Trade through Runcorn began to slow towards the end of the 19th century and by the turn of the century use of the locks was in terminal decline. The old line was disused by the late 1930’s and were closed and filled in under the Ship Canal Act 1949.
The new line of locks carried on operating a little longer but they could not survive. The Ship Canal Act of 1966 allowed their closure and they were filled in shortly after.
The materials used to fill the locks was not well controlled. There are anecdotal stories of fridges, car tyres and numerous nasty chemicals. In the mid 1970’s the Silver Jubilee Bridge was widened from 3 lanes (yes 3 lanes – one either way and an overtaking lane in the middle!) to two lanes in each direction. At this time new approach roads were built connecting to the newly built dual carriageways circulating the town. It is this construction that built over the upper locks and made reconnecting the Bridgewater and Manchester Ship Canals impossible – at least temporarily.
At this time much of the contaminated infill was removed from the upper locks and refilled with clean material. An overflow drain was also installed down the new line to take excess water from the Bridgewater Canal down to the MSC.
In 1989 contaminated infill from the old line was also removed and replaced with clean material. The route of the old line was largely maintained and has been turned into a pedestrian walkway. Many of the original features of the old line can still be seen to this day.
