Sewage has finally been pumped out of a rare chalk stream in the centre of St Albans, months after excrement and other pollutants were reported to authorities.

Thames Water removed the waste from the River Ver on Monday, and said an investigation had established that a nearby commercial property was responsible for the pollution.

Sewage entered the fragile stream where it flows near a footbridge off Holywell Hill, close to Westminster Lodge and the former Duke of Marlborough pub.

An annoyed neighbouring resident who first saw excrement near reeds at the location about 12 months ago said: “It is disgraceful.”

The man, who did not want to be named, added: “The river has been in an appalling state – and I have reported it at least half a dozen times to the Environment Agency. But no action has been taken to stop the culprit.

“It’s absolutely disgusting that sewage is in the stream. There is a sort of milky effect, and it looks like there is urine and faeces in the water. It smells too.”

When in full flow the River Ver, one of just 163 chalk streams in the world, goes through Markyate, Flamstead, Redbourn, St Albans and Park Street - where cattle graze alongside it - through to Bricket Wood, where it joins the River Colne.

A spokeswoman for Thames Water said: “We believe the sewage has come from a nearby commercial property whose foul sewer has incorrectly been connected to the surface water drain, which flows directly into the watercourse.

“We’re working with the property owner to confirm this and in the meantime are keeping a close eye on the river and cleaning up when needed.”

When questioned further about the blunder, she refused to disclose which commercial property was the culprit, or the type of business.

But the spokeswoman said that Thames Water has a “whole team dedicated to tracing these misconnections to try and prevent these types of problems”.

Once a misconnection has been traced, the Environment Agency takes the issue up with the property owner who is responsible.

Green Party district councillor Simon Grover said he hoped the authorities would stop such pollution from recurring.

He added: “The Ver is a rare chalk stream of worldwide significance, and home to a huge range of wildlife.

“It is also a jewel in St Albans’ crown, treasured by residents and visitors. So it’s astonishing that a commercial premises could have polluted our river in this way, right in the heart of the city.”