Lock 21 (Maryhill) Bypass Installation on the Forth & Clyde Canal

Scottish Canals continues to evolve the Glasgow Smart Canal – one of the first examples in the world of a canal being used as an urban sponge. 

The Forth & Clyde Canal has the ability to lower its water level automatically in response to weather forecasts, providing capacity to soak up surface water run-off from canalside communities. When heavy rainfall is predicted, the canal can respond by lowering its levels by up to four inches over a 20-mile stretch. 

The result is a canal that contributes to climate change mitigation in Scotland’s Central Belt. It has also freed up disused, brownfield sites for housing, which would otherwise have insufficient drainage, (3,500 new houses are built or in the pipeline as a result in North Glasgow).

How does the lock bypass at Maryhill fit in?

Installing bypasses at locks 20 and 21 is essential to ensuring that the canal can cope with additional incoming flows of water further downstream of the two locks when the smart canal is in operation (anticipating the upcoming housing developments along the canal).

A similar bypass was installed over the winter of 2024/2025 at Lock 20.

• Find more information about this earlier project
• Discover more about lock bypasses

Upcoming project activities

In summer 2025, our contractor Mackenzie Construction will commence surveys of the ground conditions (using trial pits) around the lock and will identify any underground utilities along possible bypass routes. We will also conduct ecology surveys to understand the presence of mammals in the area, as well as planning the fish screening that would be needed for the project.

We will provide updates about the survey dates and the start of construction activity at the site nearer to the time. If you have any questions or concerns, please contact us at enquiries@scottishcanals.co.uk or on 0141 332 6936 (Monday to Thursday 8.30am-5pm, Friday 8.30am - 4.30pm).