I am not familiar with the area, but a quick scan of FCC records indicates that one of the following could be the input for the sheriff:
154.725
155.475
155.850
155.970
Fire will possibly be:
150.775
154.280
154.385
159.075
You will obviously not hear anything unless you are right on top of the unit but again this is a start. FCC database records for these users seems to be up to date.
Cheers