A Harrogate conservationist has called for signs to be put up urging children and dogs to avoid entering Oak Beck.
Keith Wilkinson described the situation as “desperate” after a series of incidents over the last fortnight have seen the beck turn brown.
The Environment Agency said last week it was “investigating the possible source of the pollution” after receiving “a number of reports of discoloured water”.
But after a brief recovery, the beck was heavily discoloured again today.

Oak Beck in Jennyfields this morning
Mr Wilkinson, who is honorary secretary of Bilton Conservation Group and chairman of the Nidd Gorge Advisory Partnership, said:
“The Oak Beck situation is desperate with daily pollution events for two weeks now — sand and silt from construction work, solids escaping from the open storm drain near The Hydro and a constant stream of what looks like detergent foam from high up near Birk Crag.
“It is totally unacceptable. Signs are needed urgently to warn children and dogs to keep out of the water.”
An Environment Agency spokesperson said:
“At the moment as investigations are currently ongoing so we are unable to comment further in order not to prejudice our enquiries.”