The Environment Agency has completed a £9.7 million upgrade of the Dunball Sluice on Somerset Levels – the sluice performs a vital flood and water management function on the Somerset Levels and Moors.

Photo: aerial view of Dunball Sluice early refurbishment work

The upgrade has given the sluice, which became operational in 1971, another 25 years of operational life, helping to better protect properties, businesses and internationally important habitats across the Somerset Levels and Moors. 

Delivered by the Environment Agency’s Combined Delivery Framework (CDF) partners, the refurbishment began in 2022 and was funded by the Department for Environment, Food and Rural Affairs (Defra), with a £650,000 contribution from the Somerset Rivers Authority (SRA). 

Dunball Sluice sits where the tidal River Parrett meets the 13.5-mile-long King’s Sedgemoor Drain - River Sowy system. The Sowy was created in tandem with the Sluice in 1969-1972: it is also known as the Parrett Flood Relief Channel. Water flows into the Sowy from the Parrett downstream of Langport, and then into the KSD, before rejoining the Parrett through Dunball Sluice. 

The Environment Agency uses the sluice’s lifting gates and tidal flaps to control flows between the different watercourses. Doing this helps to manage water levels and reduce flood risks for communities across a large area. Blocking the flow of tidal saltwater from the Parrett into the KSD also helps to safeguard precious freshwater habitats on the Somerset Levels and Moors.  

The refurbishment replaced and upgraded key mechanical, electrical, instrumentation, control and automation components, many of which were nearing the end of their working life.

Also included were measures to help otters and eels move more easily and safely between watercourses, health and safety improvements for site staff and minor concrete repairs. 

‘New life breathed into the structure’

Rachel Burden, Environment Agency flood and coastal risk manager for Wessex, said:   

Dunball Sluice is one of Somerset’s most important tidal defence assets, but many of its key components were reaching the end of their working life.

This multi-million-pound refurbishment has breathed new life into the structure, ensuring it can continue to reduce flood risk for communities for years to come.

Councillor Mike Stanton, Chair of Somerset Rivers Authority (SRA), said: 

“Maintenance and improvement works are not glamorous, but they are very important. Local people expect flood defences to work properly, and all of us should try to make sure they do.

“This project ties in with a major SRA improvements scheme for other parts of the River Sowy-KSD system. This year the SRA is funding upgrades for two outfall structures and up to 1.8 kilometres of bank raising works along the KSD.”