Major restoration work improves vital habitat on Pembrokeshire river

A stretch of the Cleddau River Special Area of Conservation (SAC), has been restored by Natural Resources Wales’s (NRW) Four Rivers for LIFE project.

500 tonnes of boulders were reintroduced into 650 metres of the Afon Wern - a key tributary of the protected Cleddau River SAC with the aim of improving the river habitat, supporting wildlife and restoring more natural river processes.

This stretch of the Afon Wern has suffered from dredging in the past, and surveys of the river by staff confirmed this, as the boulders that had been removed were found along the riverbank.

Over the summer, contractors carefully placed the boulders back into the river channel. These boulders will break up the river flow, increasing habitat complexity and creating diverse microhabitats for fish and other wildlife.

Boulders play an important role in healthy river systems, creating different flow patterns and providing pools, shelter and habitat for fish and aquatic invertebrates. Boulders also act to hold back and trap gravel needed for fish spawning.

Additional work also included digging a new channel to enable the river to flow out during heavy rainfall events. These measures will help to re-connect the river with its natural floodplain.

Three drainage ditches were blocked in adjoining fields to retain water on the floodplain longer, which, alongside digging shallow wetland ponds and scrapes, will boost wetland biodiversity and improve resilience to both floods and drought.

An obsolete concrete weir in this stretch of the river also acted as a barrier, preventing natural movement of boulders and gravels, and disrupting and delaying fish migration.

A notch was cut into the weir immediately restoring free fish passage and allowing the river's substrate to move naturally again. Even very small weirs can act as barriers to weaker swimming species such as eel and lamprey, as well as delaying salmon and sea trout migrations.

Peter Jones from the Four Rivers for LIFE project said:

“By working with natural processes, we are restoring ecosystem resilience of the Afon Wern and improving habitat quality for fish and other wildlife.”

“This restoration work will benefit numerous species including salmon, trout, bullhead, eel, lamprey and otter. We would like to thank local landowners and graziers for their support in delivering the scheme.”

Restoring natural flood dynamics will improve water retention at the top of this river catchment, reducing the impacts of flooding further downstream and increasing drought resilience.

The Four Rivers for LIFE Project is funded by the EU LIFE Programme with support from Welsh Government.