[Terinalo]

I just finished a round of match play where I won 1 up. On hole #5 my opponent hit his second shot from behind some trees. It was a drawing shot but the problem was that there is a water hazard down there and some narley brush left of the water. We couldn't find the ball, and niether of us saw it go into the water due to the trees. He and I both figured it went in the water so he took a drop from where he assumed his ball entered the hazard. Was this correct? I thought he should have declared his ball lost and went back and hit another one from his original spot.