The installation of a new bridge over the River Senni is set to boost fish populations, reduce flood risk, and improve road access for local communities.

Officers from Powys County Council, in collaboration with Natural Resources Wales’ (NRW) Four Rivers for LIFE project, have replaced the deteriorating 1950s pipe bridge near Heol Senni with a clear-span steel bridge. The previous bridge relied on concrete pipes on the riverbed that frequently became blocked, restricting fish migration, harming river biodiversity, and increasing flood risk.

Installed earlier this year by A.V Plant Ltd, the new bridge design enables natural gravel movement along the riverbed, creating a healthier habitat for fish and invertebrates to feed and breed. This improvement will make approximately three kilometres of the River Senni more accessible for breeding salmon, trout, and other important species.

The River Senni is part of the River Usk Special Area of Conservation (SAC) and an essential spawning area for Atlantic salmon. Previous access issues limited salmon spawning in the river’s headwaters, and with salmon numbers declining across the catchment, unimpeded access to clean water and spawning grounds is vital for their survival.

Additionally, 'green engineering' has been applied to stabilise the riverbank upstream. Tree roots have been embedded into the bank to prevent erosion, and trunks of four to five metres in length have been anchored horizontally with chestnut stakes. Coir matting covers the trunks and is seeded with native vegetation, further reducing erosion and reinforcing the riverbank over time.

Cllr Jackie Charlton, Powys County Council Cabinet Member for a Greener Powys, said: “Working with NRW on this project has been great. We have been able to discuss different elements throughout the feasibility and design stage and develop and deliver a solution which meets the needs of everyone efficiently. 

“As well as helping the environment and biodiversity of the river and surrounding land, the local community will also benefit from the new bridge which will reduce the frequency that the road floods and is subsequently closed. The new clear-span structure will result in lower maintenance costs due to no longer having to periodically clear the blocked pipes of the original bridge.”