FISH stocks in rivers leading to the Severn Estuary could face extinction if a barrage is built, according to campaigners.
Members of the Stop the Barrage Now group believe fish using the estuary to go between freshwater spawning sites in the Usk and Wye could be wiped out due to a barrage.
The issue has also been highlighted by The Severn Rivers Trust and the Salmon and Trout Association.
A campaign spokesman said: “These rivers contain EU-protected species including salmon.
“A barrage would act as a physical barrier to movement and would also result in adverse environmental and water quality changes.
“The estuary is also hugely important for its intertidal habitats, which are dynamic environments that are used by both freshwater and marine fish species.
“A report by the Sustainable Development Commission predicts a barrage would result in the loss of 14,000 hectares of intertidal habitat.