A few years ago the River Aire in Castleford, West Yorkshire, was grossly polluted.
Now a £379,000 fish pass has been built to allow salmon to run upstream.
It is 200 years since the former mining town last saw the king of the river. Recently salmon have been caught by anglers. The transformation in the river has come about because of a dramatic improvement in water quality thanks to a reduction in industrial discharges.
The Environment Agencys Darren Starkey says: We are looking forward to seeing how successful the fish pass is. We should start to see fish getting farther upriver.
The pass will allow fish to circumvent a weir by a series of baffles and a new footbridge will provide a vantage point to watch leaping salmon.
The Aire has more than 30 weirs but only six have fish passes. The Castleford pass is part of an area revival project.