Nature Studies: We’ve cleaned up most of our rivers – but what about the rest?

Chalk rivers in particular are being hard hit by a subtle form of pollution

The River Test in Hampshire is in ‘awful condition’ (ALAMY)

In post-modern literary criticism, a “narrative” is a version of events, which may not be true, but which everybody believes. Here’s a good example.

It is 12 years next month since the Environment Agency first proclaimed that rivers in England and Wales were now cleaner than at any time since the start of the industrial revolution 200 years ago.

It was a significant moment; although the announcement was greeted with some scepticism, there was also widespread recognition that things had indeed changed, and the phenomenon of the watercourse whose waters flow lurid orange with industrial wastes was becoming largely a memory.

Michael Meacher, Environment Minister at the time, remarked: “People don’t come back from the dead, but rivers do”; as if to prove him right, on the very day he said it, the first salmon for 130 years were caught in the River Mersey. And it is true that we have cleaned up the worst of the industrial pollution of our rivers; to be technical, we have dealt with what is known as point-source pollution, that is, stuff pouring out of the end of a pipe. Most of that’s gone, thank God.

But this particular narrative – that our rivers are generally now OK – is being fiercely challenged by people concerned with the welfare of what are often regarded as the loveliest rivers of all, the chalk streams. These are the rivers that rise on the great band of calcium carbonate that stretches diagonally across England from Dorset, through Salisbury Plain, the Berkshire Downs and the Chilterns, to Norfolk, Lincolnshire and Yorkshire.

Because their water is filtered by the chalk, it is “gin-clear”, and almost unimaginably pure, and because it is so alkaline, it supports a profusion of plant, insect, and fish life. Many people consider these the most beautiful rivers on the planet – I’m certainly one – and the 161 of them which occur in England, from the queen of them all, Hampshire’s River Test, down, represent 85 per cent of the world’s chalk stream resource, most of the rest being in Normandy.

While Northern industrial rivers like the Mersey were running orange, people would point to the chalk streams as the ideal of river perfection; but now the positions are reversed.

The chalk rivers in their turn are being hard hit by a subtler form of pollution, far harder to deal with than the point-source variety. This is diffuse pollution, meaning it comes from an infinite number of sources – principally, the run-off of silt and agricultural chemicals, both fertilisers and pesticides, from farmers’ fields. They are also being clobbered by over-abstraction of their water by water companies, desperate to get their hands on such pure stuff.

Leading the campaign for the chalk streams’ plight to be recognised is the Salmon and Trout Association, which in recent years has morphed from a purely anglers’ organisation into more of a pressure group for the aquatic environment. It is playing hardball; it has made an official complaint to the European Commission that the Government is failing in its duty under the EU Habitats Directive to look after the Hampshire Avon, a chalk river whose salmon numbers are a mere fraction of what they should be.

“A significant number of the English chalk streams are now in a degraded state,” said Paul Knight, the S&TA chief executive. “We need policies on land management and abstraction to put them right.”

To prove his point, last week he invited me to a part of the middle Test, which at first glance – ie, on the surface – looks exquisite: but an expert eye sees a different picture under water.

Parts of the gravel beds trout need to spawn in are now covered in silt, others by “blanket weed” algae fertilised by agricultural phosphates, and the water level is far below what it should be; a sample of the invertebrate life of the river bed shows that the abundance of freshwater shrimps and mayfly larvae that would normally be expected is simply not there. “I think the river’s condition is awful,” Paul Knight said.

It may well be true that most of our rivers do have less industrial pollution in them than they did. But that’s only one narrative. There’s another: that some of the loveliest of all our rivers, even if it’s harder to recognise, are now in serious trouble in a different way.