One of the UK’s most precious wetland landscapes is under threat from the Welsh Government's road building plans

If the proposed M4 extension goes ahead, it will fatally undermine the Welsh Government’s commitment to make sustainable development their central organising principle.


The Gwent Levels

The Gwent Levels are one of the largest surviving areas of ancient grazing marsh and drainage ditch systems, known as reens, in Britain.  It is extremely rich in wildlife including otters, wading birds and many rare plants and insects. 

The Gwent Levels is comparable to other iconic wetlands such as the Somerset Levels and Norfolk Broads 

A reen on the Gwent Levels

Proposed M4 extension

Known as the M4 relief road, the proposed new motorway-grade road is one of four options currently being considered by the Welsh Government to help manage congestion north of Newport on the M4. 

The Wildlife Trusts believe that building extra road capacity is not justified as:

  1. Traffic levels on the M4 around Newport have fallen below their peak in 2004
  2. There are cheaper and less damaging options including integrated traffic management, investment in sustainable transport and improvements to junctions and alternative routes
  3. The estimated £830 million cost of the M4 relief road cost would be a significant burden on public expenditure in Wales for many years to come

The Gwent Levels provides benefits such as flood prevention, water management, recreation and tourism estimated to be worth over £60 million a year

In addition to direct loss of habitat, the new road would create a barrier preventing the movement of wildlife and impede water movement which could have a significant effect on the wetland habitat. There is also potential for indirect negative impacts on the internationally important Severn Estuary.

The road would cut through four nationally important Sites of Special Scientific Interest (SSSI): 

  • Redwick & Llandevenny
  • Whitson
  • Nash & Goldcliff
  • St Brides

The road would also cross the internationally important River Usk Special Area of Conservation (SAC) and pass close to:

  • Magor Marsh SSSI
  • Newport Wetlands SSSI and National Nature Reserve. 


Explore the Gwent Levels

Virtual tour by Mike McFarlane

360 view


Wildlife under threat

The Gwent Levels is nationally important for its wildlife and especially for the rare aquatic invertebrate assemblages and wetland plants found in the network of reens across the area, some of which date back to Roman times.

Some of the wildlife found on the Levels includes:

  • otters and water voles
  • breeding waders - lapwing, snipe, redshank and curlew all breed locally across the Levels
  • 144 Nationally Notable or Red Data Book invertebrate species (including water beetles and dragonflies) have been recorded from the Gwent Levels
  • the nationally scarce rootless duckweed (Wolffia arrhiza) - considered to be the world’s smallest flowering plant and occurs nowhere else in Wales.

What is The Wildlife Trusts' vision for the Gwent Levels?

The Gwent Wildlife Trust is working to restore and recreate habitats for wildlife on the Gwent Levels and reconnect people with nature.  Its flagship nature reserve at Magor Marsh lies on the eastern edge of the Gwent Levels.  Over the last three years, the Magor Marsh Centre has hosted over 6000 children on educational visits.  The Trust also has a nature reserve at Solutia Meadows.

Gwent Wildlife Trust is a lead partner in the Campaign Against Levels Motorway (CALM), an alliance of organisations, community councils and individuals opposing major road building on the levels.

CALM - Campaign Against the Levels Motorway


FilenameFile size
gwent_levels_m4_relief_road_briefing_final.pdf220.96 KB
gwent_levels_map_with_impacts_of_m4_extension.pdf818.69 KB