Eight abandoned vehicles have been discovered during the clean-up on the Somerset Levels.
It is thought some of the cars in the King's Sedgemoor Drain, near Bridgwater, could have been there up to 20 years.
Environment Agency (EA) staff spotted the cars in the flood drainage channel last week after water levels were significantly reduced.
The water channel is used to help drain the surrounding peat moors and is intended to bring some relief from flooding in the area.
The cars, which include a Ford Escort, Ford Fiesta and Vauxhall Cavalier, were found within around 100 metres of each other but it is not known exactly how they got there.
When they were removed on Wednesday by contractors several healthy eels were found inside, which were "literally crawling out", the EA said.
Officials said the vehicles would not have affected the recent flooding, which devastated many communities in Somerset.
John Rowlands, from the Environment Agency, said: "Some of them are over 20 years old, they certainly would not pass a MOT, and they range from a Ford Escort, to a Ford Fiesta and a Vauxhall Cavalier.
"The area around where the cars were located has a car parking area, there is an access track there; so it is easily accessible should somebody want to do something underhand with a vehicle."
An EA spokesman added: "We have been keeping the water levels on the King's Sedgmoor Drain at a record low and this led to the cars being exposed.
"They posed an environmental risk and have now been removed thanks to a skilled team of divers and winch operators."
The police have been informed, who will attempt to identify the owners, before the cars are disposed of.