The United Nations has been forced to apologise after the River Mersey was deemed unfit to sustain marine life.
More than £1bn has been spent on cleaning up the river
Environmentalists were confused as to why the Mersey estuary had been added to the UN list of "dead zones".
In the 1970s it was the dirtiest river in Europe, but now it has been cleaned up and porpoises, dolphins, seals and even salmon have made it their home.
UN researchers have now admitted they were using out-of-date information and have taken the Mersey off the list.
Marine dead zones are areas where low levels of oxygen in the water make it difficult for fish and other marine life to survive.
The areas have been tracked globally since the 1970s and have increased every decade.
Harbour porpoises and even salmon have been spotted
The error was spotted by Wirral environment expert Dr Peter Jones, a scientist at the Environment Agency.
He wrote to the researchers saying that over the past 15 years, more than £1bn had been spent by United Utilities to improve the water and that the estuary now supported an increasing variety of fish.
The researchers have now confirmed that the Mersey should never have been on the list that was released.