People have been warned against swimming in the River Ure or River Ouse, as Environment Agency officers investigate higher levels of ammonia.

Villagers in Marton-cum-Grafton, North Yorkshire, smelled ammonia in Goker Beck and noticed the water had gone black.

It is thought to originate from a breached bund of a slurry pit. Ammonia is a chemical used to produce fertiliser and can hurt skin, eyes and lungs.

An Environment Agency spokesperson said: “Our officers have been on site monitoring elevated ammonia levels in the River Ouse and working hard to identify the source of the pollution. We will not hesitate to take enforcement action if appropriate.”

The River Ure flowing under Masham Bridge. Photographed by Yorkshire Post photographer Jonathan Gawthorpe.

placeholder image — The River Ure flowing under Masham Bridge. Photographed by Yorkshire Post photographer Jonathan Gawthorpe.

North Yorkshire councillor Arnold Warneken called on members of the public to avoid swimming in the rivers due to the incident.

He said: “It’s devastating for wildlife, livestock and our whole community that such a big pollution event has taken place.

“I would strongly advise residents or their pets to avoid entering any beck or river in the wider area until the extent of damage is established.

“It’s a lovely time of year and the sun’s shining, but please make sure that your pets, children and young people celebrating exams all keep out of the water."

Yorkshire Water said that the incident had led to low water pressure in the Easingwold area during the week, as the Ouse is one of the firm’s drinking water extraction points.

While all residents retained some water, Yorkshire Water distributed bottled water to those affected. The supply has since resumed.

A spokesperson said: “The pollution incident affecting the Ouse, caused by a third party, had an impact on the raw water we use in the Easingwold and Tollerton areas.

“To protect the quality of the water we supply to customers, we took the precautionary step of temporarily shutting down our water treatment works.

“Our treatment works were back up and running quickly and water quality met our high standards throughout, despite some customers experiencing lower water pressure at times."