The state of River Chess was labelled “deeply depressing” after sewage was released for over 500 hours.

The Chesham treatment works started discharging at 6.45am on February 29, according to a live map run by Thames Water. 

It means that it has now been releasing overflow water with potentially raw sewage into the waterway for over 500 hours and counting. 

After visiting the site yesterday, River Chess Association chair Paul Jennings said the conditions were “as bad as I've ever seen”.

“Yesterday was deeply depressing because it felt as if we'd taken so many backward steps seeing so much pollution,” he added.

“The day before that, we were getting people phoning us up saying it's the worst they've smelt it in their time living close to the river. It's just so, so depressing”

The River Chess is a chalk stream which runs through the Chess Valley from Chesham to Rickmansworth, where it then joins the River Colne.

Watford Observer: Paul said that excess sewage water had spilled over into Blackwell Hall Lane and into a neighbouring field.Paul said that excess sewage water had spilled over into Blackwell Hall Lane and into a neighbouring field. (Image: Paul Jennings)

River Chess Association chair raised concerns that "solid" sewage material was present in the stream yesterday, something he hadn't seen before.

Paul added that additional waste water from the sewage treatment works had spilled over on Blackwell Hall Lane and into a nearby field at least four times in the last few weeks.

He is not hopeful that the issues will be resolved soon: “They may stop it intermittently but it will be a daily event probably for another two to three months.”

In a statement to the association, dated March 11, Thames Water admitted that the Chesham treatment plant had “a history of prolonged storm discharges” and that “high volumes of unwanted surface water” can enter the sewage system in areas like the Chess Valley.

Watford Observer: Excess water has spilled into a nearby field as Thames Water admitted that the Chesham treatment plant had “a history of prolonged storm discharges”.Excess water has spilled into a nearby field as Thames Water admitted that the Chesham treatment plant had “a history of prolonged storm discharges”. (Image: Paul Jennings)

It said it had invested over £4 million in increasing the facility’s capacity by 40 per cent, meaning it can treat at least 353 litres per second of wastewater before it needs to use the storm tank.

Thames Water added it had lined 144m of sewers and sealed 256 manholes to keep surface water out.

“We are clear that such discharges of storm sewage are unacceptable, even when they are permitted, and we are working to reduce them in the Thames region, in line with government targets.”

It added: “We absolutely recognise that more needs to be done and have more work planned that will both reduce further the amount of unwanted flow entering the sewer system and increase the resilience of the sewage treatment works.”