New weir to be built to help salmon migration

The Environment Agency is planning to build a new weir at the head of St James leat at Exeter, in Devon, to help salmon swim more easily up the river to their spawning grounds.

The weir has been designed to restrict flow into the leat and increase flow over the main river weir during periods of low flows.

Increasing the proportion of flow in the river will also enable the Wimberball ‘water bank' to be used more effectively and encourage fish passage over St James Weir.

This project is funded primarily by South West Water, as part of the work improvements being made to the Wimbleball reservoir in Somerset.
South West Water's Water Strategy Manager Neil Whiter said: ‘We are working with the Environment Agency to fund the construction of the new weir. This work will have a positive impact on salmon migration in the River Exe, which is also a vital water resource for Exeter and much of the surrounding area.'

The work is due to start the week beginning 21 May 2007 and is expected to last for approximately eleven weeks.

The work entails the construction of a stone-faced wall across the manmade water channel, which has been designed so that water will flow over the whole of the lip of the weir, except for when water levels are low.

‘As part of the construction we will need to drive steel sheet piles into the riverbed to form part of the foundations. The piles will be driven using a vibrating pile hammer to reduce the amount of noise generated during the activity,' said Andrew Latham for the Environment Agency.

‘It is thought that the piling work will take five days to complete and be carried out between 9am and 4pm. We apologise for any disruption or inconvenience but hope this will be kept to a minimum.'

The stone from the existing weir is to be re-used and all other materials will be from sustainable sources wherever possible. Planting trees and shrubs in the near vicinity will offset the carbon footprint generated from the work.