PESTICIDE pollution has caused an environmental disaster in the Ouse north of Lewes.
Environment Agency officers say it has wiped out insect life and killed hundreds of fish along a 12-mile stretch of river.
A broad range organo-phosphate pesticide, Chlorpyrifof-Ethyl, used to control caterpillars and other insects, has been found in samples taken from the river.
The amount of the chemical released is calculated to be small, only about half a pint.
But this has been sufficient to kill river bed invertebrates,and to cause the death of more than 500 fish, and seriously weaken thousands of others.
It is believed the pesticide entered the river just north of Newick.
The deadly area stretches south from Sheffield Bridge. Only the tidal barrier of the Hamsey Weir has prevented it from reaching the town of Lewes.
Anglers have been asked not to fish the affected area, and people should certainly not swim in it.
It is believed that the pesticide weakened the fish to the extent that they succumbed to a bacterial infection which attacked their flesh.
Fish were found in appalling condition . . . some still alive with their spines protruding.
Environment Agency area fisheries manager, Stuart Taylor said on Tuesday: The fish were in a shocking state and we have been working hard this week to try to get to the bottom of the problem.
We believe that the presence of the pesticide in the water was the initial cause of these fish deaths, although we will also be continuing to research the source of the bacterial infection.
The pesticide will de-activate within 10 and 20 days and the river will recover, but it will take time.
Our investigations have found that all aquatic insects along a 20-kilometre stretch from the Sheffield Bridge area downstream, have been wiped out.
This will leave a significant gap in the food chain.
Although molluscs have also been hit, we have seen some that have survived and there are also fish that remain healthy in the Ouse.
Fortunately the other tributaries are fine, which will enable the re-population of the main river.
We will be continuing to monitor the progress of the river very carefully over the next few months.
We have traced the point at which the pesticide entered one of the feeder streams of the Ouse and legal action is being considered by the Agency s legal team. The incident is believed to be the result of accidental spillage.
The amount of pesticide involved in this incident is small but it has caused tremendous environmental damage.
Individuals must take all the proper precautions when using any agricultural chemical and make sure that containers are washed out and disposed of properly.
The low concentration of the pesticide in the water means that it does