Hello. I did see the two FCC licenses you mentioned:
KB90022
COLORADO, STATE OF
WPFA849
POTOMAC APPALACHIAN TRIAL CLUB
Usually 166.90 in the past was allocated to Land Management Bureau and National Park Service.
I found this at another RR Web page:
National Park Service 166.9 FB2 166.3 VA Shenandoah Park, VA
National Park Service 166.9 FB2 166.3 Long Island, NY Fire Island
So maybe you're hearing the second one?