Mobile Oil has escaped prosecution after the Canterbury Regional Council decided not to press charges over a spill that caused 1500 litres of diesel to contaminate water in the Lyttleton Harbour.
The spill was caused when a holding tank at the South Island port was damaged by a landslide in March this year.
The council's chief executive, Bill Bayfield, said today that a prosecution for the discharge of contaminants into the harbour had little chance of success, so it was not in the public interest to pursue it.
Mr Bayfield said it was difficult for the company to have predicted or prevented the incident, which was caused by a combination of earthquakes, flooding, erosion and the proximity of the tank farm to a steep hill.
There was no proof of negligence, he said.