland at 5.45pm following severe weather which has attacked the region since Sunday.
Torrential rain and strong winds have battered the South Island region, forcing emergency services to close roads and evacuate members of the public.
Earlier this evening, the Waiho Bridge was taken out by rising and rough floodwaters of the Waiho River near Franz Josef.
The river was running at a level of 7.6m but has dropped back 0.7m from its peak.
Elsewhere, the Haast River neared a high-level mark but levelled off at 7.6m. However, the Hokitika River continues to rise, sitting at 5m around 7pm.
Westland Mayor Bruce Smith told Newstalk ZB heavy rain was at the base of their problems but people remain the focus of the council and Civil Defence.
"I called a state of emergency, the reason for that is that we've lost the Waiho Bridge at Franz Josef, it's been demolished," Smith said.
"This is a 100-year event, there is a huge amount of rain … I haven't seen all of the rivers impacted in Westland at exactly the same time," he said.
The South Island's road network has taken a hammering due to the heavy rain and strong winds which have resulted in flooding and slips.
The main highway connecting Otago with the West Coast is closed from Makarora to south of Hokitika.
The NZTA extended the closure of State Highway 6 just after 1pm, after it was closed between Franz Josef and Fox Glaciers earlier this morning when two slips covered the road.
“State Highway 6 is currently closed south of Hokitika," said NZTA Network Manager Colin Hey this afternoon.
"Given the bridge is now gone on one side, this closure will continue until the bridge and its abutment can be safely replaced.”
Flooding has also closed the Wanaka-Mt Aspiring road, and Kinloch Rd in the Queenstown Lakes District.
The rain has also closed a second key highway to the West Coast this afternoon.
SH73, the Arthur’s Pass/Otira route is closed at at Candys Creek owing to a slip.
It will be reassessed on Wednesday morning with an update around 8am.
Farmers on the south side of the Waiho River have already started to self-evacuate but the rising river was causing further headaches, Smith said.
An Emergency Coordination Centre has been set up at the West Coast Regional Council in Greymouth.
The ECC will further assess the need for a controlled evacuation on the south side of the Waiho River, the Westland District Council said in a statement.
"There has been minor breaches from the Haast River into some properties, and accordingly a Welfare Centre has been opened in the Haast Hall," it reads.
"Displaced persons are advised to go to the Welfare Centre in the Haast Hall for assistance."
Ritchies have suspended all bus services tomorrow for the West Coast.
Rainfall is expected to ease from South Westland from midnight, Civil Defence West Coast said.
"As the front moves north heavy rain is expected to impact on river levels and roading networks," Civil Defence said in a statement.
"River levels are currently being monitored throughout the region, with the Waiho and Hokitika Rivers currently elevated."
Smith said heavy rain was expected to continue for another eight hours but it would ease before tomorrow morning.
Following the loss of the Waiho Bridge, the entire Westland region's tourism industry would be impacted.
"The loss of the Waiho Bridge is a real problem for tourism on the West Coast and for tourism in South Westland and Hokitika in particular," he said.
The South Island's road network has taken a hammering due to the heavy rain and strong winds which have resulted in flooding and slips.
The NZ Transport Agency asks motorists to take extra care with the extreme weather, debris and flooding impacting sections of road.
Localised flooding on the South Turnbull Rd in Okuru and south of the Arawhata Bridge has resulted in self-evacuations south of the bridge.
MetService reports a strong and moist northwest flow covering the South Island ahead of an active front over the Tasman Sea is to blame for the weather.
In addition, heavy rain warnings are also in place for Buller, northern Westland and the north Canterbury headwaters.
MetService said the strong front will slide over the South Island today before breaking on to the North Island tomorrow, bringing with it strong winds and heavy rain.
Haast resident Kerry Eggeling earlier said rain in the area in the past 24 hours had led to a couple of buildings at the Waiatoto River to be flooded, but he believed the worst of the storm was over.
Most of the rain had fallen in the hills towards the Haast Pass, he said, and the rain on the front country was nothing to be concerned about.
"The tide is on its way in now, but I believe the biggest part of the rain has gone. As the tide rises now, the rivers will drop, so there won’t be much change in the water levels.
"As soon as it stops raining in the hills, it doesn’t take long for the rivers to drop because its such a short distance from the mountains to the sea, so it doesn’t take long for the water to run out."
- By Sean Nugent, John Lewis and NZME
