Booterstown marsh

Booterstown Marsh, a Nature Reserve, is located in Booterstown, County Dublin, between the coastal railway line and the Rock Road. It is an area of salt marsh and muds, with brackish water. It includes the only salt marsh, and the only bird sanctuary, in south Dublin Bay. It lies just outside the boundary of Dublin city, and just north of Booterstown DART station and its car park.

The marsh belongs to the residual Pembroke Estate, and An Taisce administer it, having acquired a lease in 1970-1971 and having designated it a bird sanctuary. It is part of both a proposed NHA and a proposed SAC, and of the South Dublin Bay and River Tolka Estuary Special Protection Area (SPA).

The marsh covers an area of approximately 4.3 ha. It is fed with fresh water from the Nutley Stream. This is occasionally supplemented from the Trimleston (or St. Helen's) Stream, which runs in a raised box culvert at the city end of the marsh. At the southern end the Nutley leaves the marsh and passes under the entrance to Booterstown DART station, reemerging into a channel, Williamstown Lagoon or Creek, which runs south for some distance and then flows east to the sea under the railway embankment. Some salt water flow reaches the marsh from this channel at each rising of the tide (the amount of salt water flow is limited by the passage at the railway station).

The marsh contains two low-lying mud islands, made to provide secure resting and roosting areas for birds. These were formed in 2006.

Originally the area now occupied by Booterstown Marsh was open to Merrion Strand and was part of a fringe marsh from Dublin city to Blackrock. Over time, much of this marshland was lost due to reclamation. The current marsh resulted from the building of the Dublin and Kingstown (now Dún Laoghaire) railway line, which was one of the first in the world, from 1834-35. The line was built on an embankment, protected by a granite seawall. In the 1830s, the resulting tidal lagoon covered more than 28 ha. In the following decades much of the area was filled in (part of it now forming Blackrock Park), leaving only Booterstown marsh still subject to flooding by seawater at high tide.

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