Fish weirs work by guiding fish into a confined trap or enclosure as the tide retreats, a method requiring both a sound knowledge of local water movement and the labour to drive posts into soft ground and maintain the structure against the pull of currents and the slow assault of decay. That this alignment has survived at all, even partially, owes much to the preserving qualities of waterlogged estuarine clay.

The structure is classified as post-medieval in date, placing it broadly after the sixteenth century, a period when fish weirs of this kind were widespread features of Irish coastal and estuarine life, often contested by landowners and fishing communities alike. The site was recorded and described by archaeologist Aidan O'Sullivan, whose 2001 survey of intertidal archaeology along the Shannon estuary brought a number of such features to wider attention. The sixty-metre post alignment at Newtown is one of several such structures documented along this stretch, each representing a local fishing economy that has long since disappeared from the landscape above the waterline.

The posts are exposed only at low tide, so timing matters considerably if you want to see anything at all. The foreshore here is soft underfoot, and estuarine mud has a way of making progress slow and footwear decisions consequential. The alignment runs through the upper foreshore, meaning you do not need to venture far from dry ground, but the clay surface shifts in consistency depending on recent weather and the state of the tide. What you are looking for is a relatively regular spacing of dark, weathered timber stubs protruding from the grey-brown mud; easy to walk past if you are not already aware of what to expect.