NRW to enhance fish and eel passage at Afon Gwyrfai weir

Natural Resources Wales (NRW) is set to begin essential works at Bontnewydd weir on the Afon Gwyrfai to improve fish and eel migration.

The weir has been identified as a barrier to fish movement, and planned modifications will help species such as salmon and eels move more freely upstream.

The work will involve replacing the current fish pass (rocky ramp) immediately downstream of the weir to improve fish passage. An eel pass will also be installed by modifying the weir’s surface to create a rough, brushed finish that eels can grip.  We will also repair part of the wing wall on the left-hand bank, which is currently being undermined.

To minimise disruption, the river will not be fully dammed at any time. Instead, only half of the channel will be worked on at once, allowing water to continue flowing. The construction of the new fish pass  will be carried out in six sections, making it a time-consuming process, as stones need to be placed by hand into the concrete base. The wing wall will be replaced like for like once all other in-channel works are complete.

Site access works are scheduled to begin in April, with in-channel works starting in May. The project is expected to be completed by September 2025, though weather conditions may affect timings. Work will take place between 8am and 6pm on weekdays, with noise reduction measures in place.

The works will be undertaken by William Hughes (Civil Engineering) Ltd. Residents and businesses directly affected have been informed, and NRW will continue engaging with landowners to minimise disruption.

Sian Williams, Head of North West Operations at NRW, said:

“These works will help fish and eel species migrate more easily along the Afon Gwyrfai, supporting the long-term health of the river’s ecosystem.

“We understand that construction can be disruptive, and we are working closely with landowners and local communities to minimise any inconvenience. We appreciate the patience and cooperation of residents as we carry out these essential improvements.”

For further information, visit the project webpage or contact the project team at enquiries@naturalresourceswales.gov.uk.