500 tonnes of boulders returned to river to restore wildlife habitat

Nation.Cymru staff

Hundreds of tonnes of boulders removed by dredging have been put back into a river to create shelter for wildlife and improve fish spawning grounds.

Contractors returned 500 tonnes of rock to a 650-metre stretch of the Afon Wern in Pembrokeshire, a tributary of the protected Cleddau river system.

Natural Resources Wales (NRW) staff surveying the river found boulders left on the banks after earlier dredging. Over the summer, contractors placed them back in the channel to vary the speed and direction of the water, creating pools and shelter for fish and other wildlife. The rocks also trap gravel that fish use to spawn.

A notch was cut into a disused concrete weir, allowing fish to move freely through that stretch of the river again. NRW said even small weirs can block weaker swimmers such as eels and lampreys and delay the migration of salmon and sea trout.

The work also included digging a new channel so water could spill onto the river’s natural floodplain during heavy rain. Three drainage ditches in adjoining fields were blocked and shallow ponds were dug to hold water for longer. NRW said the changes would help reduce the impact of flooding downstream and make the area more resilient during droughts.

“This restoration work will benefit numerous species including salmon, trout, bullhead, eel, lamprey and otter,” said Peter Jones of NRW’s Four Rivers for LIFE project.

“We would like to thank local landowners and graziers for their support in delivering the scheme.”

The project is funded by the EU LIFE programme with support from the Welsh Government.