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 areas. When heavy rainfall is predicted, the canal can respond by lowering its levels by up to four inches over a 20-mile stretch of the canal in Glasgow.

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

The Lock 21 project is partially funded by Scottish Water (£630,000) and partially by Scottish Canal’s Capital Investment Fund, which is our funding from Scottish Government to maintain our canal infrastructure.

The lock bypass will give us better control over water levels in the canal, offering an alternative route for water around the lock. Meanwhile, we will install kiosks (small metal boxes) containing the telemetry technologies that enable the smart canal’s autonomy.

Upcoming project activities

In June 2026, 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. A towpath diversion will be in place along Maryhill locks from Monday 1st June to Friday 5th June. 

Maryhill locks have high historical interest as well and we are working with Historic Environment Scotland (HES) to log archaeological finds throughout the works and ensure we safeguard important features of interest. 

During the works to repair the Kelvin Aqueduct, we discovered a series of wooden fenders in a grid pattern dating from the canal’s construction in the eighteenth century. At Lock 21, you can see the remains of a wooden flood gate, which was designed to be deployed in heavy weather to prevent surges of water travelling along the canal. The gate is likely original so dates from circa 1790.

We have also conducted 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.

Work on site to construct the bypass will begin this winter (2026/2027) and we will provide more details of the project’s scope and timelines nearer the time. 

Mackenzie Construction will also investigate a potential pipe route on land above the Kelvin Walkway for a future renewable energy scheme, using funding provided by the active travel charity Walk Wheel Cycle Trust. This second project is at early feasibility stage but in essence would utilise water from the Forth and Clyde to power an underwater turbine. The energy produced would then be exported to the National Grid.

We will provide more information on this project as it develops and its feasibility is further assessed. 

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).