Marlborough residents are being urged to avoid the town river reserve after raw sewage has been left to fester for over a month.

The Stonebridge Wild River Reserve was first flooded with debris and raw sewage when unprecedented floods on January 5 caused a sewer lid to open and the contents to pour into the river.

The incident was reported to Thames Water and the Environment Agency, but Action for the River Kennet group (ARK) is now urging people to stay away as the mess still has not been cleaned up.

“Please don't use the beach area,” said a spokesperson for ARK. "Despite numerous phone calls with Thames Water, no flooding debris clean up has been carried out after the sewer life ‘popped’ and 10 days of untreated waste cascaded onto the beach area and into the fragile chalk stream.

“The area has a strong stench and lots of what came out of the sewer remains on the land.

“We’ve been told a clean-up will happen in the next 72 hours, but we are not holding our breath.”

The Wiltshire Gazette and Herald: The sewer lid which was 'popped open' during flooding on January 5.The sewer lid which was 'popped open' during flooding on January 5. (Image: ARK)

Stonebridge Wild River Reserve, which has been overtaken by sewage, is an access point where ARK regularly take school children into the river to learn about the environment and nature around them.

The area was a well-known beauty spot for spawning wild brown trout and breeding kingfisher but due to the ongoing health hazard, ARK has stopped all trips to the river reserve with the children.

"Sewage, fuel, chemicals, and rubbish have all been washed into our rivers, which are already struggling against a daily onslaught of contaminants," said Charlotte Hitchmough, director of ARK.

"This incident is not isolated. Across Ogbourne, Aldbourne and Lambourn sewers are spilling untreated sewage into the street and down to the river, long after the flood has passed.”

The Wiltshire Gazette and Herald: The Wild River Reserve has turned from an educational beauty spot to a mass of sewage.The Wild River Reserve has turned from an educational beauty spot to a mass of sewage. (Image: ARK)

Speaking to the Gazette and Herald on January 18, a spokesperson for Thames Water said: “We’re aware of a reported pollution from a manhole at Stonebridge Wild Nature Reserve in Marlborough.  

"At first we had difficulty locating the manhole and apologise for the length of time it has taken to investigate.

"We've since attended the site, where we confirmed there was no blockage in the sewer system and the recent river flooding likely caused our local sewer system to overload resulting in heavily diluted wastewater to escape from nearby manholes.

"We will assess the site and see if a clean-up is required.”