Activists are planning nine mass trespasses along rivers to highlight landowners who are blocking public access to the nation’s waterways.
The Right to Roam campaign said 96% of waterways in England and Wales lack a clear right of navigation.
Campaigners told how the River Dart, in Devon, has 108 separate landowners – making it “nigh-on impossible” for Ministers to negotiate permissive access agreements with all of them.
Nadia Shaikh, from the Right to Roam campaign, said: “Rivers are the lifeblood that flows through all of our communities – they should be places where everyone can swim, paddle or walk in nature. Yet landowners have locked the public out, cutting off access to these magical places.”
Labour’s election manifesto promised to “create nine new national river walks, one in each region of England”.
But campaigners said the pledge is “unworkable and inadequate”.
Guy Shrubsole, from Right to Roam, added: “There are hundreds of rivers in England, so pledging to create walks along just nine of them is peanuts – why not give every community the right to access and care for their local river?
“After all, the Government and landowners need the public’s help to look after rivers – it’s been swimmers, kayakers and anglers who have raised the alarm about river pollution.
“Let’s end this feudal idea of needing the landowner’s permission to visit your local river, and create a right of responsible access to the countryside, so that everyone can enjoy and protect our rivers.”
A Defra spokesman said: “Our countryside and green spaces are a source of great national pride, but too many people across the country have been left without access to the great outdoors.
“We are increasing access to nature and the countryside, creating nine new National River Walks, three new national forests and the 2700-mile King Charles III England Coast Path is also nearing completion.”