There are fears of an oil spill in Milford Sound following an accident in Freshwater Basin this afternoon.
A crane mounted on a barge fell on its side, leaving the body of the crane on the barge and part of the boom resting on a pile.
There is understood to be 200 litres of diesel and 24 litres of engine oil in the crane, along with 1600 litres of hydraulic oil in a power pack on the barge.
"If that all spills, there will be a very obvious sheen in the water," Environment Southland Regional On-Scene Commander Dallas Bradley said.
"Our priority is to prevent it spilling at all. However, we have to wait for an Occupational Safety and Health inspector to assess the site before we can look at trying to remove the oil and fuel."
Booms have already been set out around the barge in case any of the oil on board spills and more equipment and staff have been dispatched from Bluff and Invercargill.
Mr Bradley said the situation was considered stable.
