The North Wessex Downs Area of Outstanding Natural Beauty (AONB) has today joined local farmers to ‘leave no stone unturned’ in helping to help trace the source of a polluting chemical found in the River Kennet.

The incident has been described as an ‘unspeakable disaster’ by Henry Oliver, director of the AONB.

After attending a high level meeting today, Mr Oliver said they would be supporting the farmers, the Environment Agency, Thames Water and the Action for the River Kennet (ARK) group, as well as other local organisations, to quickly get to the root of the crisis.

He said: “We are deeply saddened by this horrific pollution, which has devastated a 15km stretch of the River Kennet between Marlborough and Hungerford in the North Wessex Downs.

“However, we are pleased that downland farmers are already on the case to identify how and where the pollution took place.

“We understand that, at this stage, the origin of the pollutant is unknown and could be either domestic or agricultural. The chemical chlorpyrifos, identified as causing the pollution, is the same as used in some ant killer applications that can be bought at garden centres – though it is also used in commercial agri-chemical applications.”

He added: “The River Kennet is a chalk stream, usually known for water purity and lack of sediment. The spring-fed, fast flowing streams and rivers which cut through the chalk also support a diversity of plant and animal life, especially the diverse crustacean and invertebrate community, which have been wiped out by this chemical spill.

“The clear water supports healthy fish populations including brown trout, perch and chub – and these species will be left with nothing to feed on. “Eighty-five per cent of the chalk streams on this planet are located in England and a significant number of these are within 50 miles of the Marlborough-Hungerford axis.

“Thus, this tragedy on the iconic and much loved River Kennet strikes at the very heart of such an internationally renowned environment.” The farmers who have pledged to track down the source of the pollution are all members of the Marlborough Downs Nature Improvement Area (MDNIA), which has done so much to improve wildlife habitats on the Marlborough Downs.

Dr Jemma Batten, project manager for the MDNIA, said: “Our farmers are making a major contribution to the health of our local wildlife. We are devastated at the news that the gorgeous River Kennet has suffered this major pollution incident.

“We as farmers understand the profound importance of handling chemicals responsibly. We do all we can to ensure the farming community is never the cause of such a serious event.”

Charlotte Hitchmough, director of Action for the River Kennet (ARK), added: “With a chemical like this, if disposed of inappropriately only a small amount can cause a great deal of damage to wildlife. With such a wide range of users, searching for the source will be a major challenge.”