bell47,
thompy is correct about the quality of the trees being pulled out of Lake Superior. There is a Discovery Channel documentary a few years ago on excavating old grow trees from rivers and lakes. Expensive endeavor to extract the dead heads/snags from the bottom, but by all accounts it is worth the investment if you are going to use the resulting lumber for the manufacture of high-end furniture and/or musical instruments. According to the Discovery documentary, a company was attempting to duplicate a Stradivaius violin or cello and was having amazing success using the old growth timber due to the resonance that old growth lumber produces when used for musical instruments. This, due to the tight/dense rings of the timber...which is becoming harder and harder to come by.
I grew up in northern Lousiana, and, if memory serves me right, the Red and Sabine rivers were once blocked by trees sometime in the late 1800's (My Louisiana history is a bit hazy...been years since I've been back) and I think Capt. John Smith, of Pocahantas fame, was the one that came through and cleared the river(s) in order to allow trade in that region to continue. But the important point here is that if you are interested in recovering old grow timber, that may be a place to start. Probably still quite a few old growth trees down there. A different kind of treasure, so-to-speak. I'm sure that there are some other researchers or historians here that can offer some more information.
Mike