An almighty row is brewing on Britain's rivers. This month, the Environment Agency released a report that it claims guarantees improved rights of access to those who swim in, paddle on or simply walk alongside inland waterways in the UK.

The report, A Better Place to Play, took two years to compile. Its critics are less than impressed with the fact that new access rights will allow the public on to an additional 45 of the 40,000 or so miles of Britain's river systems.

"It's a joke," says Tamsin Phipps of the British Canoe Union, the watersports body whose Rivers Access Campaign is at the forefront of calls for change. The BCU also claim that on the four rivers where new rights have been granted (the Waveney, Mersey, Wear and Teme) access agreements have, in some cases, been in place for some time.

In Scotland, access to rivers and waterways falls under the Land Reform Act, legislation passed as recently as 2003, which made law the public's right to roam on waterways. In England and Wales, the legal entitlement of recreational river users is much less clear. The Countryside and Rights of Way Act (Crow) of 2000, for example, grants a limited right to roam but does not apply to rivers.

"The laws of navigation in England and Wales can be traced back to William the Conqueror," says Ms Phipps. "Invariably, those rights were granted to whoever owned the land, and the laws desperately need updating. A number of political parties in the Welsh Assembly are including waterway access in their manifestos for next year [when a general election is due to be held], and there is a danger that England could be left out in the cold."

She says that in England and Wales a "public right of navigation" exists on just 4 per cent of "navigable waterways", those with channels of 10 feet or wider.

Unsurprisingly, not everyone shares the BCU's sense of injustice. "If you have a legal right of access, that then entitles you to override the rights of other sports and interests," says Caroline Bedell, national access adviser for the Country Land and Business Association (CLA), which works in the interests of landowners in England and Wales.

"In Scotland, where a blanket right to roam policy now exists, there has, in some areas, been significant damage to the fishing industry through the arrival of whitewater rafting," she says. Ms Bedell, a Crow specialist, also points to the fact that despite about £70m being spent on developing right-to-roam legislation in England uptake by the public has been limited.

The Government seems to agree. In a written answer to Parliament last week, Barry Gardiner, under-secretary for the environment said: "The Government have ... no plans to provide a statutory right of access to water, since research has shown that overall supply is roughly in balance with demand."

Ms Phipps would be likely to disagree. "The BCU currently has a membership of around 60,000," she says, "but the total number of recreational canoeists is closer to 1.5m. More of those would become BCU members if we could get more access."

Ms Bedell believes there is a feeling among some landowners that the BCU has not "engaged in the process" of developing legislation, preferring instead to slight those advances that are made. It is a charge that Ms Phipps denies. "In 2004, we met with the [then] Environment Minister, Alun Michael, and agreed to work together on the access problem. Since then we've barely been consulted."

So what next? A "mass paddle" to Westminster in protest over the report is planned for early next year, as is a Private Member's Bill. "This Government talks a lot about trying to encourage people into the countryside," says Ms Phipps, "but where our waterways are concerned, almost the opposite is true."