I think Tom's right, beavers have a very good whiffer on the front of their face. Air currents travel differently over open water than they do over land, too. If you are talking about "pulling" a beaver over to a location by lure scent, you should consider the air currents and flows also. Visuals are also big in beaver trapping. Beaver seem to be interested in the work of other beavers. A pile of mud on the bank, a slicked up slide trail, a freshly cutoff tree stump near the water...all visuals to a swimming by beaver.
jim-NE