Taming the Flood: Rivers, Wetlands and the Centuries-Old Battle Against Flooding. Jeremy Purseglove

sonnet, it is over in the space of a summer day, until next spring.

      When I consider every thing that grows

      Holds in perfection but a little moment.⁴

      The life of a river has nothing to show more resonant of changeless change than the life cycle of the mayfly, a genus known even in the dry language of science as Ephemera.

      Yet the return of the mayflies is no longer as inevitable as the return of May. They are steadily declining in many rivers, and have vanished from others. Pollution and the removal of riverside hedges have played their part; but above all, dredging and drainage have ironed out the varied bed conditions of gravel and silt to which the larvae of these and many other insects were so minutely adapted.

      The otter, sliding up a river like a sleek cat and whistling to its mate under the moon, is truly king of the waters, and the presence of otters on a river system sets the final seal of well-being on its wildlife. The otter has captured popular imagination ever since the classics of Henry Williamson and Gavin Maxwell. It achieved tabloid status in April 1985, when it was on the front page of the Daily Mirror’s conservation shock issue; and, as a symbol of wildlife under threat, it is a sure money-maker for such causes as the World Wildlife Fund. The fact that people will give money to save the otter, a nocturnal animal whose presence is detected even by full-time otter survey teams only by its tracks and droppings, is the best answer I know to that mean-spirited and illogical argument: ‘What’s the use of saving it, if I can’t see it?’ It was enough simply to know that otters were out there somewhere. Alas, no longer. In 1977 leading conservationists produced a report showing that the otter had declined with disastrous suddenness.⁵ Whereas otters were present, even common, throughout the country in the 1950s, they are now abundant only in the extreme north-west of Scotland, leaving core populations in Wales and the West Country, and a dwindling interbred group of individuals in East Anglia. Hunting, disturbance, and pesticide residues had all played their part; but the major culprits were river boards and their successors which scoured the banks of undergrowth in which otters lay up during the day, and felled the mighty riverside trees, such as ash and sycamore, in whose buttress roots otters made their holts. Since 1977 otter hunting has been illegal, and the ban on the pesticide Dieldrin is starting to have a beneficial effect. But the many miles of treeless river inhibits recolonization by otters, and even in the 1980s there have been cases of water authority workers felling known otter holts.^fn4

      THE CULTURAL HERITAGE OF RIVERS

      It is not only wildlife that is at stake. Rivers represent a cultural heritage as well. Through aeons of geological time, rivers, in the wake of glaciers, have helped shape the very structure of our landscape. When civilization arrived, rivers shaped human history, and humans, in turn, began to shape the rivers.

      From the time that the tribal Belgae and then the Romans invaded England, rivers dictated the positions of many towns and villages. It is believed that the great bluestones of which Stonehenge is constructed were floated up the Wiltshire Avon. Christianity came to England up a river, when St Augustine and his forty monks travelled to Canterbury up the Kentish Stour, ‘singing all the way’. Rivers were also highways of terror. The sleek hull of a Viking boat was specially designed to be shallow enough and narrow enough for use on navigable rivers, along which Norsemen brought fire and the sword. Along the waterways was carried most of the stone required to build our medieval cathedrals. When Whittlesey Mere was drained in the 1850s, a heap of dressed stone was found at the bottom of the lake, evidence of a medieval boating accident. It is thought that the cargo was destined for Crowland Abbey.^fn5

      In the eighteenth and nineteenth centuries the harnessing of water power for mills, and river navigation, interlinked with a new system of canals, laid the foundation for the Industrial Revolution. Through all this change, rivers have continued to flow; but, for those who have eyes to see, the imprint of each generation remains, varying and concentrating the character of each stream that flows past our homes and our lives.

      A good example of this is the water mill. The Romans introduced water mills to England, and the Domesday Book records as many as 5,624. All but a hundred of these mill sites can still be accounted for. Up and down rivers and brooks, the remains of some of these and many later water mills can be seen. In some cases, magnificent buildings, complete with all their machinery, still stand. Elsewhere there are just clues to former occupancy: foundations, a silted millrace, or the remnants of a weir, as described by Edward Thomas:

      Only the idle foam

      Of water falling

      Changelessly calling,

      Where once men had a work-place and a home.⁶

      All this human interference with rivers, the building of millraces and millponds and, in some cases, quite major diversions of watercourses, did not destroy the essential character of rivers. On the contrary, it added to it, and not just in terms of the quality and character of the landscape, but also from the point of view of the wildlife. A tumbling weir creates the localized conditions of an upland brook wherever it crosses a silty lowland stream. Here grow the willow moss and liverworts found again in abundance only towards the sources of a brook. In the highly oxygenated water below a weir swim the little fish not known for nothing as the ‘miller’s thumb’: the flattened head of the fish was often compared with the thumb of the miller, worn it was said from testing the flour. Perhaps the loveliest of upland specialists associated with weirs and mill sites is the grey wagtail – grey in name, but not in appearance, with the flash of his canary-coloured chest. The grey wagtail nests in ledges and crevices of rock upstream, and finds a similar home in the crumbling walls and vertical structures of water mills. Edward Thomas may not have known that he was also making an ecological point when he pinned down so precisely the atmosphere and feel of these places:

      Attractive colonizers of the mill weirs. Grey wagtail and the delicate leaves of skullcap.

      The sun blazed while the thunder yet

      Added a boom:

      A wagtail flickered bright over

      The mill-pond’s gloom.⁷

      Some of the wildlife of the water mill may owe its existence to a rather more conscious decision on the part of some long-dead miller. Growing along old millraces or near millponds are some of the stoutest and hoariest of pollard willows, which are the glory of any river bank. This is no accident. The willow was put to many uses by millers. An integral part of mill machinery was a simple spring known as the ‘miller’s willow’. In the most recent mills it was made of steel; but more commonly it was a piece of springy willow wood collected from a convenient pollard. Willow was also used for eel traps, and the fact of a river being carefully directed to drive a water wheel has always made water mills very convenient places to catch eels. The Luttrell Psalter of 1338 illustrates a water mill complete with eel traps which look very much as if they have been made out of pliant willow stems. Many medieval millers paid their rent to the lord of the manor in eels; and when the water mill in the centre of Stafford was pulled down after the Second World War, the laconic miller expressed as his only regret: ‘I shall miss the eels.’

      More recently, eel traps have been built into the systems of weirs and sluices of water mills. Yet these structures, too, add variety and local character to rivers. The joints in a timber lock-gate or the eroding mortar of a sluice often provide congenial conditions for gipsywort or skullcap, with its clear blue flowers. Both these delicately proportioned plants have more difficulty competing with other vigorous vegetation on the open river bank than they do in the neat crevices provided for them by mill structures. The structures themselves were often built of local materials. Before the advent of railways, it was cheaper to do this than to import materials from far afield. Later, bricks were commonly imported, but even these, including the splendid ‘blues’ of the industrial Midlands, added their individual stamp to river landscapes. Nevertheless, it is surprising how often local builders simply took advantage of what was at hand. In 1985