The river in Louth is swollen after days of rain.
The Environment Agency say there is no flood alert for areas near the River Lud, including Broadbank and Ramsgate Road.
However they say there is a flood alert for the Louth Canal from Louth to Tetney Lock, the Waithe Beck from Binbrook to Tetney Lock and their tributaries, including the River Lud in Louth.
The say tributaries may also affect Utterby and Covenham St Mary.
A flood alert means flooding is possible and people should be prepared.
The next levels of warning from the Environment Agency are flood warning and then severe flood warning.