Gore District Council fears a 50m section of bridge over the Mataura River knocked out by floodwaters is being washed down stream and have urged people to keep clear.
A Gore District Council spokesperson said this afternoon ''flood waters have taken out Pyramid Bridge'' which crosses the Mataura River near Riversdale.
The council is urging people to stay away from the river and any structures in the path of the debris.
There had been a build up of debris at the bridge today, due to the high water flow following yesterday's heavy rainfall.
In an update after 2pm the spokesperson said council roading and three waters teams were on site and focused on the safety of motorists and people in the area and water supply for residents and livestock on the Otama rural water supply scheme.
The council had not located where the section of bridge had been swept to and there were fears it could be travelling down stream, although given its weight it could have sunk to the river bed.
"We are advising people to stay away from any structures downstream of the bridge in case the debris is heading downstream."
The advice came amid reports "a lot of bystanders" were at the site to witness the damage.
The main pipe for the Otama rural water supply scheme, which was attached to the bridge, was severed as it was swept away and the council was looking at bringing in a tanker to provide clean drinking water and at options to restore supply.
There were 253 connections to the scheme for stock and household water.
A reporter at the scene said engineers from Opus arrived at the scene just before 2.45pm.
Riversdale-Pyramid Rd leading up to the bridge had been flooded and was blocked off to traffic with hay bales.
River levels were continuing to rise in some areas of Southland, but not to flood level at this stage, Emergency Management Southland boss Angus McKay told Stuff.
