I installed two boxes like that years ago on a lake we owned. I seldom saw wood ducks, but sometimes they would stop by. Even after several years, I never managed to get them to nest in the boxes. I actually set my boxes out in the water (about three or foot feet deep) on a pole, but they ducks never did seem attracted to them.

Did you get any nesting ducks?

Yes Mike was mowing the grass around the edge of the pond, bent down to pick up a branch that was on the ground in front of one of the nesting boxes, and a wood duck flew out of the hold and scared the @!X% out of him. Got a chuckle out of that. I never actually saw any babies though. I am still working full time and wasn't home during the days to notice. I also need to read up on their habits - I don't know if they actually are in the water a lot like the Canadian geese babies are, or if they are more elusive by staying mostly in the woodline and trees.