Conservationists and angling organisations have settled their High Court dispute with the government over their accusation that it is failing to take effective action to protect waterways from agricultural pollution.

WWF-UK, the Angling Trust and Fish Legal claimed a 'legal victory' after receiving courtroom reassurances that mandatory water protection zones (WPZs) are being actively considered alongside voluntary steps by farmers to reduce pollution in rivers and wetlands.

They had accused Defra and the Environment Agency of unlawfully keeping WPZs, which can include criminal sanctions for breaches, 'on the back burner as a last resort'.

The accusations were denied, and lawyers for environment secretary Elizabeth Truss – who is also the MP for South West Norfolk – said WPZs were already under consideration and were not subject to 'a last resort doctrine'.

The judge, Mr Justice Collins, urged both sides to settle the legal action. It was withdrawn after a two-page 'position statement' was agreed by both sides beginning with the words: 'It is not true that the secretary of state and Environment Agency does not intend to apply WPZs.' The statement also made it clear they were not being regarded as a last resort.

WWF-UK and the angling organisations said in a statement: 'As a result of the legal victory today (Thursday), the government must evaluate the use of mandatory water protection zones alongside voluntary steps by farmers, which have so far failed to protect these vulnerable places from farm pollution.'

Mark Lloyd, chief executive of the Angling Trust and Fish Legal, added: 'This is a clear message to government that they must stop dragging their feet and they must now take the necessary steps to improve the health of these precious rivers and wetlands.'

A Defra spokesman said: 'We are pleased to have reached agreement in this case and we will continue to consider how we use water protection zones as one of the ways to protect our most treasured conservation areas.

'Rivers in England are the healthiest they have been for 20 years and we are committed to working closely with the farming community and environmental groups to further improve water quality.'

Treasured waterways

The case focused on areas known as Natura 2000 sites, including several East Anglian habitats where the campaigners blame poor land management for causing soils, carrying nutrients and pesticides, to wash into the waterways, harming fish and other wildlife.

Among the protected sites listed is the River Wensum, which is an essential habitat for species such as water voles, white-clawed crayfish, kingfisher, brown trout, eels and otters.

The Broads are Britain's largest protected wetland and are home to wildlife including great crested grebe, grey heron, marsh harrier, cormorant, bittern, Norfolk hawker dragonfly and the swallowtail butterfly

The headwaters of the Little Ouse and Waveney valleys hold some of the UK's most precious fens, which are internationally important for rarities such as sundew, bogbean, grass of Parnassus and great raft spider.

In the heart of The Fens, the Ouse Washes is a large area of grazing pasture that floods in the winter, attracting thousands of ducks and swans, while hundreds of snipe, lapwings and redshanks breed in the spring.