Sir, – I was disconcerted to read the remarks of "an Irish Water spokesman" regarding the Ectocarpus algal deposits that have been washing up along the shore of Sandymount Strand for several months now (News, November 20th).
The comment that these deposits were caused by “naturally occurring algae” and that “there wasn’t a wastewater issue” represents a serious oversimplification in relation to the eutrophication (nutrient enrichment) of the waters of Dublin Bay as a consequence of the discharges into the bay from the Ringsend waste water treatment plant.
During periods of substantial rainfall, the treatment plant, which is operating far above its design capacity, is frequently incapable of processing the volume of waste water that it receives. This water includes sewage, and the plant discharges the waste that exceeds its capacity into the bay from temporary holding ponds.
As swimmers will be aware, quite frequently following rainfall events, the water quality in Dublin Bay is such as to render swimming unsafe for several days.
These relatively frequent discharges raise the nutrient status of the waters of Dublin Bay, causing a bloom of the Ectocarpus algae.
While it is certainly an error to identify the decaying algal mats as raw sewage discharged from the treatment plant, it is nonetheless misleading to indicate that these deposits are simply a natural phenomenon that is unconnected with the discharges from the plant into Dublin Bay.
– Yours, etc,
MARY CARVILL,
Sandymount,
Dublin 4.