A major repair and maintenance project is necessary on the lock gates which maintain water levels in Sutton Harbour

A major repair and maintenance project is necessary on the lock gates which maintain water levels in Sutton Harbour and form a key part of Plymouth’s coastal defences, protecting hundreds of homes and businesses in the Sutton Harbour and Barbican area of the city. 

The £3 million project is being carried out by the Environment Agency in collaboration with the Sutton Harbour Company, with funding from the UK Government, and will see the replacement of worn lock gate cills and other key maintenance items.

This will ensure the effectiveness of the tidal barrage for another decade.

Work on the lock gates is expected to commence in 2023.

harbour operations during The Project

Sutton Harbour Company, which is the statutory harbour authority, and which operates the lock, Plymouth Fisheries and Sutton Harbour Marina, is working in close collaboration and partnership with the Environment Agency and Kier, its selected contractor, in planning for the project and how operations and access will be maintained in the harbour.

The aim is to minimise disruption for harbour users during these essential works and to put in place mitigation measures where necessary, in particular working closely with and supporting the continued operation of Plymouth’s fishing fleet, including access to landing, berthing, fuel and ice facilities.

This website has been created by the project partners as an information portal for the project and is intended as a resource for all harbour users, local businesses, members of the public and anyone with an interest in the harbour.

More detailed information will be added in advance of the start of work and will be updated throughout the project on the timetable of work, daily access arrangements to the harbour and mitigation measures

Frequently Asked Questions

Regular maintenance will always be necessary for structures such as the lock, operating in challenging coastal environments. The gate seals at the bottom of the lock gates at Sutton Harbour have deteriorated to the point of potential failure and therefore require these works to repair and replace the bottom gate seals to ensure the water can be maintained in the harbour and for flood protection to be maintained to the surrounding area.

This project involves replacing the existing four gate seal assemblies which are fixed to the bed of the lock, below the tidal gates at Sutton Harbour. As well as this, the adjacent stop logs across the original harbour entrance and the pedestrian walkway over the stop logs will also be replaced.

The tidal gates are a key part of Plymouth’s coastal flood defences. Were they to fail this would pose a flood risk to the Sutton Harbour and Barbican area with more than 500 properties at risk. Moreover, vessels within the harbour would be at risk of grounding out as the harbour would no longer have the minimum maintained water level and would be subject to tidal movements.

The project will help to maintain flood protection and ensure the functionality and viability of the tidal lock gate for another decade.

Work on the lock gates will commence in 2023. The Sutton Harbour Company, with participation by the EA and its contractors, will lead a consultation process with harbour users, including the fishing fleet and berth holders to determine a start date. The full schedule of work is expected to take around seven months to complete, based on the current programme, although for clarity, it is emphasised that not all of the work affects normal operation of the lock gates. Full timetables of the works and lock opening and closings will be published in due course. The works are planned to be completed prior to April 2024, to minimise the increased risk for failed cills beyond that point, and fully utilise the project funds available until that date.  

The major part of the project is the repair and replacement of the four lock gate seals which will be carried out underwater by a team of specialist divers. They will be assisted by a shore-based support team and construction team carrying out elements of the project accessible from the quaysides.

This project aims to provide new gate seals which will ensure the effectiveness of the tidal barrage for another decade.

Current projected figures estimate the total value to be approximately £3million.

The works are being funded by UK Government through the Environment Agency Flood Defence Grant in Aid and participation by Sutton Harbour Company as agreed by the parties. Funding for the project has been secured and is available for application to the project through April 2024.


The project is being managed by the Environment Agency.

The over-riding objective is to minimise disruption to harbour users as much as possible. Working groups are being established with key harbour users including the fishing fleet and berth holders. These groups will inform the project in finding an optimum time for the work to be carried out, and in drawing up mitigation measures where necessary in collaboration with the Sutton Harbour Company.

The pedestrian footbridge will remain in operation during the project. The existing walkway over the stop logs is to be replaced which will mean pedestrian access will not be possible for a few days. There will also be other periods when temporary limits on access are required to allow work to be undertaken without putting the safety of members of the public at risk. Any closures will be widely publicised in advance and during these periods pedestrian access to the east side of the harbour will be via the existing waterfront trail.


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Contact Us

Please contact the below addresses with any queries:

Lock gates project management:


Harbour management and access; Plymouth Fisheries and marina operations: