Hiya! Welcome to WARSUG, glad you found us
This document is a couple of years old now and may not be absolutely up to date, but it shows the WAERN (WA Emergency Radio Network I think it stands for) channels and frequencies: warsug/frequencies/WARSUG%20-%20WAERN%20freqs.pdf
Looking at that, you might want to check out channels 186 and 187 (162.5375 MHz and 163.8875 MHz), then channel 282 (162.1500 MHz) and 616 (162.8375 MHz). There may well be others that are used too but it should give you a good starting point.
(By the way that document was in the DFES/DPaW section in a sticky'd thread called "The one-stop shop for DFES information" which has other stuff too that might be of use...)