Mereway Fish Pass

Mereway Fish Pass has been installed to allow fish (including eels) to swim upstream, avoiding the barrier created by Mereway Weir. The tilting weir, refurbished in 2020, helps to protect over 500 properties in the Twickenham area, allowing more water down the main channel at times (e.g. after heavy rainfall) when water levels are high. The fish pass has – for the first time in several hundred years – restored fish passage between the Lower Crane (and the tidal Thames) and the upstream river catchment. It came into operation in June 2024. 

The fish pass is designed to provide the connection between the River Crane above and below the weir via the Lower Duke of Northumberland’s River which flows off the main river at Mereway.  The presence of more fish above the weir will attract other wildlife, enhancing local biodiversity.

The video below shows the fish pass a week after it first became operational:          

Construction of the fish pass was a large-scale Environment Agency (EA) project, involving a number of partners including London Borough of Richmond upon Thames, Friends of the River Crane Environment (FORCE), Friends of Kneller Gardens and the Crane Valley Community Interest Company (as the hosts of CVP) . The EA also consulted with the general public. The area around the fish pass has been landscaped to include grass, meadow plants and wildflowers.  This will help to conserve and enhance habitats locally. This links to the wider work that London Borough of Richmond upon Thames is doing through its Biodiversity Action Plan, working with Habitats and Heritage.  

Often in summer when upstream river levels are generally low, the flow of water over Mereway Weir can be very limited with much of the available water going down the Lower Duke of Northumberland River instead.  An additional benefit of the new fish pass is that it will deliver some ‘sweetening’ flow from the Lower Duke of Northumberland’s River into the Crane, helping to protect the downstream habitat for aquatic plants and animals.

Having a fish pass in this location will be locally benefical but it will also help to facilitate some other fish passage projects elsewhere in the Crane river system. Information on other barriers to fish migration in the Crane Valley can be found in a recent report by the Zoological Society of London (ZSL) – click here to view.            

The image (right) shows Environment Agency contractors installing the technical fish pass (larinier).  Fish will swim through the series of baffles. [Eels will utilise the smooth (green) side.] 

[image courtesy of the Environment Agency]

The image (below) shows Mereway Weir in October 2022, with the newly constructed fish pass (covered over with a green grating). The fish pass became operational in 2024.

[image: Crane Valley Partnership]