SRA Annual Report 2025-26: River Sowy – King’s Sedgemoor Drain Enhancements Scheme
During 2025-26, the Parrett Internal Drainage Board (IDB) completed Phase 1 of the SRA’s major £10million River Sowy – King’s Sedgemoor Drain (KSD) Enhancements Scheme. The IDB’s project team raised 1.22 miles (1.96 kilometres) of the left bank of the KSD, and upgraded Chedzoy Tilting Weir and KSD Back Ditch outfall.
These works capped a long series of improvements carried out by the Environment Agency between 2016 and 2023, such as raising another 5 miles (8 kms) of bank, desilting Parchey Bridge and the railway bridge at Dunball, creating embayments, two-stage channels and a backwater, upgrading outfalls, and replacing or repairing 100 water control structures around Moorlinch, Westmoor and at Egypt’s Clyse on King’s Sedgemoor.
These works also complemented other schemes such as the raising of the A372 at Beer Wall near Othery and the installing there of four huge culverts, two new river channels and a bespoke tilting weir; regular dredging of the River Parrett; building flood defences at Westonzoyland; upgrading Northmoor Pumping Station so it can accommodate high-capacity mobile pumps; removing a troublesome protrusion of concrete beneath the A38 bridge at Dunball; creating a pumping platform at Dunball so it too can accommodate high-capacity mobile pumps; and refurbishing Dunball Sluice.
As a result, nearly 25% more flood water can flow safely in channels through the connected River Sowy – KSD system, up from 17 cubic metres per second (called ‘cumecs’) to 21. The Sowy-KSD system runs for 13.5 miles (22km) from Monk’s Leaze Clyse sluice at Combe near Langport down to Dunball Sluice north of Bridgwater.
The Environment Agency – which is responsible for managing flood risks from main rivers such as the Parrett, Sowy and KSD – says: “All these works combine to provide a significant improvement in our capacity to manage floods, in terms of conveyance, operational response and flexibility. This reduces flood risk to the mainline railway, key roads such as the A372 and A361 and many small local roads. It increases resilience to communities frequently affected at Langport, Northmoor and Moorland and large areas of surrounding farmland.
“While we can’t say exactly how many properties or hectares of land, the scheme should provide enhanced protection to approximately 165 homes. The area of land that benefitted from the original 17 cumec operation is approximately 6,500 hectares, which could increase by approximately 1,500 hectares under the 21 cumec operation.
“The benefit also extends to managing required water levels across protected conservation sites.”
The whole system was put through an exceptionally severe test with Storm Chandra in late January 2026. This month was the second wettest since records began in 1871; one third of the month’s usual rainfall fell in two days; at its peak there was 1.2million cubic metres of water per hour coming down from the Parrett’s big catchment – about half of Somerset – through Langport.
All the improvements made were not sufficient to cope with this gigantic influx, flood waters overflowed, a Major Incident was declared and numerous pumps were brought in.
The Environment Agency did, however, gain a few more days’ extra flexibility and control at the start and the end of this major incident and this did help to reduce flooding. Because, the more water can safely flow from the Parrett into the Sowy, the less water there is in the Parrett. The less water there is in the Parrett, the more water can be pumped off moors into the Parrett. So the Environment Agency say that water was off land about a week earlier than it would otherwise have been.