AROUND 4,000 fish have been killed after one of the biggest river chemical spills in Essex for a decade-and-a-half, the Environment Agency says.

A pesticide spill in Toppesfield Brook near Great Yeldham has affected 10 kilometres of the River Colne.

It’s expected to hit Colchester by Saturday.

But the agency say there will be no major effects by this point because the pollution will have been diluted by the widening river.

Frank Saunders, from the Environment Agency, said: ‘We are continuing to do all we can to minimise the impact but unfortunately we have seen some devastating effects so far. This is one of the biggest chemical spills into a watercourse in Essex in the last 15 years.

“We ask that if people see fish gasping or dead anywhere along the river, please ring the Environment Agency immediately on 0800 80 70 60.”

The agency has moved around 6,000 fish to safety so far. However, they estimate that 4000 larger fish and many thousands of smaller fish, invertebrates and flora have been killed.

The pesticide is now very dilute and does not pose a significant risk to humans, but if anyone has been in contact with the water and is at all concerned, they should contact NHS Direct. Dog owners are being advised to keep their pets out of the water as a precautionary measure.