Nothernsky - illuminating. Precisely the reason I started this thread, so colleagues/fellow aviators could become safer.
Mutt - I am not sure, but here are a variety of places - Appch Plates, State/Airport authorities, topographical charts, Jepp's database? Municipalities around the airport, etc.
Basically, if one really wants, go out there and find out the best you can. If you believe you have, create the EOSID/ET. If you come across a newly erected obstacle, revise the EOSID immediately and NOTAM it.