The Great Stour Project - River Pollution

Farmland (orchards)

Fruit farming locally forms part of the North Kent Fruit Belt. Orchards, small fruits and hops are all grown in this area, taking advantage of the lighter sandy soils of the Tertiary rocks, sandwiched between the heavier clay soils to the north and the Chalk loams to the south, (see geology.)

Pollution threat from orchards

The potential threat to water pollution comes from the intensive use of pesticides. 'Pesticide' is a general term which includes herbicides, fungicides and insecticides. They are widely used for weed control in agriculture, but also on roadsides and railway embankments. Spray drift from pesticide application can enter water courses if orchards are located too close to the river. The main threat however comes, not from spraying, but from poor storage and accidental spillage, as a result of which pesticides may get into, and contaminate, the groundwater.

Pesticides are persistent in the food chain, since the chemicals involved are non-degradable; they are said to 'bioaccumulate' in the food chain. Organochlorides are found to cause changes in the sexual and reproductive characteristics of wildlife. Top carnivores (in the river, fish) are especially affected. Since pesticides are found in very low concentrations in water, their detection and measurement is complex and expensive. The maximum admissible concentration (MAC) is extremely small - 100 ng/litre or 1 part in 10,000,000 for any one individual substance, but 500 ng/litre for total pesticide residues.

Orchards (the local situation)

According to the

, spray application has never been a problem locally. Triazines and Drins are representative groups of pesticide compounds, minute traces of which have been detected in the Great Stour.

The following traces of pesticides were recorded in the river at
Bretts Bailey Bridge (GR 187602) on June 4th 1999:

It can be seen that this is well within the EU Directive of 500 ng/l and thus poses no threat to water supplies. There were no recorded failures in this category of water pollution in the period 1995-1997. It is interesting to note that certain banned substances are still detectable. The Water Act (1989) lists these pesticides which are now banned in the UK including DDT, Dieldrin, Fenitrothion, Malathion, Endosulphan, etc. Their presence in the river is testimony to their persistence, clearly pre-dating the 1989 ban.

Orchards (pollution prevention)

Local farmers follow the MAFF "Code of Good Agricultural Practice" and are required to produce a "Farm Waste Management Plan" for the Environment Agency. See Farmland (Arable) for more details. Correct spraying techniques have to be observed, under safe weather conditions.

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