Reported in the Guardian, pollution from treated and untreated sewage is the greatest threat to river biodiversity, causing more damage than runoff from farms, according to research.

There is a need for more regulation of water companies and improvements at their treatment plans to protect rivers, say the authors of the study.

The research from the University of Oxford was released on World Rivers Day. No river in England passes tests for chemical or biological pollution, and government targets to improve the water quality in rivers will not be met.

“Improvements to wastewater plants should be implemented along with more regulations. These efforts are crucial in safeguarding the integrity and safety of our rivers – fundamental elements of both ecosystems and human wellbeing,” said the lead author, Dr Dania Albini, of Oxford’s biology department.

Treated sewage released by water companies into rivers and raw effluent that is dumped in rivers via storm overflows is the primary driver of increased nutrients, algae and sewage fungus in rivers, according to the study.

Sewage discharge radically alters plant, animal and microbe communities and increases the abundance of harmful species. While runoff from farmland has negative impacts on river water quality, the research reveals that sewage discharge into rivers has a greater impact on water quality and the animals and plants that live in rivers.

The findings were published in the journals Global Change Biology and Ecological Solutions and Evidence.