West Yorkshire Fire and Rescue Authority has been forced to shell out more than £1.3m to cover strike-breaking shifts 47 times since industrial action began in September last year.
The warning comes just days after the Fire Brigades Union announced it will hold a 24-hour strike on December 9 in an on-going row over pensions.
They fear firefighters will be forced to work until they are 60 instead of 55 and they claim they will receive lower pensions.
A report to the authority’s Community Safety Committee reveals the service received 1,509 emergency calls while union members were striking.
The authority has confirmed there was “no lessening” of their response as a consequence of industrial action.
The report, which will be discussed tomorrow, said the ongoing impact of action short of strike has been “felt” across the organisation.
Assistant chief fire officer Dave Walton said: “The announcement of the 48th period of strike action in this long running and damaging dispute is something that no one would have predicted when the strikes started in September 2013. We now face a second consecutive festive period with the threat of strikes hanging over the service and its staff.
“Having endured strike upon strike at a cost to date of £1.3m so far and with no end in sight.
“We wonder when a resolution will come?
“The unquantifiable costs of damage to staff morale and the reputation of this service in the eyes of the community which we serve continue to build.
“The time is long overdue for those who can solve this long running dispute to do so and to prevent further loss and possible tragedy.
“The service and its staff can then focus upon continuing to deliver an excellent fire and rescue service to West Yorkshire.”