Weston Marsh Lock has been de-watered as part of a 1/2 Million Pound Inspection and maintenance works programme, including refurbishment of lock gates and mechanical components.
Other works also include paddle repairs and stop plank groove replacements.
It is over half a century since the last time it was drained.
The lock came into operation when the Manchester Ship Canal was opened in 1894. As the tidal section of the river below Frodsham now flowed into the ship canal, rather than the River Mersey, this new ship lock was constructed at Weston Marsh, and provided a more convenient route to the ship canal than the original route through Weston Point docks.