Police are urging evacuated residents not to return to their homes in Wainfleet.
More than 80 homes were flooded and many more avacuated when the River Steeping burst its banks.
RAF helicopters have dropped 100 tonnes of sand and ballast to surging waters in the past 24 hours to plug the breach in the River Steeping.
It was hoped the breach would be plugged by 6pm, and it is understood water levels are improving but Lincolnshire Police have warned it is still not safe for residents to return to their homes.
A statement reads: "We've been asked to emphasise to those in Wainfleet who have had to leave their homes that it is still not safe to return yet.
"Although it is hoped the breach in the river bank will be plugged by 6pm, there will still be work to be done to make the area safe and updates will be given tomorrow when it is felt safe to return."