Image source, Matt Staniek Image caption, The Environment Agency says the increased presence of blue-green algae is a powerful "indicator of change
Campaigners say raw sewage dumped in Windermere has made the water quality so bad that the lake is in danger of becoming "ecologically dead ".
Curator Matt Staniek said that the sewage came from th The overflow system of the water treatment site andprivate septic tanks "largely unregulated ".
"It 's in a very, very serious condition and it will only get worse," he said.
Water company United Utilities (UU) said the overflow system was used in heavy rains to prevent flooding.
It said it has invested £ 40million in its processes around Windermere, improving the quality of the wastewater.
But Mr Staniek said the sewage entering the lake caused a bloom of blue-green algae, which was killing invertebrates, fish and vegetation.
"Something needs to be done now before the lake becomes an ecologically dead body of water in the heart of the national park," he said.
Legend of the 'image, Matt Staniek has started a petition to improve Windermere ' s water quality
The Environment Agency (EA), which is responsible for enforcing water regulations, said the issues were "complex ".
Environmental, Planning and Environmental Officer engagement, Jim Ratcliffe, said the agency had been working with UU since the end of the90s "demanding gradual improvements to their wastewater treatment processes ".
"Regarding the main treatment processes and the effluents discharged into the lake, we have found tremendous improvements over these two decades, ”he said.
“ The challenge is that the lakes in particular take a long time to recover. ”
The EA looked at the company's storm releases to see "where improvements need to be made," he said.
'Strongest indicator '
It also looks at local agriculture and private property.
"Our preference would be that we don't have direct discharges into streams, rivers, anything like that, "he said.
The increased frequency of blue-green algae was " the strongest indicator of change "but was magnified by climate change, he said. he says.
Image source, Matt Staniek Image caption, Sewage disposal in backyards is permitted. 'water in specific circumstances
Water companies are at thetorised to use storm overflows under certain conditions to prevent sewage from flooding homes and roads.
The EA is only able to investigate if releases occur outside of these conditions.
M. Staniek has started a petition calling for better regulation and higher water standards.
A separate petition on Parliament's website calling for a ban on water companies from dumping raw sewage in rivers has passed the 100,000 signatures required for it to be debated by MEPs.
Image source, Matt Staniek Image caption, Mr. Staniek said he saw dead or dying fish, invertebrates and vegetation
Follow Hfrance.fr North East & Cumbria on Twitter , Facebook and Instagram . Submityour ideas for articles at .