Cwm Ivy: Where the sea comes in

Aerial view of Cwm Ivy marsh

Cwm Ivy marsh is a small parcel of land on the coast of North Gower. It was claimed from the sea to be used as farmland in the 17th Century and was protected by a sea defence which over the years increased in size and strength. Now after nearly 400 years as farmland the landscape is changing and the sea is moving back in.

It is a decade since the National Trust released its seminal ‘Shifting Shores’ report which held one clear message ….. as a nation we can no longer build our way out of trouble on the coast. This means at sites such as Cwm Ivy we no longer try to defy nature by holding back the tide but allow as natural a process as possible to take place.

The challenges

In November 2013, Cwm Ivy sea wall was showing signs of distress. Repeated heavy rain had swelled the inland stream to unprecedented levels and the sluice gate designed to drain the marsh simply wasn’t able to remove water fast enough. The pressure of water forced a small hole under the wall and the following winter of storms, rain, high tides and storm surges began to widen the hole and allow significant amount of sea water in to the fresh water marsh. It wasn’t until August 2014 however that the wall eventually had a catastrophic failure and effectively ended its time as a ‘sea defence’.

Looking forward

Thanks to the vision of the shifting shores document of allowing coastal realignment to happen as naturally as possible we are now spending our efforts not on maintaining the defence but working to improve the current situation of the footpath being impassable and managing the change in habitats from freshwater marsh to saltmarsh.


Almost as soon as the breach occurred the plants on the marsh underwent a radicle change. The farmland grasses died back within days and the trees rapidly began dropping leaves and most were standing dead wood by spring 2015. Was this a problem? Visually this was not an improvement over the lush greens we used to see when it was a fresh water habitat. However this transition, as unsightly as it was, was temporary and once the saltmarsh plants started to take a hold Cwm Ivy Marsh began its stunning transformation into a wildlife rich saltmarsh.


Also, standing dead wood is a very rare and important habitat in Wales. As humans have increasingly organised and ‘tidied’ the countryside so we have reduced and removed marginal habitats like these. Standing deadwood is essential for birds such as wood peckers to feed on and they are superb habitat for a whole host of invertebrates.


Fast forward a few months to late March 2015, and the first signs of life from the salt marsh plants could be seen. English Scurvey grass was the first to show itself but this was quickly followed by salicornia species, sea blight, thrift and sea spurrey.  By the June, the whole marsh was alive with the vibrant greens of a healthy saltmarsh.


Aside from the saltmarsh plants we have also seen a huge increase in activity from otters and kingfishers in the marsh as the receding tide leaves behind pools full of fish – easy pickings for these impressive predators.  We are currently erecting the second of our two new bird hides overlooking the marsh and over the winter will be doing some work to improve the footpaths and signage around the area.