To expand on what "Nawton" posted above me, Nassau is currently using the P25 system to communicate, and all of the talk groups are encrypted.
As long as the patches are setup, you will be able to hear Nassau PD unencrypted through their old UHF Frequencies.
The UHF Repeaters are no longer being maintained like they were the primary method of communicating, so don't be surprised when the repeaters go down.
The Countywide 2 and 4 frequencies are no longer in use, and neither are any of the Tactical Channels like Tac-10. The same holds true for the BSO frequencies. The Highway / Esu / K9 frequency is using lower power, and the 1st and 7th machine has hardware faults that take it off line for days, and sometimes weeks. There are more talk groups for the police to use than there were frequencies, so sometimes you will hear them request units switch to the "detail" or "admin" channel. There is no mapping of those on conventional frequencies.
PD has the ability to shut down the simulcast at a moment's notices.