New flood defence gates in Truro, Cornwall are now fully operational, securing the city's flood defences for the next 30 years - 185 properties in Truro are now protected by the newly replaced flood defence gates.

The newly refurbished tidal barrier forms a critical part of Truro’s comprehensive flood risk management system working alongside the Idless and New Mills Dams to reduce risk to commercial and residential properties in the city centre.

The ambitious engineering project by the EA’s construction partner Kier began in April 2024 and involved replacing existing gates that had reached the end of their serviceable life. The new gates were successfully installed in August 2024 using a 400-tonne crane during a carefully planned operation that coincided with spring tides to ensure optimal working conditions.

Emergency planning proves effective

During construction, the project’s robust emergency planning was put to the test when tidal surges exceeded forecasts. Temporary flood barriers called stoplogs were deployed for the first time at Truro, successfully protecting the city from flooding and demonstrating the effectiveness of the Environment Agency’s flood protection planning.

The gates are designed to be closed during high spring tide and storm surges, providing reliable protection that will operate effectively for decades to come.

Gates are ‘more efficient and reliable’

Andrew Houghton, operations manager at the Environment Agency, said:

“This project represents a significant investment in Truro’s flood resilience. The barrier and its controls are more reliable, meaning we can ensure effective flood risk management for the community into the future.”

Philip Ramsay, operations director for Kier Natural Resources, Nuclear & Networks, added:

“The whole team is proud to have been part of the refurbishment of this vital Cornish flood risk management scheme. We’ve applied innovative techniques and experience from other sectors to make these gates more efficient and reliable.”

Reservoir upgrades to hold flood water nearly finished

Completion of the tidal barrier work is scheduled for the end of October 2025, marking a significant milestone in protecting Truro from the increasing flood risks posed by climate change.

Beyond the new tidal barrier, the Environment Agency is enhancing flood protection across Truro through coordinated improvements to the city’s reservoir infrastructure.

At Idless Flood Storage Reservoir on the River Allen, vital upgrades to improve the dam’s resilience during severe weather are nearing completion. These improvements will ensure the reservoir continues to provide reliable flood protection when extreme conditions put infrastructure under greatest pressure. The enhanced system will be fully operational by December 2025.

Emergency pump test exercise was a success

Meanwhile, rigorous testing of emergency procedures has strengthened preparedness across the network. In July 2025, specialist Environment Agency teams successfully conducted a major exercise at New Mills Dam flood storage reservoir, demonstrating their ability to rapidly reduce water levels using high volume pumps. A follow-up desktop exercise in September 2025 completed comprehensive training that ensures compliance with reservoir safety legislation and establishes best practice procedures for similar operations nationwide.

Together, the three flood risk assets – the new Truro tidal barrier, the upgraded Idless reservoir, and the operationally-tested New Mills Dam – provide multiple layers of protection that will safeguard Truro against flooding for decades to come.

The Environment Agency are working on a flood risk strategy for Truro to manage the resilience to future flood risks in the city. The strategy is considering climate change impacts, including rising sea levels, increasing river flows and increased rainfall intensity leading to more frequent surface water flooding. This work is being undertaken in partnership with Cornwall Council.

WaterBriefing is supporting the upcoming Floodex & National Drainage Show which takes place in London on 26 – 27 November 2025 in London. Now in its tenth year, Floodex will run alongside the National Civils Show, opening the event up to whole new audience of thousands of interested civil engineers, contractors, developers and planners, involved in construction, utilities, highways, railway and coastal defence professionals.

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