Twizel Mill Cauld removal, United Kingdom

Introduction

Twizel Cauld is situated on the River Till in the Tweed Catchment, just upstream of the A698 road bridge, northeast of Cornhill-on-Tweed. The River Till flows in a north-westerly direction from its source in Comb Fell in the Cheviot Hills, joining the River Tweed approximately 3 km downstream of Twizel Cauld.

The River Tweed then flows in a north-easterly direction before reaching the sea at Berwick-upon-Tweed. The River Till is the only major tributary of the River Tweed that is located entirely within England.

Project context and opportunity

Following concerns over the impact of the weir on fish passage, an assessment was undertaken by Fishtek Consulting Ltd in 2021. The assessment found that the structure did not comply with current best practice for pool and weir fish passage due to insufficient depth (within the pools and beneath the most downstream notch), excessive head drop, and the short length of the second pool of the pass.

Project aims

The River Till Catchment is classified as a Site of Special Scientific Interest (SSSI; ID 1006740) and forms part of the broader Tweed Catchment Rivers SSSI group and the River Tweed Special Area of Conservation (SAC; Code UK0012691). Removing the weir will enhance the biological connectivity of the River Till, both longitudinally (downstream) and laterally (channel-floodplain connectivity).