Hello, 

I work in a very large company and was wondering if it was possible to set up Lync 2013 in a way such that I appeared "available" to the members of my department while appearing offline or "busy" to the rest of the various workers? If it is possible how might I go about doing this?

Thanks

That is not possible with Lync or Skype for Business unfortunately.  Your presence is an aggregate of presence states from all logged in endpoints and will be presented to all users similarly.  Some may see more detail than others "In a meeting" vs "Busy", but otherwise this is not configurable.

Hi,

The presence can't be viewed different by different Lync users, if you don't want someone view the presence or contact to you, you can only block this user.

Best Regards,
Eason Huang