An oil leak from a power station at Avatiu on the Cook Islands main island of Rarotonga is being blamed on heavy rainfall.
People living in the Avatiu Valley last week complained of the strong odours and residue leaking from the Te Aponga Uira power station.
They say there had been a strong stench of diesel in the area and slicks of diesel could be seen in the Avatiu stream below the power station.
Te Aponga Uira chief executive, Apii Timoti, says a waste oil septic tank had overflowed, dumping some of its contents into the neighbouring stream.
He says an overwhelming volume of rainwater had caused the tank to flood.
Two reports going back four years have called for extensive repairs to the storage tanks.