I'm guessing these pictures were taken in August. Jason was in Missouri for the bridge conference and traveled around Iowa, too, before returning to Germany. He's posted a lot of pictures from Iowa recently. I'm not sure if this is the case or not, but it may have automatically inserted "lost" when he chose "replaced by new bridge." I see people say "replaced" a lot when "bypassed" makes more sense. If you mark a bridge as "replaced" on this site, it usually lumps it into the "lost" category.
Satellite view confirms a structure over the waterway. Whether or not it “officially” exists is another matter. In my travels I ran into a case where I photographed a bridge, inquired of it's origin, and was told it did not exist period.
If these are recent pictures, is the bridge really lost or just bypassed?
The bridge has been bypassed by a new bridge. I found this one by chance while looking for another bridge in the vicinity. Judging by its appearance while on the bridge, it appears it has been for abandoned more recently than 1979 (according to NBI)- say the early 1990s. I will try and inquire more about this bridge and should my hunches be correct, changes will be made here.