PROJECT

Darent River, Questor Estate Eel Pass

The South East Rivers Trust has previously carried out fish passage and river restoration at Central Park in Dartford, part of the River Darent.

In March 2022, we carried out additional work as part of a broader programme to further improve eel and fish passage on the same river network.

With funding from the Environment Agency, we were able to design and install a more efficient eel pass on the Questor industrial estate while minimising maintenance needs. Over the coming year we will be designing and hoping to install a fish pass on the weir.

Questor weir pass The completed Questor weir pass © South East Rivers Trust

Why a new eel pass?

Questor weir is located inside Questor industrial estate on the River Darent. It is obstructing the movement of fish, including eels.

Some eel tiles were already present on the weir. However, the structure and flows still presented a significant barrier to eels migrating upstream.

The pass was also prone to debris blockages, therefore limiting the chance of passage further. For these reasons, we were keen to improve the pass.

Eels require a suitable substrate to crawl, so that they can overcome obstacles in the rivers in order to migrate upstream.

Unfortunately, the slippery concrete found on many weirs often impedes eels from passing through these structures. Eel tiles are used in these situations, as they are designed to facilitate the upstream movement of different sizes of eels.

Although an eel pass had previously been installed on the weir, they were not covering the whole length of the concrete and were also very prone to becoming blocked with debris and vegetation.

Cutting a notch on the weir's crest

Horizontal tiles

To help eels overcome the weir and access a whole new section of the River Darent, we installed 22 linear metres of horizontal eel tiles along the whole length of the weir.

These will assist both elvers and eels to pass the barrier, enabling them to reach habitats located in the upstream section of the river.

The new eel pass will require minimum maintenance because accumulated debris and blockages will be washed away during higher flows.

Over the next couple of years, we plan to make the weir passable to more species of fish.

Installing the eel tiles at Questor weir © South East Rivers Trust

Thanks to our supporters

Environment Agency

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