Why is Dublin Bay so murky?

Sir, – The murkiness of Dublin Bay is clearly not a recent phenomenon. Even I, as a non-Irish speaker, know that the name Dublin is derived from the Irish for black (dubh) and pool or mire (linn).

If the area had been clean, citizens of the capital would not now be known as Dubliners and James Joyce would have written a different book. – Yours, etc,

KEVIN O’SULLIVAN,