SRA Annual Report 2022-23: River Sowy – King’s Sedgemoor Drain enhancements scheme (Phase 1)
For several years the SRA has funded extensive improvements to the River Sowy (Parrett Flood Relief Channel) – King’s Sedgemoor Drain (KSD) system. The main aim has been to increase the amount of water that can flow, in a controlled way, from the Parrett into the Sowy through Monk’s Leaze Clyse sluice near Langport, down to the KSD near Greylake, then back into the Parrett through Dunball Sluice north of Bridgwater. SRA partners have also needed to ensure that legally- protected wetlands of international importance are not made less wet, through more water being kept in river channels, and some moves have been made to improve habitats and to upgrade water level management control structures.
In 2021 and 2022 the Environment Agency, as a partner in the SRA, employed contractors Kier to raise banks so that more water could be kept in channel and not overtop. For environmental reasons, bank-raising works have largely had to be carried out in August, September and October. In 2021, 1.32 kilometres (0.82 miles) of the right bank of the lower Sowy was raised, between the A372 at Beer Wall and Sandy Lane near the A361, that was 21% per cent of the total length required along both banks of the Sowy. Seven ecological enhancements were completed. Progress was slowed by the coronavirus pandemic, wet weather, and particularly a shortage of skilled excavator drivers.
In 2022, further Sowy and KSD bank-raising was hampered by an unfortunate combination of very dry and then very wet weather. Firstly, summer and autumn drought conditions caused newly-constructed banks to shrink much more than expected, and some material was too dry to build banks with. Downpours from mid-October then made it extremely difficult to work with heavy plant on soft wet peaty ground. Nevertheless, with the help of a special extension granted for the continuation of works into November by Natural England, by the end of November the Sowy’s left and right banks were raised where necessary, the KSD’s right bank was raised where required down to Parchey Bridge, and progress was made along the KSD’s left bank.
Outfall structures were modified on two KSD side streams (Cossington Right Rhyne and Chilton Right Rhyne) and Parchey tilting weir installation works began in March 2023 (and were completed in May 2023).
Bank-raising works remain to be done along up to 1.8km of the left bank of the KSD. Three outfall structures also need to be upgraded (Level Rhyne, KSD Back Ditch, Chedzoy Tilting Weir). In March 2023, SRA Board members approved additional funding for these outfall works, and agreed that all SRA partners should work together to get the KSD left bank works finished. Ways of completing this job as cost-effectively as possible are being explored.