Water voles set to benefit from removal of River Stort weir
Removal of the River Stort weir at Grange Paddocks, a popular paddling spot for children and dogs, is set to take place this autumn or spring next year.
Following a feasibility study, Hertfordshire County Council and the Environment Agency (EA) have completed detailed designs for the work – which will include creating steps down into the water – and habitat restoration.
Water voles are set to be one beneficiary of the improvements. Surveys carried out in August 2021 and May this year showed no sign of activity by the semi-aquatic rodents in the area impacted by construction, although small populations have previously been recorded around Grange Paddocks.
On-site checks will be made before and during work for the voles, which are a vital part of river ecosystems. The ultimate aim is that removing the weir will encourage the voles to migrate and colonise upstream.
As part of the weir removal project, contractors will use imported gravel and timber flow deflectors to restore the section of the waterway near the leisure centre and playing fields to a natural chalk river.
The scheme also includes riverbank protection measures; an updated EA telemetry point for river level measurement and flood warnings; an upstream wetland area off of Bourne Brook to provide additional habitat diversity; and creation of safe, informal steps to the river near the current weir.
The next move is to secure an “impoundment licence” from the EA. This will include public consultation where, in a similar way to a planning application, stakeholders and members of the public can make submissions.
An EA flood risk activity permit will also be applied for. Modelling shows removing the weir will reduce risk to many areas, both upstream and downstream, including residential and commercial properties. The study indicated no increased flood risk to any buildings.
The agency and county council have liaised with police to discuss any security implications for riverside homes linked to the weir removal. The force was confident that the combination of the deep water of the river combined with vegetation cover would continue to offer good defensive protection. Officers were also happy to advise householders.
In March, Bishop’s Stortford Town Council and its Waterside Stortford partner, the Canal & River Trust (CRT), teamed up with the Environment Agency to create a habitat for the creatures, one of the UK's fastest-declining mammals, by installing a 60m stretch of pre-planted coir rolls along a steep bank of the Stort navigation, close to the Goods Yard footbridge.
In 2015, the Essex Wildlife Trust and Herts & Middlesex Wildlife Trust re-established a water vole population on the Stort downstream at Thorley Wash Nature Reserve.