Fish will Jump as Weirs Come Down

A national programme to restore our rivers, help wildlife and reduce flooding is underway at a number of pilot locations including one in East Sussex, where it’s hoped fish species and wildlife populations will increase following the removal of weirs on the Ouse River.

The projects are being undertaken by local river trusts in conjunction with the Environment Agency. They stem from the EU Water Framwork Directive (WDF 2000), whereby Britain has just 15 years to bring its coasts and waterways up to ‘good ecological status’. Given the strength of local guardianship in many areas, it’s been decided that a bottom-up approach is the way forward.

In East Sussex, the Ouse and Adur River Trust (OART) are planning to restore a large section of the Middle Ouse and Uck Rivers from Barcombe Mills near Lewes to Ardingly Weir near Haywards Heath. The first phase is to remove weirs at four sites at Buxted, Sharpsbridge, Spring Farm (near Sheffield Park) and East Mascalls at a total cost of £500,000.

Studies show that the improvements are likely to be dramatic in terms of fish numbers. One decaying weir at Fletching Mill fell down of its own accord after its waters had been tested in 2009. Then, only five species of fish were caught in the sample. Three years later, with the weir gone, there are 12 species thriving with significantly higher numbers.

These pictures follow the removal of the weir at Buxted Park,  a complicated project. A huge two part weir has been in place for a number of years, comprising a top section with an iron frame and wooden boards, and further down the river a second, lower, concrete weir.

Behind both, a red footbridge is embedded in the bank, meaning that any change to the level of the river and the water level in the surrounding soil could easily result in damage to the bridge. Bank collapse is a common occurrence following the removal of a weir, so every removal involves a plan to either manage or prevent the bank from collapsing into the river.

Volunteers had already started to remove the plank damn by taking out the planks from the upper section.

But realising the 2.5m fall in the water level that would result, the team realised that work would be needed further upstream when the deep water banks collapsed down to the new level. With funding, advice and expertise from the Environment Agency, they have now removed the steel supports, erected willow weave fencing upstream of the bridge to support new lower level banks and put gravel on the river bed to encourage spawning.

There are many aims behind the project. One is to help the famous Sussex sea trout spawn upstream. But in terms of wildlife, it’s not just the sea trout that will benefit. Most freshwater fish move between different habitats seasonally to spawn, overwinter and shelter from inhospitable conditions like floods and droughts. Eels will also benefit from a shallow river, and eel mats have been laid to assist their movement into the higher reaches of the river.

 

Peter King from the Ouse and Adur River Trust wants benefits for all those who use and depend on the river, be they aquatic creatures, mammals, birds or the many human varieties of stakeholder. Whilst rivers are the responsibility of the Environment Agency, the land through which they run is often privately owned. Meanwhile anglers have fishing rights and many other people use the river for a variety of recreation purposes.

“My job is to make sure that everyone feels the river has been improved as a result of what we are doing, so I spend a lot of time talking to lots of different people.” says Peter.  ”We want this project to be a success in the long term so everyone must be happy with the outcome.”

 

Other Sources: Environment Agency Planning Document

Contact: morph@environment-agency.go.uk

OART