A wildlife expert has called for Sussex’s chalk waterways to be given legal protection to safeguard their future.

More than 50 chalk streams carry and help to filter about 70% of the county’s drinking water.

However, a World Wide Fund for Nature (WWF) report found that only 20% of the waterways were in good condition and streams were failing to meet “good ecological status”.

WWF is now calling on the Government to take urgent action.

Fran Southgate, wetlands officer for the Sussex Wildlife Trust, based at Henfield, said the streams should be given Sites of Special Scientific Interest protection by Natural England.

She said: “These streams are an important part of our cultural and natural heritage. Although we have lost some, there are many more that we can help to restore and protect.

“We also want to raise awareness of just how important these streams are.

“Most rivers and waterways in Sussex are made up of silt, clay and mud, but these unique streams are made of chalk, which is alkaline.

“The clean water which feeds them from the chalk springs results in some of the purest water you can find.

“And because this chalk environment is so different, we find unique and rare species in chalk streams that you would not find anywhere else.”

A combination of invasive species, development, pollution, water abstraction and impacts of historic industry, have damaged many of the waterways beyond repair.

Between 2010 and 2012 a chalk stream expert called for 20 of the streams in Sussex to be given legal protection.

But other than being in the National Park, many are yet to receive any extra protection.

The South Downs National Park Authority is also working on preserving chalk streams.

Chris Manning, from the authority, said: “Chalk streams support rich wildlife and research shows that the Sussex part of the National Park contains some of the finest head-water chalk streams in the country.”