The Leeds and Liverpool Canal is set to be drained at one lock in Chorley.
The canal at Wheelton, to the north east of the town, will be emptied at Lock 59 to replace two gates that have become split and rotten.
The gates are roughly 100 metres from the Top Lock Pub in Copthurst Lane.
The rot has resulted in in "excessive leakage" at gateposts, the Canal and River Trust notes, with the life expectancy of the tail gate rated at less than three years.
And while the head gates have been given a life expectancy of less than a decade, the Trust notes that "is it considered sensible and economic to replace them while staff are on site replacing the tail gates".
The gates themselves are more than 25 years old and have also been damaged by boats impacting them.
Work is set to start in January 2020 and last for six weeks.
The lock, known as Lock 59 on the Trust's grid of the canal, is on the Johnson's Hillock flight of seven locks.
The Trust is also set to reinstate and extend a ladder into the canal, which was removed for repair but not brought back.
"The recess for the ladder currently extends below the lowest water level but not far enough to meet the standard," the Trust writes.
The Trust has applied to Chorley Council to gain permission for the change due to the lock being Grade II listed by Historic England.
A spokesman for the Trust said: "The work at Lock 59 is to replace both sets of lock gates - head and tail - and also to replace the footbridge, so it is quite a big job.
"The work will start in January and last around six weeks."
The new gates will be made at the Canal & River Trust’s workshop at Stanley Ferry in Yorkshire.
While it is not yet known the points at which the canal will be drained, it is understood this will be decided over the next few weeks.