Eighty metres long and oriented roughly north to south, the structure is not immediately legible as anything in particular to a casual observer, but it is the remnant of a fish weir, a form of trap in which posts and woven or braced panels were arranged to funnel fish into an enclosed space as the tide fell, leaving them stranded and easy to collect.

The weir dates from the post-medieval period, meaning broadly after the sixteenth century, though the technology itself is ancient and examples survive across Irish estuaries from prehistoric times onward. What distinguishes this particular structure, documented by Aidan O'Sullivan in 2001, is the two lines of obliquely set bracing that cross the creek at angles, a configuration that would have reinforced the main post alignment against the considerable push of tidal water in the Shannon. The estuary here is wide and tidal movement is substantial, so the engineering reflects practical necessity rather than any unusual sophistication. The weir intersects with a neighbouring feature on Bush Island, suggesting this part of the foreshore was used with some intensity for inshore fishing at some point during the post-medieval centuries.