Welcome to the forums,
There's actually quite a few people who scan in Castle Rock (I recently moved from that location). Sadly your scanner will not handle Digital (P25) audio as the above have said.
Scanners that will handle the system (and are not cheap) include:
and a few older models.
If it's any help to you, you can still listen to Douglas County Fire Dispatch as they dispatch for the 150s (Castle Rock Fire Department). They simulcast their main dispatch on 151.115 MHz analog. With that setup, however, you will not be able to hear any of the operation channels that they tend to switch to.
If you just purchased your scanner, I would recommend you return it and get a scanner that can handle DTRS if it it within your price range.
Last edited by Spitfire8520; 09-27-2012 at 10:54 AM..