"Mike" - I believe you are referring to Baker Mountain County Park (owned by Catawba Co). South Mountains State Park may be the closest state park to that area.
DHS grants were used by Catawba County to survey the property on Bakers Mountain, as well as to rebuild or replace towers at a couple of county locations (Anderson Mountain, Riverbend). Some of the work was related to the county's participation in the Piedmont Area Communications Council's 11-county interoperability plan.
It might be my imagination, but I think I've seen DHS warning signs at some locations were airnav radio equipment is located, and they may be placing similar signage at other radio sites.
Mention of the Bakers Mountain project is made in a 2007 county Information Technology Center goals and objectives report.
I've never heard any FBI or Customs channels that I could determine were transmitting off the Bakers Mountain site.
SBI agents had access to the WRC repeaters. I think I remember that there was a WRC radio site on Bakers Mountain. Audio from the site was fed down to the Newton NCHP tower via 2GHz, then onto the NCHP Pores Knob site via 955 MHz multiplexing, which tied into the state's microwave backbone.