Trout return to waters cleansed of industrial filth

It was a colourful river, the Calder, 25 years ago. Bright red. Bright green. Bright blue. Sometimes all on the same day.

It was a colourful river, the Calder, 25 years ago. Bright red. Bright green. Bright blue. Sometimes all on the same day.

The long watercourse that snakes down from the Pennines through the most densely industrialised valleys of Yorkshire was one of the worst polluted in Britain.

At each of a series of mill towns, whose names sound like the Rugby League results - Halifax, Huddersfield, Dewsbury, Wakefield, Castleford - the once-pristine stream was walloped by a new set of noxious and lurid discharges, ranging from dyeing effluent to sewage, which choked the life out of it.

The Calder stank, it looked awful, and it contained no fish whatsoever.

Richard Armitage, of the Environment Agency, said: "Our classification of river quality runs from A to E, but in the mid-Seventies, the Calder would have been an N, if such a category existed. Out of all the rivers in the North-east region, it was the one that had been abused the most."

Times have changed. There are fish in the Calder now, and not just any fish: trout, whose presence indicates water purity. The state of the river illustrates dramatically how much progress has been made over the past few years in cleaning up the legacy of filth that the industrial revolution bequeathed to our rivers.

Direct waste discharges from textile mills, one of the worst sources of pollution, have been cut out, with the effluent rerouted through the sewers system, and sewage works all along the river have been hugely upgraded.

The biggest and most effective change has been the £50m improvement to Huddersfield sewage works, which Yorkshire Water have carried out at the prompting of the Environment Agency.

The Calder is now given a D classification, which means it has "fair" water quality, and it is improving all the time, with large numbers of fish returning.

"Anglers are reporting catches of 18lb a time, and at Dewsbury they are even catching small trout," Mr Armitage said. "The river has come alive again."