Rivers and the surrounding land drained by them (catchments) are very important wildlife habitats. The water itself provides the environment for fish, plants and animals, while the banks and nearby land support creatures such as otters, kingfishers and dragonflies and a variety of water-loving plants.

Between 1985 and 1990 there was a decrease in the total length of rivers and canals in England and Wales having top quality water. Meanwhile the total length of 'poor' quality waterways increased.

Since 1990 the situation in England and Wales has improved. The Environment Agency reports an increase in length in the best quality grades of waterway and a reduction in the poorest. Indeed there has been significant improvement in 10.7% of the total length of rivers and canals in England and Wales.

Where does pollution come from?

There are several sources of water pollution which work together to reduce overall river water quality. Industry and agriculture discharge liquid waste products. Rain as it falls through the air, or drains from urban areas and farmland, absorbs contaminants.

Serious incidents resulting from spillages or discharges of toxic chemicals are the pollution events that make the news. For example, just one litre of insecticide killed over 1,000 fish in the River Glaven in Norfolk. The impact of a slow build-up of pollution over a long time and in a wide area can be even more serious. During the 1950s, otters in many parts of the country were nearly wiped out by the accumulation of pesticides in our rivers

Acid rain

Rain falling through polluted air absorbs some of the pollutants as it falls. The main pollutant gases are sulphur dioxide and nitrogen oxides, which form when fuels are burned. They react with rainwater to form sulphuric and nitric acids.

On reaching the ground the acid liquid has many effects. It can release harmful substances such as aluminium and heavy metals from the soil. These are normally present in an inert, harmless state, but in acid conditions can turn into compounds poisonous to plant and animal life. When washed into lakes and streams the aluminium can kill small water creatures and fish. Particularly at risk is the dipper, a river bird which actually walks under the water to catch its insect food. If acid rain kills the insects then the dippers in their turn will disappear.

Industrial pollution

Many industrial wastes discharged into water are mixtures of chemicals which are difficult to treat. Some industrial wastes are so toxic that they are strictly controlled, making them an expensive problem to deal with. Some companies try to cut the costs of safely dealing with waste by illegally dumping chemicals at times and in places where they think they will not be caught.

Agricultural pollution

When organic farm wastes like silage or liquid manure (slurry) escape into rivers, the amount of oxygen in the water is reduced. Ten thousand fish died when pig slurry escaped into a tributary of the River Severn in 1 985.

Nitrate pollution problems occur when too much chemical fertiliser is applied to the land. The excess runs off and can find its way into drinking water sources, or can trickle into rivers and lakes. Some experts believe that high levels of nitrate in drinking water may pose a threat to health. A European directive states that drinking water should not contain more than 50 milligrammes of nitrates per litre of water.

In rivers, streams, ponds and lakes, too much nitrate can create a 'pea soup' effect. The water becomes clogged with fast-growing plant life like algae and weeds. This is a major problem especially in some areas of England such as East Anglia. In problem areas, some farmers voluntarily control their use of nitrogen .

Other sources of water pollution

Protecting rivers and streams

Both the European Union and the British government are concerned about water pollution. Water quality is protected by many different laws. England's first water pollution act of 1388 made it illegal to dump animal remains, dung or garbage into rivers. Anyone breaking that particular law in those days could be hanged.

The most important modern legislation is the Water Resources Act of 1991. It instructs the Environment Agency to police the use of water in England and Wales. The Environment Agency manages fisheries, flood defence, navigation, recreation and nature conservation. In Scotland, the River Purification Boards control river pollution.

The Environment Agecy protects water resources by issuing licences for drawing off large volumes of water (abstraction) from watercourses, and for the discharge of pollutants.

You can help

The Wildlife Trusts launched the Water for Wildlife campaign in 1992 to ensure that the water environment is respected and protected by everyone. At local level the wildlife trusts work hard to improve river catchments for wildlife. In many areas, wildlife is recovering and otters have returned. Joining your local wildlife trust is the first step to protecting your neighbourhood waterways.

The NRA asks that everyone should help protect the water environment by reporting incidents such as pollution, poaching and flooding to a national emergency freephone number - 0800 807060

Further reading

National Society for Clean Air and Environmental Protection (1995) Pollution Handbook. NSCA, Brighton. A comprehensive, detailed review of legislation and procedures relating to environmental protection.

Riverwatch publications. These include a report of Riverwatch, the nationwide 3-year study of the UK's rivers undertaken by children, and a series of activity packs for studying different aspects of rivers. Each pack is £5 (or £3.50 for Watch/WES members) or £16 for a boxed set of three packs and the results report (£13.50 for Watch/WES members) from The Wildlife Trusts.

Water for Wildlife - your action plan. Free leaflet (send SAE) from The Wildlife Trusts which describes how an individual can help.

NRA (1992) Water pollution incidents in England and Wales. NRA, Almondsbury. A concise summary of water pollution statistics.

If you don't know where to contact your local wildlife trust, then ask The Wildlife Trusts, The Green, Witham Park, Waterside South, Lincoln LN5 7JR Tel: 01522 544400

Did you know...

During 1994, over 35,000 pollution incidents were reported to the National Rivers Authority, of which 25,415 were substantiated.

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