ENGLAND'S chalk streams have suffered a “decade of decline," campaigners warned today as they called for more action to protect the globally rare habitat.

Chalk streams are rare, clear, slow-flowing rivers that are fed from underground chalk aquifers and springs. There are only about 200 in the world, with 85 per cent of them in England.

Monitoring five sites at the River Avon over the last decade, conservation charity WildFish discovered a significant decline in wildlife such as freshwater shrimps, mayflies, caddisflies, beetles and aquatic bugs.

The monitoring, carried out in partnership with the Wiltshire Fishery Association, revealed that the number of invertebrates had plummeted by more than 77 per cent during annual counts between 2015 and 2024, while diversity fell by 17 per cent.

The situation for riverflies was even worse, having fallen by 83 per cent in 10 years.

Assessments carried out under the statutory water framework directive found that all the sites monitored by WildFish scored as high or good quality for invertebrates in 2024, even though their population had plunged by three-quarters.

WildFish said the statutory standards set the bar too low to reflect the high levels of invertebrate life that a healthy chalk stream should support.

As a result, the official monitoring can conclude all is well in the river despite major declines in key species, and make action and investment to protect them more difficult, it said.

Dr Janina Gray, head of science and policy at WildFish, warned that chalk streams are suffering from “death by a million cuts.”

She said: “The Avon is a SAC (Special Areas of Conservation), it’s the most protected river we have, and yet the abundance drops that we’re seeing are dramatic in that time period.

“It just shows that the bar is not set high enough to properly protect chalk streams.

“We would like the Environment Agency and Natural England to revise the standards for chalk streams to raise the bar to protect them.”

The Department for Environment, Food and Rural Affairs (Defra) said: “Within this new government, our top priority is to clean Britain’s rivers and restore them from years of damage.

“Chalk stream restoration is a vital part of this effort.

“We have secured £2 billion of funding from water companies to start cleaning them, while modernising the abstraction licensing system to ensure water is used sustainably and to stop damaging abstraction practises to the environment — a problem particularly pronounced in chalk streams.”