Your point is taken. For the record, I never implied the OHS was responsible for any project attempting to "hide' anything. If anything, the OHS, and any state historical society for that matter, does its best to preserve our historical artifacts and sites, often with limited resources. I wish to add the efforts of museums and tireless archeologists and historians.
As for flooding by dam projects and lakes, there are numerous cases of irreplacable and priceless sculptures, mosaics, architecture, and other artifacts buried by rising waters. Once again, all that would not happen without three things: politics, money, and decisions.