Case study:Ennerdale Mill Weir Removal
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- 1 Project overview
- 2 Image gallery
- 3 Catchment and subcatchment
- 4 Site
- 5 Project background
- 6 Reasons for river restoration
- 7 Measures
- 8 Monitoring
- 9 Additional documents and videos
- 10 Additional links and references
- 11 Supplementary Information
|Project web site||http://westcumbriariverstrust.org/projects/ennerdale-mill-weir-removal|
|Themes||Environmental flows and water resources, Fisheries, Habitat and biodiversity, Hydromorphology, Urban|
|Main contact forename||Luke|
|Main contact surname||Bryant|
|Main contact user ID||User:WCRT|
|Contact organisation||West Cumbria Rivers Trust|
|Contact organisation web site||http://www.westcumbriariverstrust.org|
|Partner organisations||Natural England & Environment Agency|
|Parent multi-site project|
| This is a parent project
encompassing the following
Ennerdale Mill Weir, located on the River Ehen in Egremont (Grid Ref NY 012099) dates back over 250 years and was constructed to power the Ennerdale Paper Mill. The Weir has not been used as it was intended for many years and has been proven to be a barrier to migratory species of fish in the Ehen catchment, as well as a crucial site for Freshwater Mussels.
A consortium of funders- WCRT, the Environment Agency, Natural England, the European Maritime and Fisheries Fund and James Fisher Nuclear- have combined resources to enable this weir removal project to take place over the summer of 2018. The project was delivered as part of the Cumbria River Restoration Strategy, a partnership between the EA, NE and WCRT.
In June 2018, we mobilized to site to begin the delicate task of removing the weir, without causing ecological damage through the uncontrolled release of silt and sediment into the river system. A specialized contractor, Ebsford Environmental, were chosen to deliver the works, ensuring silt control measures were installed downstream of the weir. In addition, prior to the works, WCRT and Natural England conducted a translocation of freshwater mussels from within the work site, re-locating 48 mussels upstream of Egremont.
The working methodology, developed by WCRT and AECOM, involved river bank re-profiling, berm lowering, re-grading of the existing riverbed & installation of toe protection (boulders that reinforce the river bank to provide protection against erosion), all conducted in a specific order to minimise sediment disturbance. Once the preparation was complete (approx. 4 weeks) we were ready to ‘notch’ the weir which lowered the water levels upstream, allowing the sediment & gravels that had built up over decades to be removed in the dry. Removing the weir structure itself took one week, and throughout that process Durham University were conducting heritage recording of the site so that we have a historic record of the structure of the weir.
With the weir structure removed, the final tasks were to re-profile the riverbed and rapids upstream and downstream, and further strengthen the river banks with stone protection.
Works completely finished on 31st July 2018, meaning the whole project was delivered in around 7 weeks.
The Rivers Trust and the Environment Agency, supported by other partners, have been working with the Marine Management Organisation and Defra to develop a coordinated and funded programme of projects for 2018/19 with the aim of freeing migration routes of barriers to fish.This project is part of that programme funded by over £1.6 million of European Maritime and Fisheries Funds, which is matched by more than £1 million of Agency/Defra funding and £300,000 of other funds.
Monitoring surveys and results
Durham University undertook Archaeological Monitoring in 2017 and during the removal in 2018
Immediately post-removal WCRT have been conducting regular fixed-point photography across the site, to highlight how the river adapts and responds to being re-naturalised.
Drone-captured aerial imagery has also been recorded post-removal; once collated this can be contrasted with the footage captured pre-removal for before-and-after analysis
Catchment and subcatchment
Select a catchment/subcatchment
Cost for project phases
Reasons for river restoration
Hydromorphological quality elements
Biological quality elements
Physico-chemical quality elements
Additional documents and videos