Case Study
River Ash Weir By-pass, Surrey
Location
Shepperton, Surrey
Date
May - August 2016
Client
Spelthorne Borough Council
Stakeholders
Environment Agency
Tasks
- Remove section of weir to allow multi-species fish passage in all flow conditions
- Design and installation of flow control structure into online lake to consolidate low flows in by-pass channel
- Re-grading of 600m by-pass channel to increase in channel and riparian habitat
- Installation of gravels
- Installation of woody material
- Pre-restoration fish and macroinvertebrate survey
- Installation of hibernaculums
Key remarks
- Pre-restoration surveys found poor fish and macroinvertebrate communities
- Flexible approach to design using a toolbox of approved features allowed us to get the best possible results on site
- A good case study to show low cost methods to improve degraded urban rivers using site won materials
Effects
- Multi-species fish passage at all flow conditions
- Creation of gravel spawning habitat in otherwise degraded reach of the River Ash
- Channel opened up to improve engagement with the river corridor
