Culvert removal improves river habitat for migratory fish

Natural Resources Wales’s (NRW) Four Rivers for LIFE project has completed work to remove a culvert on the Afon Lwynor, a tributary of the Llandovery Bran.

The culvert (top image below) was part of a forestry track crossing and caused a significant barrier to fish migration due to shallow fast flows through the 12metre long sloping pipe.

The two metre diameter pipe also constricted the river, disrupting gravel movement and natural river channel dynamics.

The scheme replaced the culvert with a clear span bridge (bottom image above) as this was the most cost-effective way of restoring access for all fish species and restoring natural river dynamics.

The work has unlocked approximately 4.5km of upstream habitat on the Llandovery Bran which is part of the River Tywi. This work will benefit species such as salmon, trout, bullhead, river lamprey and brook lamprey.

Four Rivers for LIFE Team Leader Susie Kinghan said: “Removal of the culvert will now allow the river to breath and restore natural gravel movement, this bridge will give the river more room to move.”

Peter Jones Four Rivers for LIFE River Restoration Officer said: “Artificial barriers like culverts, have been highlighted as one of the leading drivers of declines in freshwater biodiversity and river ecosystem health. Projects like this are therefore essential to improving ecological resilience of our rivers to future environmental changes.”

The existing pipe and surrounding in-fill was removed from the watercourse. The legato block bridge abutments were spaced as wide as possible to allow the river plenty of room to move.

The design included steel beams and a plate deck suitable for taking the weight of fully-loaded forestry logging trucks. Block stone bank protection and some bed control riprap were added to minimise the risk of the abutments becoming undermined.

Wales-based contractor McCarthy Contractors Ltd designed and built the scheme. The work was completed in October 2025 before the start of fish migration and spawning in the river.

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