Farm chemicals are poisoning some of the country's most valuable wildlife, including salmon, dragonflies and pearl mussels, and pose a serious threat toriver environments.
English Nature, the Government's independent wildlife adviser, and the Environment Agency said in a report published yesterday that the problem is widespread throughout England because of intensive farming practices and the use of inorganic fertilizers.
Chris Mainstone, senior freshwater ecologist at English Nature, said it "could be solved within a few years if the correct measures are taken".
The problem occurs when phosphorus and soil particles leach from farmlands into water courses. There, the nutrients in the run-off feed the growth of plants and algae, leading to a process called "eutrophication", in which the decomposing dead plants starve the water of oxygen, killing off animals that need fast-flowing water in the streams.
The research found that rivers such as the Avon in Hampshire and the Wye in Herefordshire, both Sites of Special Scientific Interest (SSSIs), and also designated under the European Habitats Directive, are receiving very large loads of phosphorous and silt from farming.
In the catchment of the river Lugg, a tributary of the Herefordshire Wye, the researchers estimated that the total sediment load being run off annually from farmland to the river could be sufficient to fill up enough trucks to form a queue stretching 165 miles, 10 times more than would be the case under natural conditions.
Lake wildlife is even more vulnerable, since much of the pollution is trapped in lake sediments.
Intensive farming has meant that both animal waste and inorganic fertilizer run-off can reach rivers because hedges, which could absorb some of the flow, have been cut down.
The report outlines a national package to help farmers to control the problem, notably by changing methods in areas where water courses are vulnerable.Reuse content