Fish pass works set to continue at Walsham Weir

Works to construct a new fish pass at Walsham Weir on the River Wey in Surrey – being carried out on behalf of the Environment Agency – is set to resume this month.

A key part the Environment Agency delivery team and delivery plan, this project supports the Wey Navigations and will protect around 408 residential houses and improve fish and eel passage on 27km of the River Wey by 2021 and with the Wey Fisheries and Wetland Delivery (FWD) project to extend this up to 100km.

The fish pass upstream and alongside Walsham Weir will be a mixture of a 170m long naturalised channel with fish-friendly hard structures that reduce the water flow rate so that fish and eels can make their way upstream.

Construction started in 2020, but was interrupted by Covid-19 and involves installing a piled inlet with riprap (rock armour) with a culvert under the towpath. This will feed into a meandering, vegetated channel flowing into a piled hybrid brush pass outlet with sloped banks to reduce the visual impact.

Remaining tasks to be completed as part of the project include excavating the meandering channel, installing plastic sheet piles on new embankments and a timber footpath bridge. Wetland, shrub planting and fencing will follow.

Mackley initially completed the downstream works and installed the culvert upstream to allow the towpath to be re-opened for the winter period. The site was then safely closed down, with works now set to continue.

Part of a wider scheme
The works including Walsham Weir, being carried out with an integrated team including Jackson Hyder/Arcadis and Fishtek, are part of the Wey Weirs Refurbishment and Fish Pass Project.

The £12M project is being carried out by Mackley working as part of Team Van Oord and on behalf of the Environment Agency, the National Trust and other local stakeholders.

It is designed to reduce the risk of flooding and improve fish and eel migration along a key 27km stretch of the River Wey in Surrey. The project will also open up around 100km of passage to the River Thames for the first time in centuries.

The project consists of replacement, refurbishment and repair works to seven weir sites – while replicating and preserving the historic designs of the weirs – alongside installing five fish/eel passes at priority sites, to bypass the weirs.

The weirs, owned by the Environment Agency, control water levels for the purposes of navigation and flood prevention and were and are in urgent need of repair or reconstruction to prevent operational or structural failure.

Meanwhile, the new fish and eel passes will form a chain that will allow fish and eels to migrate from the River Thames to new feeding and breeding areas – which, in turn, will improve populations of coarse fish species, eel, salmon and sea trout in the River Wey.

The seven sites covered by the project are:

  • Hamm Oils Mill Weir and bypass channel fish passes, Weybridge
  • Walsham Weir and naturalised fish pass, Ripley
  • Newark Weir and eel pass and Abbey fish passes, Woking
  • Broadmead Weir and eel pass, Woking
  • Bowers Mill Weir, Guildford
  • Stoke Mill Weir, Guildford
  • Millmead Weir and naturalised fish pass, Guildford

The first two weirs, at Hamm Oils Mill and Walsham, were successfully completed and handed over in 2018. Bowers Weir and Newark Weir and eel pass followed in 2019.

In 2020, the team and Mackley successfully replaced the Broadmead Weir and installed an eel pass – as well as retrofitting a fish/eel pass to the Abbey Weir at Newark.

The Walsham fish pass will be completed, alongside Hamm Oils and Millmore fish passes, in 2021. Millmead Weir is planned to follow in 2022.

12 April 2021

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