A vessel sunk to the bottom of the North Quay at Haysham harbour after starting to take in water on Sunday morning
The vessel, Abigail H, sunk to the bottom of the North Quay at Heysham harbour, Lancashire, after it starting to take in water on Sunday morning.
The 35 metre long vessel started to leak the fuel - but emergency services contained the spillage.
The dredger sailed into the dock on Saturday and reports suggest it may have been damaged when it sailed into the bay.
Fire-fighters and officers from the Environment Agency were on the scene yesterday morning and with the Coastguard Agency and Lancashire Fire and Rescue Service, were able to contain the oil spillage in the bay.
The 160-tonne dredger - which is used to clear the harbour to ensure the safety of ships passing through - had initially been moored at Heysham Harbour's North Quay.
Three crew were on board when she began taking in water in the early hours of Sunday.
A spokesman for HM Coastguard said, "she is in a tidal area which is making pumping attempts difficult. She sank pretty quickly and now we are faced with an anti pollution battle.
"All the crew got off her safely. But there was some minor spillage, but it has been contained. The owners and the insures are now at the scene evaluating the damage."
A spokesman from Lancashire Fire and Rescue Service said: "We left the site at about midday and now the salvage operation has begun."