From Aer Arann's terms and conditions
"10.2 AIRPORT CHARGES
In the case of passengers departing from Waterford Airport, a EUR €5 airport development fee is payable on departure.
In the case of passengers departing from Kerry Airport, an airport development fee of EUR €6 payable at the time of booking and is included in the fare.
In the case of passengers departing from Newquay airport, an airport development fee of GBP £5 is payable on departure."
The development charge has being in place in waterford a good while now