The question is rather poorly worded; Yes, insofar as the RRDB has it, BelAir is on the Harford county system (I don't live there, so I can't verify whether it's active or not...). No other barracks have a talkgroup on the Harford system AFAIK, and yes, fourwd1 is correct - many barracks are getting portables so they can call in on their county's 800 system.
Hearing MSP is something of a challenge; a typical duckie just isn't going to cut it - you need a decent antenna to hear them as, for the most part, their 39 mhz operations are all simplex in nature. They do use low power repeaters, but they're just as difficult to hear.
73s Mike