A partnership between the Severn Rivers Trust (SRT) and the Environment Agency (EA) in Worcestershire and the Black Country has enabled the formation of a conservation project within the River Stour catchment. The River Stour is a semi-urban, semi-rural catchment linking Clent Hills, the Black Country, Staffordshire and North Worcestershire via 26 miles of watercourse and is a major tributary to the River Severn.
Covering 374.66km2 which includes urban areas of heavy industry in the Black Country and sandstone-rich rural farmland, the Stour contributes large quantities of nutrients and contaminants to the River Severn. The Black Country section of the Stour contains approximately 11 remaining weirs that are major barriers to fish migration, a major issue in a catchment that has historically been a salmonid spawning ground. Most of these were installed during the 17th and 18th centuries to power iron-works, cereal mills, wool mills etc, and have long since been forgotten and left to deteriorate.
This project has a long-term vision to aid fish migration through the Stour Catchment and improve overall water quality to achieve Good Ecological Status under the Water Framework Directive (Directive 2000/60/EC: WFD). Starting at a small scale in the first year (july 2016 – March 2017) with a number of easy-win implementations and building in the second year to better gauge and encourage public interest, with the foresight of a large funding bid for a catchment-scale restoration project.
With the resources available within Year 1, it was decided that barriers to fish migration within the Stour should be the focus of work on the ground. Through site visits, land-owner contact and desk studies, 11 weirs were prioritised on the basis of time available, accessibility, cost benefit and environmental benefit.
Through these criteria, one weir in the middle of the catchment at Prestwood was chosen for works to be implemented upon to improve fish migration by the end of Year 1. Weir number 3467 on the map below.
Conditions here were suitable for a small-scale project that would easily improve fish passage over the barrier and would be within the project budget. This weir was chosen as it is small and easily accessible. The total budget of £20,000 would include a full bathymetric and topographic survey of the site as well as the physical works to the weir.
Through the survey results, consultation with the landowner and contractors, the decision was made to create a notch in the centre of the weir that encompassed ~40% of the total width of the weir. This would allow enough space and flow for effective fish passage over the weir. The notch would be made to bed-level, a depth of ~1m.
To increase flood capacity and reduce bank erosion up and downstream of the weir, the SRT and EA agreed with the landowner that the banks would be graded back to a 1-in-3 or ~45° and planted with native grass seeds and a variety of native trees. The existing electric fence would then be pulled back and relocated to the top of the newly graded bank to prevent erosion from cattle.