A farmer was left gobsmacked after a river turned a garish "smurf blue" - leaving children and dog walkers terrified of the water.

Elliot Wollen, 31, woke up on Sunday to find the discoloured waterway with a blue substance pouring from a storm drain.

He said the odourless colouring - believed to be ink - drifted 300 metres downstream and approached a popular fishing spot half a mile away.

Now, dog walkers and young families who frequent the stream, which backs onto a housing estate, are steering well clear of the potentially polluted water.

Elliot, who manages a local community farm by the river in Harlow, said: "It's a really vivid smurf blue.

"As it washed downstream it caused the whole of the brook to turn blue.

"There's no doubt that this is polluting the waterways.

"We're concerned about human and animal health and the wider environment.

"It's a very popular part of the river. People walk their dogs and children play in it. We use it for our crops at the farm.

"No one is thinking 'that looks nice and inviting'."

The Environment Agency said there's no evidence of harm to wildlife or humans but Elliot said it's not the first time the brook has changed colour, with it previously turning bright pink and red.

Elliot pointed the finger at a neighbouring industrial estate with a storm drain leading into the stream. He said the "pollution" happens every Sunday.

He claimed that Environment Agency officials have ignored 15 complaints about the waterway over the last two years.

Elliot said: "No one knows what this substance is and we're just being ignored.

"Every Sunday morning someone is washing this substance down the drain.

"Our neighbour said this has been happening for two years and he's reported it to the Environment Agency 15 times."

Echo: Elliot Wollen, 31, woke up on Sunday to find the discoloured waterway with a blue substance pouring from a storm drainElliot Wollen, 31, woke up on Sunday to find the discoloured waterway with a blue substance pouring from a storm drain

"People have got pictures of it pink, red and white.

"Hopefully they [the culprit] will be prosecuted and they'll have to pay for any damage.

"People in Harlow won't stand for it, they're outraged."

There is no evidence of harm to wildlife or humans due to the substance but Elliot is concerned that it could pose a cancer risk.

He said: "Even if it's ink, it's potentially got carcinogenic qualities."

Elliot has taken a sample of the discoloured water, most of which has now dissolved into the river, to be tested at a local lab.

Environment bosses refuted claims they ignored concerns about the waterway and said they are now investigating the discolouring.

An Environment Agency spokesperson said: “Our specialist officers have visited and are investigating how Canons Brook in Harlow turned blue over the weekend, but thankfully have no current evidence of harm to wildlife or the environment.

“If members of the public have information that might help our investigation, or suspect pollution in any rivers or streams, they should contact our incident hotline on 0800 807060.”

Essex Police confirmed it had received a report about the suspected pollution and added that the Environment Agency will lead an investigation.